Cable Machinery dictionary

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10BASE-2    A thin-coaxial-cable  version of an IEEE 802.3 network.
10BASE-5    A thick-coaxial-cable version of an IEEE 802.3 network; very similar to the original
Ethernet specification.
10BASE-F    A fiber-optic version of an IEEE 802.3 network.
10BASE-FB    That portion of 10BASE-F that defines the requirements for a fiber backbone.
10BASE-FL    That portion of 10BASE-F that defines a fiber-optic link between a concentrator and station.
10BASE-FP    That portion of 10BASE-F that defines a passive star coupler.
10BASE-T    A twisted-pair cable version of an IEEE 802.3 network.
4B/5B Encoding.    A signal modulation scheme in which groups of four bits are encoded and transmitted in five bits in order to guarantee that no more than three consecutive zeroes ever occur; used in FDDI.
802.3 network.    A 10-Mbps CSMA/CD bus-based network; commonly called Ethernet.
802.5 network.    A token-passing ring network operating at 4 or 16 Mbps.
8B/10B encoding.    A signal modulation scheme in which either four bits are encoded into a five-bit word or eight bits are encoded in a 10-bit word to ensure that too many consecutive zeroes do not occur; used in ESCON and Fiber Channel.

AAC, All-aluminum conductor

Used for overhead transmission lines, being lighter than ACSR but without the strengthening steel core.

Abrasion Resistance    Ability of material or cable to resist surface wear.
Absorption                          loss of power in an optical fiber, resulting from conversion of optical power into heat and caused principally by impurities, such as transition metals and hydroxyl ions, and also by exposure to nuclear radiation.
Accelerated Aging    A test performed on material or cable meant to duplicate long time environmental conditions in a relatively short space of time.
Accelerated life test    A test in which a cable is subject to extreme conditions to determine the life of that cable. Accelerator    A chemical additive which hastens a chemical reaction under specific conditions. Acceptance angle    The half-angle of the cone within which incident light is totally internally reflected by the
fiber core.  It is equal to arcsin (NA).
Accumulator    A device for maintaining constant tension in a moving wire or for accommodating  the build-up of wire in a continuous line when the final take-up is stopped for reel or spool changing.  It consists basically of two sets of pulleys, the wire being led from the first pulley of one set to the first pulley of the other, then round the second pulley of the first set and so on.  Either one or both sets of pulleys are movable so that when tension from the pull of the take-up is reduced the distance between the sets of pulleys is automatically increased to enable the device to hold a greater length of wire.  In many instances the moving section of the accumulator is arranged to provide a signal proportional to the position of this moving section in order to control the speed of the take-up drive.

ACSR, Aluminum conductor steel reinforced
Activator    A chemical additive used to initiate the chemical reaction in a specified chemical mixture.
Adjacent Conductor    Any conductor next to another conductor either in the same multi-conductor  cable layer or in adjacent layers.
Adjustable dies.    Have movable sections of tungsten carbide which fit together within a frame to form the shaped hole.  The size and shape of the hold can be adjusted by means of screws or by inserting a set of spacers of the appropriate size between the sections and the frame.
Ageing    Also known as age hardening.  A change in properties, generally an increase in hardness, that may occur gradually at atmospheric temperatures (natural ageing, also known as precipitation hardening); and more rapidly at higher temperatures (artificial ageing).  Also changes taking place with time which occur in a depositing solution (generally as a result of electrolysis) which modifies the characteristics of the deposit obtained or which affects


the working conditions of the solution.
Air cooling    One method of reducing the temperature of wire during drawing by directing a jet of air on to the wire capstan.  See entry for wire-drawing temperature.  Cooling of wire in air after patenting is more properly termed air patenting.
Air wipes    Used for removing most of the water from extrusions, insulated wires or cables as they leave a cooling bath.  Air is directed through nozzles or through slits in interlocking wheels between which the material passes.
Albert lay wire rope.    Wire rope in which the wires in the strands and the strands in the rope are laid in the same direction.  Also known as Lang's lay rope.
Alfameter    A German instrument which uses light reflection on die bores for determining the drawing angle and at the same time checks the surface quality of the die.
Alloy    A combination of two or more metals to form a new or different metal.
Alpha brass    Any single-phase brass containing more than about 63 per cent copper.  Characterized by high ductility.
Alternating Current    An electric current that continually reverses its direction giving a definite plus and minus wave form at fixed intervals.

Alternating Current
Resistance

The resistance offered by any circuit to the flow of alternating current.

Aluminizing of steel wire    The coating is usually applied by hot dipping, but pretreatment of the wire to obtain a high degree of surface cleanliness is very important, and after pickling the clean surface must
be maintained up to the moment of immersion in the molten aluminum.  A protective film can be provided by dipping in a hot flux solution - titanium or zirconium fluoride in one process, borax and ammonium chloride in another. Alternatively, the wire can be preheated in a reducing atmosphere and then made to enter the aluminizing bath through a submerged chute in which a reducing atmosphere circulates. The advantages of the first process are simplicity of operation and control, and low capital cost. On the other hand, a much higher line speed can be used with the second process since the aluminizing bath does not have to heat the wire to a temperature at which the iron-aluminum reaction can begin; also, with suitable preheating, line speed is not dependent on the gauge of wire
processed. The wires are guided into the aluminizing bath under a refractory sinking roller and emerge vertically from the molten aluminum surface to be wiped and cooled prior to coiling.
The coating consists of an extremely brittle iron-aluminum alloy adjacent to the steel and outer coating similar to the aluminum in the bath.  The proportion of the coating composed of the intermetallic compound must be restricted by incorporating silicon in the aluminizing bath if a ductile coating is required.  Aluminizing is carried out at temperatures of about 700 degrees C and coating and heat treatment to provide a suitable structure for re-drawing can therefore be carried out together.
Power costs for the higher temperature necessary are about twice as high as for galvanizing.  The whole process also demands closer control, which in itself increases costs.  Material costs on the other hand are very little different since the principal item is the aluminum which is cheaper than zinc per unit volume. Routine maintenance of aluminum baths is required to reduce iron content, aqueous flux carry-over and suspended aluminum oxide. See also entry for Alumoweld wire.

Aluminum and aluminum alloy wire.

Drawing procedures vary according to the widely different properties required of the end product.  Reductions in area per die average 20 to 25 per cent on continuous machines or up to 40 per cent when single-holding pure aluminum.  Tungsten carbide dies are generally used down to 0.7 mm (0.028 in) and diamond dies for smaller diameters.  Die angles vary from 14 to 18 degrees. Lubricants are usually fairly high viscosity mineral oils with a
small percentage of additives for heavier drawing, lower viscosity oils for smaller diameters and soluble oils for fine wires. Both dies and drawing blocks are commonly water-cooled and lubricant is recirculated and cooled because increased wire temperatures can result in softening. Rectangles with width/thickness  ratios of 4:1 can be produced


conventionally,  frequently on continuous machines. Drawn from wire rod produced by hot rolling (see entry for copper wire rods), by casting and also by extrusion.
Alloys of aluminum are scheduled in the B.S. 1470-1475 for the wrought forms and
B.S. 1490 for castings. B.S. 1475 specifies the materials used in wire form, which are:
99.8% and 99.5 purity aluminum metals G1A, G1B - used for general purpose wire, welding wire and wire for metal spraying.
Al-Mg alloys (materials NG4, NG5, NG6) and Al-Mg-Mn (material NG61) - for welding wire, nails and other fixings, etc, medium strength fencing.
Al-Mg-Si and Al-Mg-Si-Cu alloys (materials HG9 and HG20) - moderate strength heat-treated alloys for nails and other fixings, knitting needles, etc.
Al-Cu-Mg-Si alloy (materials HG15) - strong heat-treated alloy for general purpose
wire.
Al-Si alloys (materials NG2, NG21) - for welding and brazing wire.
B.S. 1473 specifies the materials used for stock for rivets (R) and for bolt and screw stock (B). Rivet stock is available in materials R1B, NR5, NR6, HR15 and HR30 and bolt and screw stock in NB6, HB15, HB20 and HB30.  There are other special wire alloys
also, including the L series of British Standard materials for aircraft requirements and the
DTD specifications issued by the DTI.
A separate series of wire materials used for overhead electrical conductors and
insulated cables is supplied to a guaranteed minimum electrical conductivity - usually 61% IACS (Cu=100). These are scheduled in B.S. 215 - Aluminum and steel cored aluminum conductors for overhead power transmission purposes. By careful control of impurities, average values as high as 62.5 % IACS for hard drawn wire are not uncommon.  Pure aluminum, Al-Mg-Si alloys and Al  0.7 % Mg alloy are available, the aluminum alloy commonly used for electrical wire contains 0.5 % each of magnesium and silicon, which, by careful control of manganese, titanium and vanadium contents gives a minimum conductivity of 53% IACS.
Pure aluminum wire for electrical conductors GIE is specified in B.S. 2627, reference to this being given in B.S. 215.
Aluminum cables.    Aluminum conductors are used extensively in insulated cables, the basic standard for which is B.S. 6791.  This gives requirements for solid and stranded conductors of both circular and shaped section in insulated cables; it is concerned only with the conductor in the finished cable - requirements for the wire or solid conductors used in manufacturing the cable are given in B.S. 2627 and B.S. 3988.
Solid sector power cables utilize three solid sector aluminum conductors and aluminum armour. The armour in this case acts as neutral and earth return and obviates the fourth conductor often incorporated with the phase conductors. Each of the phase conductors in this case is of fully annealed aluminum of 99.5% purity having a conductivity of approximately 63% IACS.  The armour material is of similar purity to the conductors but
is in the H condition.  The armour takes the form of flattened wire with the individual wires laid edge to edge round the cores. Each phase conductor is P.V.S. insulated and is a
120 degree segment. In this way the cable diameter is reduced to a minimum, thus reducing the size and subsequent cost of insulation and armouring material. The single- phase version of this cable is also manufactured, comprising a single P.V.C. insulated conductor over which aluminum armour is applied: this is then further P.V.C. insulated.
Aluminum as an armouring material utilizes both 99.5% aluminum and aluminum- magnesium alloy wires. The use of non-magnetic armouring is essential in single-core cables working in AC conditions due to hysteresis losses introduced in magnetic armour wires.
Stranded aluminum conductors can be used instead of rigid bus-bars for handling
currents in the 7000A DC range. This system obviates the need for flexible links. Main advantages are lower installation costs and improved strength and flexibility.
Alumoweld wire.    Steel wire with a substantial coating of aluminum, the coating constituting 25% of the


cross-sectional  area of the wire. It is used as a simple composite conductor for electrical transmission lines where high strength needs to be combined with reasonable conductivity. The wire drawn from Alumoweld rod which is produced by passing cleaned steel rod through a powder applicator at the exit of which the aluminum powder is compacted on
the rod by rolls.  The clad rod is then heated and further compacted before drawing down.
AM    Amplitude modulation.
Ambient Temperature    Any all encompassing temperature within a given area.
American Wire Gage    A standard used in the determination of the physical size of a conductor determined by its circular mil area.  Usually expressed as AWG.
Ampere    The unit used for measuring the quantity of an electric current flow.  One ampere represents a flow of one coulomb per second.
Amplitude modulation    A transmission technique in which the amplitude of the carrier is varied in accordance with the signal.
Angular misalignment    The loss of optical power caused by deviation from optimum alignment of  fiber to fiber or fiber to waveguide.
Anneal    To subject to high heat with subsequent cooling.  When annealing copper; the act of softening the metal by means of heat to render it less brittle.
Annealers/Annealing            Heating to, and holding at a suitable temperature, followed by a cooling at a suitable rate, for such purposes as inducing softness, improving machinability improving cold working properties obtaining a desired structure and removing stresses.
Black annealing. Annealing where no special precautions are taken to ensure the product being free from scale or discoloration.
Bright annealing.  Annealing in a protective medium, usually with reducing gages, to prevent discoloration of the bright surface.
Continuous strand annealing. Annealing by means of a machine which can be placed between the final capstan of a drawing machine and the spooler, so that wire is drawn, annealed and spooled in one operation.  Also known as continuous resistance annealing, this process has been used for copper wire for many years, but there is increasing interest in its use for aluminum.  See entries for annealing of copper wire and annealing of aluminum wire.
Cyclic annealing.  A process consisting of heating metal to a temperature above the upper limits of the critical temperature range followed by transfer to a salt bath quench furnace, which is maintained at a suitable temperature below the lower limits of the critical temperature range.
Flame strand annealing.  Annealing by passing the wire continuously through a line of gas flame jets controlled with great accuracy.
Full annealing.  Heating iron base alloys above the critical temperature range, holding above for a period, followed by slow cooling.
High speed annealing.  A process for high speed continuous heat treatment has been developed by BISRA to give improved tensile strength and elongation.  Throughput speeds of several hundred feet per minute should be possible.
Isothermal annealing.  Heating to and holding at some temperature above the transformation range, then cooling to and holding at a suitable temperature until the austenite to pearlite transformation is complete, and finally cooling freely.
Loop processing.  Wire or rod coiled into overlapping loops on a conveyor which runs through the furnace make it possible to use a much shorter furnace than in strand processing.
Open annealing.  Another name for black annealing.
Process annealing.  Heating, usually to a temperature below the transformation range, to remove the effects of cold work and permit further cold work.
Resistance annealing.  See reference to Continuous Strand Annealing.  Annealing of
Copper Wire.
Salt annealing.  Annealing wire by immersion in a molten salt mixture at a temperature


of up to 700 deg. C.  With this method, annealing is uniform and no scaling occurs because when the coils are taken out of the salt bath, the adhering salt film protects the material from contact with oxygen.  Though operating costs are high, the process is fast and therefore only a relatively small plant is needed.
Strand annealing.  Passing of wire in single strand form through a furnace.
Sub-critical annealing.  Heating to and holding at some temperature below the transformation range, followed by cooling at a suitable rate.  After drawing, wire is given a sub-critical anneal in either a furnace or a salt bath, which conditions the material so that it can receive further drawing.
Vacuum bright annealing.  Annealing in a container in which a very high artificial vacuum is created, reducing the oxygen in the annealing pot to such a degree that scaling or coloring of the material is impossible.


Annealing of aluminum wire

Annealing temperatures for aluminum and its alloys range from 350 to 450 deg. C., depending on the quality, in certain cases, with pure aluminum and some aluminum alloys, it is possible to partially anneal fully hard-drawn material to achieve intermediate tempers. This also enhances ductility in comparison with wire whose final temper has been
achieved solely by drawing.  Continuous strand annealing (see entry for annealing of copper wire) appears to offer considerable advantages since to obtain tensile strength required for cable specifications by conventional methods the wire has first to be fully annealed and then redrawn through the correct number of dies.
The addition of a cleaning wheel and tank mounted between drawing machine capstan
and annealer is essential for aluminum.  Oxidation of a very high resistance occurs on aluminum at a very low temperature and the pre-heat legs of aluminum annealers need to be considerably longer to reduce temperature to approximately 100 degree C.  The pre- heat leg, as well as the annealing leg, should be fully protected from the general atmosphere.

Annealing of copper wire.    Annealing in non-oxidizing atmosphere is suitable for copper wire in coils or on bobbins.
The wire becomes perfectly bright and is ready for use without further pickling or
cleaning.  Well refined and rolled copper can be drawn to fine limits throughout in its hard drawn state.  For instance, best quality copper may be drawn direct from rod on to reels holding 230 kg. to 450 kg. and then redrawn to smaller gauges without intermediate annealing.
Copper has a comparatively low annealing temperature, usually between 200 deg. and
400 deg. C., depending on many factors, and it oxidizes rapidly.  Therefore, although the metal can be annealed at low temperatures, it must be protected against oxidation during industrial annealing operations, unless it is desired to grow an oxide scale in order to remove surface defects, a practice which is sometimes adopted in early process anneals.
In addition, in final annealing operations the presence of sulphurous atmospheres must be
avoided or sulphide tarnishing will occur.  Wit the tough-pitch varieties of copper, the gassing reaction which occurs between cuprous oxide and hydrogen becomes serious at temperatures much above 400 deg. C.
As copper can be pressure-welding  with the application of only slight amounts of pressure at high temperatures in clean atmospheres (possibly slightly reducing atmospheres are necessary), a pronounced tendency to "stickiness" occurs in adjacent
turns of wire.  Stickiness can be avoided by using the continuous strand annealing process.
Vacuum bright annealing is also increasingly used, but cooling after annealing must take place in the complete absence of air to avoid oxidative discoloration.   Heat loss from the copper charge in an evacuated annealing chamber is relatively slow but cooling times can be greatly reduced if carbon dioxide is admitted to the annealing vessel during cooling since heat loss takes place by convection and conduction in addition to the original radiation.
In continuous strand annealing or resistance annealing, a machine is placed between the
























Annealing of stainless wires.

final capstan of a drawing machine and the spooler, so that wire is drawn, annealed and spooled in one operation.  Annealing temperature is reached by current fed through the wire from a sheave and the wire is annealed in a neutral atmosphere.  If the wire being processed is increased in area, then for a given voltage, the current passed will increase in sympathy, since the resistance decreases as the area increases.  The net result is that the
power supplied automatically adjusts itself to the size of wire being processed, without any necessity for changing the voltage.  Prevention of the oxidation of the heated wire is achieved by enclosing the wire in a steam atmosphere in the final heating zone, after which it is taken through a cooling water tank and away to the spooler through a cooling tube down which a continuous flow of water is maintained.  Experiments have shown that fully softened wire, free from any trace of springiness, suitable for enameling for winding electrical coils, can be obtained by the continuous strand annealing process, using higher temperatures than usually employed on these machines and with a better protective atmosphere than the normal steam atmosphere.  Care has to be taken to avoid damage to
the wire surface through sparking between the pulleys and the wire.
Annealing of copper alloys.  Excessive grain growth must be avoided during annealing of brass and minimum temperatures consistent with sufficient softening should be adopted. About 500 to 600 deg. C. is usually satisfactory for normal compositions of brass and phosphor bronze wire, with higher temperatures for silicon bronze and nickel silvers - 750 deg. C. or above for some high nickel alloys.  Furnace gases will cause discoloring if they contact the copper alloys, and nonoxidizing furnace atmospheres are often preferred. Usually carried out in a protective atmosphere.  When annealing through a continuous strand-type furnace, a rough guide to wire speed is that it should pass through the heating zone at the rate of one second for each 0.025 mm. of wire diameter.  Annealing of austenitic stainless steels is carried out by heating to 1,050 deg. C., followed by a quick cool, either in air or water.  Annealing temperatures for martensitic stainless steel vary according to quality, but usually the best temperature is around 750 deg. C., and the wire should then be air cooled.

Annular Conductor -    An annular conductor consists of a number of wires stranded in reversed concentric layers around a saturated hemp core.

Anode.    The positive electrode of the electrolytic cell at which negative ions are discharged, positive ions are formed, or other oxidizing reactions occur.  In anodic brightening a lustrous surface is imparted to a metal by making it an anode under suitable conditions; also known as electrobrightening.  In anodic etching the surface layer is removed from a metal by making it the anode in a suitable electrolyte at a suitable current density.
Anodizing    The production of a highly protective and tenacious form of oxide as a coating on aluminum, and also on certain other light alloys.  The anodizing process increases the thickness of the oxide film normally present on aluminum and is carried out by making the metal the anode in a suitable electrolyte such as chromic acid or sulphuric acid.  The latter gives a colorless film which has a mordant action for certain dyes, so that attractive
colored finishes can be obtained by immersing the anodized aluminum in a boiling solution of a suitable dyestuff.  To obtain the maximum protective value whether the film is dyed or not, it must be sealed by treatment in boiling water or dilute chemical solutions such as nickel acetate.

ANSI, American National
Standards Institute

A federation of trade, technical and professional organizations,  government agencies and consumer groups.  Coordinates standards development and publishes standards.  Operates a voluntary certification program.

Anti-Oxidant    A substance which prevents or slow down oxygen decomposition of a material.
Anti-Ozonant    A substance which slows down material degradation due to ozone reaction.
APD    Avalanche photodiode.
Area reduction.    The area reduction made during wire drawing can be calculated from the elongation as follows: A.R% = 100 x E% divided by 100 + E%.  An elongation of 11.1 per cent


therefore represents an area reduction of 10 per cent.
Armature binding wire.    (1) A phosphor bronze wire produced in various sizes from 2.5 to 5 mm.  previously tinned but this now discontinued.  See B.S. 384.  (2) A tinned high tensile patented steel wire produced in sizes from 0,4 to 3.2 mm with tensile strength of 190 to 210 kg/mm. squared Finally hot-dip tin coated after drawing.
Armature winding.    A winding in which both coil sides are on the outside of the core or drum, but at different points on the drum depending on the pole pitch desired.  As an example a two-pole armature would have two sides of a coil spaced approximately 180 deg. apart, a four-pole armature 90 deg. apart.
Armature wire.                       Stranded annealed copper wire, straight lay, covered with soft loose white cotton braid.  It is used for low voltage, high current rotor windings in motors and generators.  Straight lay permits the forming in armature slots and in compressibility.
Armature.    That part of a machine, whether rotating or stationary, which carries the winding and in which the principal e.m.f. is induced.  This term is usually limited to the rotating part of a D.C. machine.
Armor    Mechanical protection usually accomplished by a metallic layer of tape, braid or served wires.  Normally found only over the outer sheath.
Armor -    The outer most layer of a cable applied for mechanical protection usually consisting of a layer or layers of a metallic tape, braid, or served wires.

Armouring wire.    In brass or aluminum for electric cables, high tensile galvanized steel for submarine cables and galvanized mild steel for ordinary cables and rubber tubing.  Galvanized high tensile steel wire of 96 to 144 kg./mm. squared. tensile is manufactured for armouring submarine cables in sizes ranging from 2 to 3.5 mm. dia. B.S. 1441 and B.S. 1442 specify armouring wires for submarine and other cables.
Armouring.    Wire or metal tape is often applied over a bedding of hessian or jute to protect cables against mechanical damage.  Magnetic materials are usually applied only to cables containing two or more cores.  Single-core cables are often left unarmoured.  The presence of steel within their magnetic field causes marked heating losses, while the alternative of
tin bronze or silicon bronze wire or tape armouring can also result in appreciable losses, which are only minimized if armouring of higher conductivity is used.
Arrowstraight Cable -    A bare conductor which has been semicompressed  by approximately 3%. (SW)
Asbestos wipers.    Used in hot-dip galvanizing when it is desired to cover the wire with a thin coat of zinc.
This is known as tight wiping.  The wires pass from the galvanizing bath through the wipers placed immediately next to the exit end of the bath.
ASC -    Aluminum Stranded Conductors.
Aspect ratio.    Ratio of width to thickness of a shaped wire. A low aspect ratio indicates a section with a thickness approaching that of the width.

ASTM, American Society for Testing Materials.

An organization that tests materials and attempts to set standards on various materials for industry.

Attenuation    a general term indicating a decrease in power from one point to another.  In optical fibers, it is measured in decibels per kilometer at a specified wavelength.
Attenuation    Power loss in an electrical and communication  system.  In cables the loss is expressed in decibels per unit length of cable.
Attenuation -    The measure of the loss of energy between the transmitting and receiving terminal and depends on several external and internal factors.
Attenuation, Voltage    Either (1) a decrease in signal voltage may transmission from one point to another, or the process thereof, or (2) transducer, the scalar ratio of the signal input voltage to the signal of voltage.  This ratio is sometimes expressed in decibels by multiplying common logarithm by 20.

Attenuation-limited operation .

The condition in a fiber-optic link when operation is limited by the power of the received signal (rather than by bandwidth or by distortion.)

Audio Frequency    Pertaining to that band of frequency which is audible to the human ear.  Usually 20-20,000




Autocatalytic
Degradation

cycles per second.
Pertaining to degradation of certain material whereby the breakdown products of the initial phase of their degradation accelerate the rate at which subsequent degradation proceeds.

AVA -    Asbestos and varnished Cambric insulated, 110 degrees C dry location.

Avalanche photodiode.       A photodiode that exhibits internal amplification of photocurrent through avalanche multiplication of carriers in the junction region.
AVB -    Asbestos and varnished Cambric insulated, 90 degrees C dry location.

AVL -    Asbestos and varnished Cambric uninsulated, 110 degrees C dry location, lead sheathed.
AW -    Abbreviation for Alumoweld.
AWAC -    A cable consisting of a composite of aluminum strands and aluminum clad strands.
Copperweld Enterprises.

AWG, American wire gauge

The system most commonly used in the United States for describing the size of copper wire, it is based on the circular mil system, 1 Mil equals 001 in.

AZ -    A thin coating of some metal part (usually steel or iron) with aluminum by electroplating.
Backscattering.    The return of a portion of scattered light to the input end of a fiber; the scattering of light in the direction opposite to its original propagation.
Ballooning                                Faulty or erratic paying-out of yarns or wires from the spool carriers of a braiding machine causing loose snaking yarns or wires.  Caused by worn or damaged ratchet, pawl or spring on the carrier, a loosely fitted supply spool, or because the machine is running too fast.

Bandwidth-limited operation.

The condition in a fiber-optic link when band-width, rather than received optical power, limits performance.  This condition is reached when the signal becomes distorted, principally by dispersion, beyond specified limits.

Bandwidth.    A range of frequencies.
Baseband.    A method of communication  in which a signal is transmitted at its original frequency without being impressed on a carrier.
Baud.    A unit of signaling speed equal to the number of signal symbols per second, which may or may not be equal to the data rate in bits per second.
Beamsplitter.    An optical device, such as a partially reflecting mirror, that splits a beam of light into two or more beams and that can be used in fiber optics for directional couplers.
Bedding.    Of an armored cable.  A layer or layers of fibrous material, which may be permeated with water proof compound applied to the cable beneath the armoring.  A layer or layers of waterproof compound may also be present.
Bend loss.    A form of increased attenuation in a fiber that results from bending a fiber around a restrictive curvature (a macrobend) or from minute distortions in the fiber (microbends).
Bend test.    This test of ductility is usually carried out on a hand machine consisting of a bending lever (carrying the specimen locator) pivoted on a frame which incorporates a vice having recesses in the jaws to carry the dies over which the wire test piece is bent.  The wire test piece is held at one end by the vice and bent at right angles over one of the jaws which is formed to a special radius.  It is then bent in the reverse direction through 180 degrees
over the other jaw formed to the same radius, these actions being repeated to see how many complete 180 degree bends are made before fracture.  Also known as the reverse bend test, and mainly on the Continent, as the flexion test.
BER    bit-error rate.
Beryllium.    Added to copper to increase hardness and strength, the percentage of beryllium in the alloy being usually 1.7 to 1.9 per cent.
Copper cobalt beryllium is a high conductivity copper alloy containing about 0.4 per cent beryllium and 2.6 per cent cobalt.
Copper beryllium is a copper alloy containing 1.7 to 1.9 per cent beryllium and small amounts of nickel or cobalt, having great hardness; used for springs, it is usually supplied after being solution heat treated and subsequently cold drawn to a tensile strength of at least 790 N/mm square. Precipitation heat treatment carried out after forming raises the


tensile strength of this alloy to a minimum of 1300 N/mm square.
Biflaker.    A high-speed de-reeling device consisting of a precision engineered metal disc holding a metal ring designed to fit in the lip of the disc.  The disc rests on the top of the LTV (long traverse vertical) reel and the wire is paid off between the lip of the disc and the metal ring.

Billet.    A semi-finished rolled product intended for re-rolling or forging, usually square with chamfered or radiused corners and with a cross-sectional  area generally not more than 160 cm. square. A billet for production of wire rod is usually 50 to 120 mm. square and about
9 to 19 m. long, to produce coils weighing up to 1,400 kg.
Binder    Usually a spirally served tape or thread used for holding assembled cable components in place awaiting further manufacturing operations.
Binder -    A spirally served tape or thread used for holding assembled cable components in place. BINDERS (Need def)
BIT    Abbreviation for binary digit. A unit of information equal to one binary decision or the designation of one of two possible and equally likely states (such as O or 1) of anything used to store or convey information.
Bit-error rate    the ratio of incorrectly transmitted bits to correctly transmitted bits.
Bit.    A binary digit, the smallest element of information in binary system.  A 1 or 0 of binary data.
Black annealed wire.    Wire annealed without protective atmosphere; it has a scale surface finish: See
"Annealing".
Blistering.    A defect on or near the surface of formed metal caused by gas bubbles which failed to escape from the original molten metal.  Can also be caused by overheating, or moisture in furnace atmosphere.
Block.    A power driven tapered capstan mounted on a vertical or horizontal shaft.  It pulls the wire through the die and serves also to collect the wire in coils, the final block of a multi-die machine being equipped with devices for easily stripping the coil.  Blocks may be water or air cooled and are usually in the form of a casting of complex design to permit internal cooling. 1 1/2 percent nickel cast iron is often used while blocks with hardened inserts are used for carbon and alloy steels, mainly for single hole machines.  Block life can be considerably increased - a factor of seven is claimed - by means of a coating of chrome oxide which can be applied again and again to extend the life of the block indefinitely.
Blueing.    Either (1) a blue oxide film produced on steel by low temperature heating, or (2) heat treatment of steel springs to relieve strains caused by cold work, or (3) baking in a drying oven until the bright cleaned wire turns blue under the lime coat. Blueing, produced by heating to temperatures around 300 deg. C. (572 deg. F.), whilst not providing any corrosion protection, is often used as the finish for heat-treated springs.  To obtain a good blued finish it is necessary to have a high degree of polish and this is usually obtained by barrel-polishing  in sawdust.  The blueing is usually carried out in forced air circulation or rotating barrel type furnaces, the parts being heated for only a few minutes.
Blueing of small components may be carried out in several ways.  The simplest method is a dry treatment in air and can generally only be applied to components which have a fairly good polished surface to start with.  A second method is oil blueing which consists
of heating the parts to a temperature of about 200-300 deg. C., quenching them in a good
quality quenching oil (usually whale oil) and then reheating the parts to about the same temperature in order to burn the oil on the surface.  A third method is to pass either steam or partially burnt gas over the charge at temperature.  When using a steam atmosphere the temperature of the furnace is normally held at 550 deg. C.  The operation comprises essentially of charging the load into a furnace held at the operating temperature and admitting atmosphere.  After the components have been held at temperature for about 1/4 hour or so, the load is then discharged and no further treatment is required.  The temperature and choice of atmosphere depends entirely upon the hardness required on the


component after heat treatment.
Bobbins -    Metal spools used for taking up drawn wire and subsequently used for payout packages in cabling and stranding equipment.
Braid    A fibrous or metallic group of filaments interwoven in cylindrical form to form a covering over one or more wires.
Braid -    A fiberous or metallic group of filaments interwoven in cylindrical form to form a covering over one or more wires.
Braid Angle    A term used in the determination of the braid configuration relating to the angle of the braided filaments or fibres in relationship to the axis of the cable core being braided.
Braid Carrier    A spool or bobbin on a braiding machine holding one group of strands or filaments consisting of a specified number of ends.  The carrier revolves during the braiding operations.
Braid Ends    In a braid the given number of strands used to make up one carrier.  The strands are wound side by side on the carrier bobbin and lay parallel in the finished braid.
Braid.    A woven protective outer covering over a conductor or cable.  It can be made of materials such as cotton, glass, nylon and asbestos fibers.  Usually the braid is saturated with an impregnant to protect it against moisture and fraying.
Formed by laying-up a number of strands of material diagonally in such a way that one or more strands pass alternately over and under one or more strands laid up in the opposite direction.  Divided into three general classes.
Flat braids in the form of a flat strip or tape, normally in widths of from 3.2 to 50 mm.
Round braids which are laid up to form a tube, a solid cord, or are wrapped round a center core.
Fancy braids, which are purely ornamental and include fancy elastic or lace, in a regular braid, two strands pass alternately over  and under two strands laid up in the opposite direction and the finished braid shows two complete double ribs of herring bone formation in each line.  Flat braids are known to the trade by the number of lines in the completed braid.
Plain flat braids are normally made with an uneven number of strands and the total number of strands in a completed braid can be determined from the number of lines without the necessity of counting the individual ends of yarn or wire.  The total number of strands in a normal flat braid is equal to four times the number of lines plus one.  Tubular braids are usually made with an even number of strands and the total strands equal four times the number of lines.
There are several styles of braid stitch in general use - Symmetric: Diamond or Basket -
1:1, Standard or Regular - 2:2 and Hercules - 3:3.  The figures indicate one over and one under or two over and two under as the case may be.  Sometimes, however, it is desirable to use asymmetric stitching such as 1:2 or 1:3, the figures indicating one over and under two or one over and under three.
A diamond or basket weave can be produced on a standard tubular braider simply by
omitting every other carrier or alternatively by re-arranging the carriers to run in pairs - two hornslots loaded and two empty, making sure that each pair will clear the pair running in the opposite direction.  A ribbed effect can be produced with either flat or tubular braids by using warp threads and to do this it is necessary to equip the machines with hollow horngear studs and warp guides.  By running some of the spool carriers empty, open work braids can be produced and a variety of effects are possible by using contrasting colors or inserting different types of warp threads.  Rich-Rack braid is produced by increasing or decreasing carrier tensions in uniform steps throughout each half of the total carrier formation.
Braided wire.    Woven bare or tinted copper wire used as shielding for wires and cables and as earth wires for batteries or heavy industrial equipment.  There are many different types of
construction.
Braider    A machine used to apply a woven fibrous or metallic braid over a cable diameter.


Braider -    a machine used to apply a woven fiberous or metallic braid over a cable.
Braiding.    (1) Plaiting wires or yarns diagonally to form tubes, solid cords or flat ribbons. Tubular braids are made on machines with 8, 12, 16, 24 or 48 carriers. Flat braids are produced on machines with 9, 13, 17, 21, or 49 carriers.  Machines are in existence with larger numbers of carriers but these are generally considered as special purpose braiders. (2) Plaiting cotton or yarn over an electrical conductor, or wire for screening purposes similar to TV cable.
Brake Wire    Wire used in mobile-home, travel and truck trailers to supply current to the electrical
braking system.
Brake Wire -    Wires used in the manufacture of both home and truck trailers to supply current to the electrical brake system.
Brass coating.    Wire has to be brass coated by electrolytic deposition after etching, whereas copper coating can also be produced on wire after etching by simply dipping into a solution of copper sulphate without the passage of electricity.  The etching of the wire removes all traces of drawing lubricant to provide an absolutely clean surface; this is essential to achieve complete adhesion of the bras deposit.  With the electrolytic process, anodic etching in line with the coating baths is the most satisfactory means of cleaning the wire surface. With this method the wire is the anode and it is passed through an electrolyte at a suitable current density before entering the coating bath.  The electrolytic process gives an even coat which can be controlled to give a depth that will meet most coating requirements.  70:30 electrolytic brass coatings are excellent for rubber bonding applications and hence are widely used on tyre bead wires and hose reinforcement wires.
Two other reasons for brassing rather than coppering are - brassed wire is often considered to be more attractive, especially when gilded, and gilding on brassed wire is general practice; also electro-brassed  wire has more corrosion resistance than chemically coppered wire for most ordinary exposure conditions.
Another method is to coat the wire electrolytically first with copper and then with zinc, followed by heating the wire to 420 to 550 deg. C., which results in fusion of the two coatings to form brass; a number of advantages in regard to uniformity and quality of coating are claimed, while it is stated that more stable conditions are created for drawing the wire.  Excellent adhesion is said to be possible between this brassed wire and rubber.
An appearance approximating to brass can be produced from coppering baths containing tin salts, such coatings being known as bronze or straw lacquers.  Such coatings are often preferred to straight copper coatings for rubber bonding, although they are generally considered inferior to true brass.  As tin salts hydrolyse in acid solution, control of the solution is more critical than with simple copper baths.
Brass wire.    Contains 60 to 90 per cent copper and the balance zinc.  Tensile strength ranges from about 315 N/mm square (annealed) to 685 N/mm. square or more (hard drawn). Most brass wires have a composition of 62-65 per cent copper, with lead usually restricted to well below 0.3 per cent (though it is sometimes desired in amounts up to 2.5 per cent to improve machining characteristics);  within this category fall pin wire, screw wire, nipple wire, riveting wire, etc.  Alloys of higher copper content such as 70:30 brass possess greater ductility and better corrosion resistance, and are used for large-headed rivets, woven wire, etc.; this alloy has a tensile strength of 315 to 630 N/mm square, and sometimes contains a small amount of phosphorus to inhibit dezincification under corrosive conditions.
Other alloys such as 80:20, 85:15, and 90:10 brasses or gilding metals are used because of their color or the fact that they can be brazed with less risk of melting because of their higher melting points.
Brass.    The general name of any alloy consisting essentially of copper and zinc.
Brazing.    The jointing of metals by means of alloys which melt at temperatures well below the melting points of the metals being joined, when these and the brazing material are heated. Brazing wire is manufactured to special requirements as to chemical composition and


surface cleanliness for use in joining metals by brazing.  Brass brazing solder wire generally consists of 60 per cent copper and 40 per cent zinc, but solders of lower melting point - 54 per cent copper, 46 per cent zinc and the 50/50 alloy are also used.  Can be produced as rough slittings from rolled strip, as exact finish is not required.
Breakout    A term used to define a wire or group of wires in a multi-conductor  configuration which
terminate somewhere other than at the end of the configuration.
Bridge cable.    The wire ropes or strands used as the catenary and suspenders upon a suspension bridge.
Examples of a typical suspension cable are given under the entry for suspension cables.
Bright annealed wire.    Wire annealed in a protective atmosphere to prevent oxidation of the surface.  Also known as white annealed wires.

Bright finish after dry drawing.

Can be accomplished by arranging a wet drawing hole at the last die, using a proprietary wet drawing compound which is mixed in a fairly heavy concentration of 15 per cent in water, the last die being flooded with a jet playing into the entrance of the die.  It is, of course, necessary that a the dry soap coat is not removed before it comes to this die as the lubrication is by the compound and the soap coat which is on the wire, but in the course of passing through the last die and the lubricant, this soap coat is removed and the result is a highly polished bright wire.  It is only necessary for a small tank to be incorporated with this last hole: a capacity of not more than 5 to 6 gallons is suitable as the soap and lime on the wire contaminate the material which limits its life to about a week.

Bright rope.    Steel rope formed from wire that has not been coated.
Bright wet drawn.                  Broadly accepted to mean hard drawn wire with surface free of copper coating.  Originally used only for bright wire in which no discoloration was permitted and which had therefore only been subjected to a small degree of wet drawing.  Bright wire is now also produced
by coating with zinc phosphate when it can be drawn through soluble oil as much as 94 per cent reduction in area.  Hence this is also sometimes termed bright wet drawn although its grey appearance is not suitable for the class of wire in which no discoloration is permitted, but satisfactory for other types of bright wire.  It has been suggested that the term "bright wet drawn" should be reserved for the special finish, and that the zinc phosphate finish should be designed "wet drawn" as opposed to "coppered wet drawn."
Bright wire.    Steel wire which has been dry drawn and not subjected to any subsequent treatment. Brinell hardness test.    By forcing a hard steel ball by means of a known standard load or pressure, into the specially polished surface of the material under test, for a standard length of time, an
impression or indentation is made in the material.  This is measured and the hardness of the material is expressed as a number - the Brinell Hardness (B.H.N.), being the ratio between the force applied in kilograms and the resulting spherical area of indentation in square millimeters.  Methods and tables for the Brinell Hardness Test are given in B.S.
240.
British Standards.    A list of the standards dealing with alloy compositions, wire, wire products, cables, and all matters of interest to the wire industry. Copies of British Standards can be obtained from the British Standards Institution, Newton House, 101-113 Pentonville Road, London N1
9ND, and regional offices.
Broadband.    A method of communication  in which the signal is transmitted by being impressed on a higher-frequency  carrier.
Bronze wire.    This term is applied commercially to a copper-zinc alloy (i.e. brass) wire for "bronze"
welding; to copper-cadmium  and to copper-cadmium-tin alloys containing over 98 per
cent copper, for high electrical conductivity coupled with high strength in comparison with pure copper; to copper-silicon alloys containing over 96 per cent copper, used for
electrical resistivity, corrosion resistance, strength or as a welding wire for the inert gas shielded process; and to copper-aluminum  alloys (aluminum bronzes) containing over 92 per cent copper, used for corrosion resistance, high strength or color; as well as being applied, more correctly, to the copper-tin alloys (bronzes, phosphor bronzes or tin bronzes).
The copper-tin alloys containing less than 2 per cent tin are used where a combination


of high strength and high electrical conductivity is required, though they have to some extent been replaced in recent years by the copper-cadmium  alloys referred to above, which can often offer greater conductivity for similar strength.  These low tin bronzes can be drawn on modern high speed machines as used for producing copper and brass wires, though maximum speeds may be limited to half that achieved for copper and die wear is notably greater than for copper or brass.
The higher tin alloys are used for their excellent corrosion resistance and for springs of many types, tin contents as high as 10 per cent being adopted for special springs, though 8 per cent tin is commoner.  The corrosion resistance does not increase much above 5 per cent tin, and it is not usual to use material containing more than 8 per cent tin where this is the main service requirement (e.g., in Fourdrinier wire for the paper-making industry), cost increasing with tin content.  As the tin content increases also, the degree of reduction possible between production anneals falls rapidly, die wear increases and much lower drawing speeds must be used.
Bronze.    The word was originally confined to alloys of copper and tin, but modern usage has extended it in other high-quality copper-rich materials.
Brown and Sharpe gauge.    Also known as American Wire Gauge, is universally recognized in the United States for copper and other non-ferrous wires, steel wire sizes being stated in Steel Wire Gauge (or Washburn & Moen). A new series based on the preferred number series is also being introduced in the U.S.A., intended to replace all gauges in common use.
Buckling.    The deflection of a compression spring from its normal straight form, which is liable to occur when the spring is too long in relation to its diameter.
Buffer coating.    A protective layer, such as an acrylic polymer, applied over the fiber cladding for protective purposes.
Buffer tube.    A hard plastic tube, having an inside diameter several times that of a fiber that holds one or more fibers.
Buffer.    A protective layer over the fiber, such as a coating, an inner jacket, or a hard tube.
Building Wire    Wire used for light and power in permanent installations utilizing 600 volts or less.
Usually in an enclosure and which will not be exposed to outdoor environments.
Building Wire -    Commercial wires used in the building trades.
Bull block.    A wire drawing machine of very heavy construction capable of drawing all sizes of rods between 40 mm. and 9 mm. dia. Usually provided with a single die box, but sometimes provided with an additional capstan to produce a double draft
Bunch Strand    Any number of conductor strands twisted together in one direction with the same lay
length.
Bunch strand.    A conductor in which all individual wires are twisted in the same direction without regard for geometrical arrangement.
Bunch.    A number of wires twisted together in the same direction and in a uniform manner provide a more flexible conductor than a strand.  Flexibility can be further increased by using smaller wires. A number of bunches twisted together in the same direction, and in a uniform manner are known as a compound bunch.
When a number of bunches are twisted together so that each bunch, with the exception of the center one, has a helical form of predetermined  lay ratio, this is known as a stranded bunch. When the number of bunches exceeds four they are arranged in concentric layers. alternate layers are usually laid in opposite directions.
A number of stranded bunches twisted together so that each stranded bunch, with the
exception of the center one, has a helical form of predetermined lay ratio, are known as a compound stranded bunch.  When the number of stranded bunches exceeds four they are arranged in concentric layers.  Alternate layers are usually stranded in opposite directions.
Cables are said to be bunched when two or more are contained within a single conduit, duct or grove, or, if not enclosed, are not separated from each other.  A stranded conductor in which all wires are twisted together in the same direction, and with the same lay throughout, is known as a bunched conductor.


Bunched Stranding -    A term applied to a number of wires twisted together in one direction in one operation without any regard to their geometric arrangement.
Bunching machine.    The double twist type machine has its capstan and take-up spool supported within a counter-weighted  frame or cradle carried with a rotating frame or flyer.  The rotating frame usually comprises two end plates with trunnions supported in pedestal bearings, the end plates being located longitudinally by three tubular members; a pair of guide pulleys
are mounted on each end plate.  Spools of individual wires are mounted on frames or creel stands located outside the machine.  Wires are drawn from these spools through a which is carried on the first pedestal bearing, thence through a forming die, around one pair of
guide pulleys where one twist is applied to the bunched wires, then through one of the tubular members of the rotating cage to the guide pulleys fixed to the end plate, and as the bunched wires leave the guide pulleys in their passage to the capstan the second twist is applied.  In one machine the wire passes through the machine twice - it is unwound from payoff spools, double twisted and reeled  on a fixed intermediate bobbin within the yoke of the machine; for the second run it is unreeled from the intermediate bobbin, again double twisted and then spooled.  Being of fixed size the intermediate bobbin can be a precision part of the machine to permit greatly increases speeds.
Burr.    The thin ridge of roughness left by cutting operations such as slitting, shearing, blanking or sawing.
Bus network.    A network topology in which all terminals are attached to a transmission medium serving as a bus.
Butt welding.    Welding of two wires end to end particularly to allow continuous drawing from one coil to another.
Butt Wrap    A spirally wrapped tape over a cable core where the trailing edge of one wrap just meets
the leading edge of the preceding wrap with neither overlap nor spacing.
Byte.    A unit of 8 bits.
C -    Centigrade or Celsius.
C.E.E. specifications.              Issued by the International Commission on Rules for the Approval of Electrical Equipment and obtainable from the British Standards Institute.  C.E.E. Publication 2 deals with rubber insulated cables and flexible cords.
Cable    An insulated conductor or twisted group of conductors used for the transmission of electrical energy.
Cable -    A term generally applied to the larger sizes of bare or weatherproofed  (covered) and insulated conductors, also applied to describe a number of insulated conductors twisted or grouped together.
Cable diameter gauge.    Cable can be measured as it emerges from the extruder by the optical method, in which a narrow band of parallel light scans the cable at 80 to 100 times per second and a photoelectric cell measures the relative time intervals of light and shadow as the light beam is interrupted periodically by the cable.  With the contact method the cable is measured between two synthetic sapphires and at a low contact pressure.  A controlled system can be arranged so that the haul-off speed of the cable is corrected so as to maintain constant the mean diameter of the cable.
Cable eccentricity gauge.    An electronically operated device for indicating continuously the degree of eccentricity of the conductor relative to the surround dielectric in extruded wires and cables.  A non- destructive test used to control production and for inspection on the final product.
Cable Filler -    A material used in a multiple-core conductor cable to occupy space and thus round up the cable, sometimes used to accomplish conductor spacing.
Cable Sheath -    The outer most covering of a cable providing overall protection.
Cable spinning machine.    Used in the aerial suspension of communication  and power cables to bind the cable into close contact with the supporting wire.
Cable,  filled    Cable construction in which the cable core is filled with a material that will prevent moisture from entering or passing through the cable.
Cable.    A term loosely applied to wire ropes, wire strands, manilla ropes and electric conductors.


An electric cable is a length of single insulated conductor (solid or stranded) or two or more such conductors each provided with its own insulation which are laid up together. The insulated conductor or conductors may or may not be provided with an overall mechanical protective covering. The various types of cable, insulating material and manufacturing processes are described in separate entries, e.g., aluminum cables, bunch, compression cable, impregnation, paper lapping machines, sheathing, strand, telephone cable, etc.
Cabling    The act of twisting together two or more insulated components by machine to form a
cable.
Cabling -    The act of twisting together two or more insulated components by machine to form a cable.
Cadmium    A bluish-white metal found mainly in zinc ores.  It is ductile and can be drawn into wire.
Cadmium coating.    Applied by electro-deposition  to provide a rust-proof coating on screws and nuts for many engineering accessories and aircraft parts, special springs, motor car electrical equipment, etc. Cadmium has very low contact potential difference in relation to aluminum and is thus used on steel components in contact with the aluminum. As compared with zinc, cadmium is not attacked by alkalis such as soaps and detergents; it also has a better resistance to marine conditions. Cadmium is not suitable for use on articles which may come into contact with food stuffs or drinking water, as the oxide is poisonous.  It should not be used on articles which maybe subject to temperatures in excess of 250 deg. C.
Cadmium copper.    Copper containing from 0.7 to 1.0 per cent cadmium.  The conductivity is upwards of 80 per cent.  IACS, and the tensile strength in the hard drawn condition about 50 per cent greater than that of copper.  Used for contact wire in electrical traction and similar purposes.

Cage.    The rotating frame or carriage of a stranding machine comprising a number of bobbin cradles supported between spaced discs which are usually mounted on a hollow mandrel. One end of the mandrel is supported in a pedestal bearing, and from this end it is usual to arrange the gear system to rotate the carriage.  Adjustable under-rollers are arranged under each carriage disc to support the carriage.  The other end of the mandrel terminates in a layplate to guide the wires or strands to the closing lie.
Calcium stearate.    Ground into a fine powder is used as a lubricant, particularly where the wire at a later stage will be undergoing a cold heading process.  Other materials, particularly lime are frequently added to give greater stability at wire drawing temperatures and pressures, while calcium stearate mixed with molybdenum disulphide has also been found satisfactory.
Calibration -    The process of setting a measurement instrument by use of standards.
Capacitance    The ratio of the electrostatic charge on a conductor to the potential difference between the conductors required to maintain that charge.
Capacitance.    Capacitance is that property of a system of conductors and dielectrics which permits the storage of electricity when potential differences exist between the conductors.
Capacitive Coupling    Electrical interaction between two conductors caused by the capacitance between them.
Capillary Action    The phenomenon of liquid rising in a small interstice due to surface tension.
Capstan.    A power driven parallel or slightly tapered drum, often taking the shape of a large pulley wheel, mounted on a horizontal shaft, used for pulling wire through a die at constant speed.  Sufficient turns are wrapped round the drum to prevent slipping.  Capstan life can be considerably increased - a factor of seven is claimed - by applying a coating of chrome oxide; specialists in such coatings point out that they can apply this coating again and again to extend the life of the capstan indefinitely.
Stepped drawing cones are in effect a number of drawing capstans mounted on one shaft and decreasing in size from the outside ones.  Ceramic drawing cones are increasingly used, sometimes manufactured in steel with easily replaceable ceramic rings for the contact surfaces.  On stranding and rope machinery the capstan hauls the rope


through the machine at constant speed.
Carat.    The measurement of weight for diamonds.  Equivalent to 0.2 gram.
Carbon steel.    Ordinary steel, containing from about 0.06 to 3 per cent of carbon, the word "carbon" being included merely to distinguish ordinary steel from alloy or special steels which contain other alloying metals as well as carbon.
Carburising.    A process in which steel is heated to about 900 deg. C. in an atmosphere containing hydrocarbons in the form of a gas such as methane, and maintained at that temperature until the desired weight of carbon has been introduced into the steel.
Carriage.    Part of a stranding machine also known as a cage (q.v.).
Carrier    In braiding, the moving part that carries the bobbin on the necessary path to form the braid.

Carrier frequency trunk cables.







Carrier sense multiple access with collision detection.

Star quad cable is normally used for these cables, the cables being employed in pairs one for transmission in each direction, but coaxial trunk cables have the great advantage of avoiding cross-talk between circuits. Conductors are usually of 1.0, 1.2 or 1.27 mm. dia. The frequency of each message is changed to a higher pitch so that up to 60 individual messages can be handled in one pair of wires, all at different carrier frequencies which are filtered out at the receiving end and restored to audio frequency. As more and more channels are put into use and frequencies are raised, cross-talk between circuits in the
same sheath increases an c can only be eliminated by expensive screening of individual circuits. This is not necessary with coaxial trunk cables (q.v.).
A technique used to control the transmission channel of a local area network to ensure that there is no conflict between terminal that wish to transmit.

Case-hardening.    Heat treatment of steel in which only the surface is hardened by the chemical addition of
carbon or nitrogen followed by heat-treatment.
Cast of wire.    The way in which waps of wire behave in a coal. If the waps when released do not conform to the required shape, this is known as bad cast; when the wires lie in uniform circles it is known as dead cast. Spiral cast denotes the tendency of the waps to spring out from the coil in spirals. Straight cast wire runs out approximately straight when unwound from the coil. To persuade the wire to coil itself to a required diameter after being drawn, a certain amount of off-set must be given to the die, sufficient to cause the wire to coil naturally in a circle slightly larger in diameter than the diameter of the block.
Cast Tape    A material which is formed directly into a tape by means of flowing or "casting" a solution
or dispersion of the film-forming material onto a suitable carrier, then removing the solvent - as opposed to skiving or slicing a block of material into a tape form.
Catenary wire.    The wire from which an overhead conductor is suspended by means of links. In a simple catenary-suspension construction, either a single contact wire or pair of contact wires is supported at intervals from a single longitudinal catenary. The correct lateral position of the contact wire or wires is generally retained by a pull off, steady-brace or bracket, attached to each supporting structure.
Cazzaniga process.    A hot dip galvanizing process in which the wire is led into a single degreasing and pickling tank, containing sodium hydroxide solution at 10-25 deg. Be; there is a separate compartment for each reel of wire and each compartment has a winding reel connected to the power supply, the electric circuit being completed through the wire to the zinc bath. The current heats the wire and the electric field surrounding the wire assists the pickling. The wire then travels for about 20 cm. through the air before going into the molten zinc. Oxidation during this period, when the wire reaches an annealing temperature of 650-700 deg. C., is prevented by an inert layer of molten soda on the wire. Heat conveyed by the wire is normally sufficient to maintain bath temperature and means of cooling the zinc are provided for high rates of working. Wiping and water quenching follows.  A maximum speed of 150 m./min. has been quoted.
Cellular polyethylene.    Consists of a system of small non-connected  gas cells distributed throughout polyethylene, and can be used as a dielectric material in the cable industry. It has a permittivity










Centro-symmetrical reflective optics.

intermediate between that of the gas and of polyethylene, ranging from 1.4 to 2.3 depending on the ratio of polyethylene to gas.  The tensile strength and elongation at break is from one-third to one-half that of solid polyethylene, but is fully adequate for cable use. Cellular polyethylene is also used for insulation of subscribers' telephone cables. It is extruded on standard units but if tandem drawing is not used the lines must be equipped with pre-heaters. Wire temperature and tension at the inlet to the head must be well controlled.
An optical technique in which a concave mirror is used to control coupling of light from one fiber to another.

Ceramic    Pertaining to a product made from inorganic, nonmetallic material fused or fired at high
temperature; used as an insulation in cables when extremely high temperatures are to be encountered.
Ceramic coating.                     Applied to winding wires where stability at high temperatures requires that conductors are given an oxidation resistance superior to that obtainable by an organic coating. Copper or nickel-clad copper wires are thoroughly degreased and chemically etched before a frit coat is applied. The frit is ground, dispersed in water and applied to the core wire by the
electro-phoretic  method, suitable coating thickness being obtained by adjusting the voltage. The frit consists of a lead-borosilicate  system, the same system being used for both copper and nickel-clad copper wires. In order to improve the adhesion, minute amounts of zinc oxide are added to the former and of copper oxide to the latter.
At a temperature of 1,000 deg. C. nitrogen gas is injected into the ceramic firing
furnace from the top, in order to adjust the atmosphere inside the furnace and to prevent excessive oxidation of the conductor material.
After the ceramic coating has been applied, the wires are completed by an additional layer of silicone or polyimide resin applied to the surface.
Ceramic drawing cones.    Wire-drawing step cones are available in alumina ceramic, which has a hardness between that of sapphire and diamond and is highly resistant to wear, abrasion and most chemicals, while it is dimensionally stable at high working temperatures. It can be worked to very close tolerances and reconditioning of the cones is simply carried out by grinding. Some step cones are manufactured in steal but with ceramic rings to combine the advantages of both materials; these rings are easily replaced.

Chalk applicator/Powder deposition.

When two or more cables are to be sheathed with plastic, they are first passed through an electrostatic powder depositing plant to coat them with french chalk to prevent them sticking together.  By imparting a high positive electrostatic charge to the powder a very uniform strongly adherent layer is applied with no free powder allowed to leave the unit.

Channel.                              A communications  path or the signal sent over the channel.   Through multiplexing several channels, voice channels can be transmitted over an optical channel.
Charpy impact test.               Carried out on a notched test piece, supported at both ends, the energy required to fracture the specimen by a blow from a striker being recorded. Detailed in B.S. 131.   See "Impact Test".
Cheese wire.    A hot-dip tin coated high tensile patented steel wire used for cutting cheese.  Size 0.6 mm.
Tensile strength 190 to 210 mm. square.
Cheese.    A quantity of wire or yarn which has been traverse wound on a reel or spool which has subsequently been removed.
Chromium alloys.    Some of the commoner chromium alloys include the following:
Chromium steel. Steel containing over 0.5 per cent chromium.
Chromium copper. Copper containing from 0.4 to 0.8 per cent chromium. Can be hardened and strengthened by heat treatment and has a conductivity upwards of 80 per cent I.A.C.S.
Chromium-molybdenum steel. An alloy containing from about 1 to 1.5 per cent chromium and 0.5 per cent of molybdenum.
Chromium nickel steel. A series of corrosion resistant alloys including stainless steel qualities. Stainless steel wires have excellent welding characteristics,  the 18 per center


chromium, 8 per cent nickel alloy being most widely used. The 25 per cent chromium, 12 per cent nickel quality, in addition to being highly resistant to corrosion, also has wide uses because it has exceptional resistance to scaling at temperatures up to 1,150 deg. C.
Chromium silicon steel. Low-alloy steels of this type are sometimes used for springs, an approximate composition being 1 per cent silicon and 0.40 per cent carbon.
Chromium vanadium steel. Often used for motor valve springs and other high-quality springs. Contains up to 1.5 per cent chromium and about 0.15 per cent vanadium.
Chromium plating.    Applications are (1) as a hard deposit for engineering purposes (2) in conjunction with nickel as a decorative/protective finish. Hard chromium is applied directly to the basis metal to give a surface which is extremely hard, highly resistant to abrasion, has an extremely low co-efficient of friction and possesses anti-seize properties. As a decorative/protective finish chromium is applied over an initial deposit of nickel. A typical chromium thickness is 0.25 to 0.8µm over 40µm of nickel. Deposition is made from a solution of chromium trioxide (chromic acid) containing about 1 per cent of a catalyst, usually sulphuric acid, at about 35 to 60 deg. C.
Circuit (Electric) -    A conductive path over which an electric charge can flow.

Circular Mil    A measurement used in determining the area of wire.  The area of a circle one one thousandth inches in diameter.
Circular mil (CM)                  A term used to define the cross-sectional  areas of conductors. It is an area equal to the area of a circle 1/1000 of an inch in diameter. As the number of circular mils increases, the size of a wire increases.
Circular Mil -    A unit of measure used to define the area of a wire. The area of a circle one one- thousandth inches in diameter.
Cladding    A method of applying a layer of metal over another metal, whereby, the junction of the two metals is continuously welded.
Cladding mode.    A mode confined to the cladding; a light ray that propagates in the cladding.
Cladding.    The outer concentric layer that surrounds the fiber core and has a lower index of refraction.
Closer reels.    As used in the wire rope trade. Are similar to laying up reels. See entry under reels. Closing machine.    A machine for making up strands into a wire rope. It is virtually a large type of strander. CMA -    Circular Mil Area.
Co-Polymer    A term used to designate that two or more monomers are polymerized together to form a
different material.
Coarse laid rope.    Rope formed from large wires. Also known as hard laid rope.
Coaxial    A cable configuration having two cylindrical conductors with coincidental axes, such as, conductor with a tubular shield surrounding the conductor and insulated from it.
Coaxial -    A cable configuration having two cylindrical conductors with coincidental axes, such as, conductor with a tubular shield surrounding one conductor and insulated from it.
Coaxial cables.    A central copper conductor which may be in the form of a tube made of interlocking copper strip provides the coaxial tube which is often held in position by  a series of regularly spaced insulated discs. The outer conductor, which acts as a screen, is reinforced by steel tapes. The coaxial pair can also be constructed by extruding polythene over a central copper conductor and applying an outer conductor of lapped copper tapes. Braided copper wires are used for the outer conductor of some radio frequency cables.  Coaxial cables may contain a single tube but they are usually in composite form containing two or more coaxial tubes with additional circuits of multiple twin and star quad. A paid of coaxial tubes can provide as many as 1,000 circuits.
Such a cable has no external field and is not susceptible to external fields from other sources.
Cogging.    The initial stages of a hot rolling process in which the chief object is to reduce the cross- section as expeditiously as possible.
Coil taping machine.    A machine used for binding the tape on electrical field and similar coils, for insulation


purposes.
Coil wrapping machines.    Designed to wrap coils and straight bundles of wire or cable entirely mechanically, using paper, hessian, cellulose film, etc. The machine is loaded with a roll of wrapping material of suitable width, and this is taken automatically through the "eye" of the coil and round the wire so that the coil is evenly and tightly wrapped in a matter of seconds.  These machines are also capable of gumming the paper so that the wrapping does not unravel.
Coiling units.    The demand for wire in long lengths in coil coupled with increasing speeds of drawing has brought about the introduction of a number of stationary coiling machines which can be coupled to the wire-drawing machine or used as a take-up for such processes as galvanizing, patenting, extruding, etc., enabling high-speed production to continue during the coil removal period. See entries for Draw-pack, gravity block, and Rotolay.
Cold Bend -    Generally refers to a test to determine cable or wire characteristics at low temperatures.
Cold Flow    Permanent deformation of the insulation due to mechanical forces without the aid of heat softening of the insulating material.
Cold Joint    A soldered joint made with insufficient heat.
Cold Work    The hardening and embrittlement of a metal by repeated reflexing action.
Cold working.    Plastic deformation at a temperature low enough to create work hardening. The tensile strength of wire rises with increasing amount of cold working by drawing, and when the tensile reaches a point where the force needed to pull the wire through the die is greater than the load the drawn metal can withstand, heat treatment is necessary to soften the wire before the further drawing can be undertaken. The amount of reduction which can be carried out on steel wire before heat treatment is necessary depends largely on the carbon content.
Color Code    A color system for circuit identification by use of solid colors, tracers, braids, surface
printing, etc.
Color Code -    Color code is the use of different colored insulated wires in a multi-conductor  cable for purposes of identification.
Compact Conductor -    A concentric stranded conductor which after stranding and on subsequent layers in a multiple layered cable, is passed through a closing die or roller die to reduce the diameter approximately 10%, thus eliminating the normal interstices in the cable.
Compacted conductor.    A stranded conductor in which the air space at the interstices of the wires is reduced by passing the conductor through rolls on a die to crush the wire.

Compacted strand.
Composite Conductor
-


A composite conductor consists of two or more strands of different metals, such as aluminum and steel, or copper and steel.  i.e.:  ACSR, ACAR, AWAC.

Composite conductor.    A conductor consisting throughout its length of two or more metal conductors providing parallel paths sharing the load. A composite cable is one in which the gauge of the conductors,

and/or the type of construction is not the same throughout its cross-section.
Compound                      A term used to designate an insulating and jacketing material made by mixing two or more ingredients.  To compound: the mixing together of two or more different material to make one material.
Compound -    An insulating or jacketing material made by mixing two or more ingredients.

Compressed
Conductor -

A concentric stranded conductor which after stranding, or on subsequent layers of a multiple layered conductor, is passed through a die to reduce the overall diameter approximately 3%.


Compression cable.    A mass-impregnated  pressure cable in which the pressure medium is not in contact with the dielectric. In these external pressure cables, the insulated cores are constructed in the same way as for solid cables and each core is usually covered with a polythene or thin lead sheath, which serves as a diaphragm. One or more cores are then enclosed in an outer protective covering.

Concentrator.    A multiport repeater.
Concentric cable.    A cable containing two or more separate conductors, arranged concentrically, with insulation between them. Unless otherwise qualified, the term denotes a cable consisting of two conductors only.

Concentric lay conductor.

A single conductor composed of a central core surrounded by one or more helically laid wires. Each of these succeeding layers is applied with an opposite direction of twist. The number of wires laid up the center wire is six, and each succeeding layer consists of six additional wires so that the number of wires in the strands are 7, 19,37,61, etc.


Concentric Neutral -    A number of wires concentrically stranded about a cable for use as a neutral.
Concentric strand.    A strand that consists of a central wire or core surrounded by one or more layers of spirally laid wires. Each layer after the first has six more strands than the preceding layer and is applied in a direction opposite to that of the layer under it.
Concentric Stranding    A group of uninsulated wires twisted so as to contain a center core with one or more
distinct layers of spirally wrapped, uninsulated wires laid overall to form a single conductor.  When more than one layer is present each layer must have a different lay length.
Concentric Stranding -    A group of uninsulated wires twisted so as to contain a center core with one or more distinct layers of spirally wrapped, uninsulated wires laid overall to form a single conductor.
Concentric-Lay-Cable -    A concentric-lay conductor or a multiple-conductor cable composed of a central core surrounded by one or more layers of helically laid conductors.
Concentricity    In a wire or cable, the measurement of the location of the center of the conductor with respect to the geometric center of the circular insulation.
Conductance    A measure of the ability of a conductor configuration to conduct an electrical charge
Conductance is a ratio of the current flow to the potential difference causing the current flow.
Conductivity    A term used in describing the capability of a material to carry an electrical charge.
Usually expressed as a percentage of copper conductivity - copper being one hundred
(100%) percent.  Conductivity is expressed for a standard configuration of conductor.
Conductivity -    A term used in describing the capability of a conductor to carry electric current.  Usually expressed as a percent of a soft copper conductor which is defined as being 100% conductive.
Conductivity of copper.    Expressed as a percentage of the IACS (International Annealed Copper Standard).  See "IACS". The effect of impurities in high conductivity copper depends on their nature and concentration. Small quantities of silver and cadmium have comparatively little effect on conductivity, but 0.05 per cent of phosphorus reduces the conductivity to about 70 percent IACS, and 0.4 percent of arsenic reduces it to 40-50 percent IACS, while silicon is also particularly harmful. Cold working decreases the conductivity of high conductivity copper and when it is in the fully hard-drawn condition, its conductivity is about 3 percent lower than when annealed.
Conductor    Any material capable of carrying an electrical charge easily.
Conductor -    A wire or combination of wires not insulated from one another, suitable for carrying an electric current.  A conductor may be used bare or insulated.
Conductor Shield -    (see Strand Shield).

Conductor.    The conducting portion of a cable or core. It is made up of a number of bare copper or aluminum wires, stranded or bunched, the use of the latter usually being confined to the smaller flexible cables. Conductors are manufactured on sun and planet stranders, tubular stranders, fixed bobbin stranders and bunching machines (q.v.) See also "Bunch", and "Stranded Conductors".
Conduit -    Channel for holding wires and cables, made of metal or an insulating material, usually circular in cross section.  Common varieties of conduit are EMT (electrical metallic


tubing) and Rigid conduit, which are both circular and metal, resembling metallic pipe.
Conform.    This is essentially a mechanical extrusion process. A hard wheel having a groove of approximately rectangular section, has, closely engaging the groove, a stationary shoe incorporating an end stop in which are one or more apertures. These may be of circular or non-circular form.
The wheel is driven, material is fed into the open end of the shoe, friction pulls the material forward, compresses it into the closed end creating pressures in the material
which extrudes through the aperture. Scap ends, powders or specially selected stock can be fed in continuously, and therefore extruded continuously.  Overall cold reductions in
excess of 25:1 in copper are possible.
The process is more suitable for nonferrous materials, but work is being carried out at the United Kingdom Atomic Energy Authority, inventors of the process, on many metals.
Connector -    A mechanism used to unite two pieces of cable or cable to an apparatus, both physically and electrically.
connector.    A device for making connectable/disconnectable connections of a fiber to another fiber, source, detector, or other devices.
Constantan.    An alloy of 55 percent copper and 45 percent nickel used in thermocouples with copper in the temperature range - 169 deg.C. to 386 deg.C. Temperature coefficient of electrical resistivity is 0.0002/deg.C.
Contact wire.    An overhead conductor form which electric power is supplied to electrically equipped vehicles. also known as trolley wire.
Continuity Check -    A test performed on a length of finished wire or cable to determine if the electrical current flows continuously throughout the length.  Each conductor may also be checked against each other to ascertain that no short exists
Continuous casting.    In a plant for the production of billets to be rolled into wire rod, molten steel is teemed from the ladle into a curved copper mold from which a solidified strand of steel is drawn and made to follow a curved roller path while it is cooled by means of water sprays. The machine will cast any section with dimensions between 65 and 120 mm. and is fed from one 25 ton electric arc furnace. Maximum casting sped is nearly 7 m. per min. The machine, designed for twin-strand operation with provision for a third strand to be added, has a total height of about 6 m. from the floor to the casting platform. A somewhat similar process for continuous casting of copper alloy wire rods, particularly brass and phosphor bronze, is being increasingly used. One manufacturer has perfected a process for the direct continuous conversion of copper, tin and zinc into copper alloy wire rods. Accurately weighed batches of the raw materials are charged at intervals into a completely automatic plant where they are melted, alloyed and cast into eight 12.7 mm. dia. wire rods which
flow continuously in virtually endless lengths from the underside of the plant. They are cut into convenient lengths to produce large coils weighing up to a ton. The Properzi continuous casting process for aluminum wire rod is described under the entry for Properzi process. A similar process has been developed in the USA for continuous casting of
copper wire rod. Another continuous casting process from the USA is the dip form process.
Continuous coiling.    See entry for stationary blocks.
Continuous furnace.    One in which the process is continuous by means of a conveyor or by passing individual strands of wire through a fixed furnace.
Continuous mill.    A series of rolling mill stands in which the material is formed by successive sets of rolls, and in which several stands may be simultaneously in use to continuously reduce the section.

Continuous
Vulcanization  (CV)-

.A continuous, in-line process whereby a wire has an extruded covering applied, is then passed through a tube containing such temperatures and pressures as are necessary to complete vulcanization.

Contour cable.    A ribbon-like flat and flexible cable developed for use in missiles, and also used in data processing, computers, telephone and signal circuits and wherever multi-circuits are to be


run in confined spaces. Very flat metallic strips are embedded side by side in a plastic dielectric ribbon which thus carries up to 40 separate conductors. A typical cable is about as thick as a postcard. For aircraft use contour cable 0.3 mm. thick is equivalent to conventional wire of 1.7 mm. dia. and the contour cable can be stuck to the inner wall of the aircraft, shaping itself to the fuselage contours and bending round and equipment in its way. There is also a considerable weight saving.
Contrahelical    A term meaning the application of two or more layers of spirally twisted, served, or
wrapped material where each successive layer is wrapped in the opposite direction to the preceding layer.
Control Cable    A multiconductor  cable made for operation in control or signal circuits, usually flexible, relatively small in size, and with relatively small current ratings.
Control Cable -    A multiconductor  cable made for operating in control or signal circuits, usually flexible, relatively small in size, and with relatively small current rating.

Controlled atmosphere.    A gas or mixture of gases having specific or general properties, known either to cause or prevent certain gas-to-metal reactions occurring during heat treatment. Oxygen, carbon dioxide and water vapor all have an oxidizing and decarburising effect. Hydrogen, in the presence of water vapor can give rise to excessive decaraburization.   Other gaseous constituents, carbon monoxide and methane both have a reducing and carburizing effect, depending upon temperature and the concentration of other gases present at the same time. Dry hydrogen has a strongly reducing effect but is otherwise inert in so far as surface changes are concerned. Nitrogen, which forms the major constituent of the inert or protective type atmospheres has no surface effect. Most controlled or prepared atmospheres are produced from a consistent source of hydro-carbon gas, i.e. natural gas (methane), vaporized propane or butane, by a process of total or partial combustion in air in the case of the exothermic type atmospheres or by passing a mixture of the reaction fuel and air over a heated catalyst in the case of the endothermic type atmospheres.
Convection    A conveying or transference of heat or electricity by moving particles of matter.

Coolants for wire- drawing.

See entry for wet lubricants under the heading "Lubricants".

Copper (Cu).    A highly malleable and ductile reddish metal with high electrical and heat conductivity,
which forms the basis of brasses and bronzes. Widely used in the pure form wherever high electrical conductivity is required. Agreed standards for the electrical properties of high conductivity copper wire are laid down in the International Annealed Copper Standard and the conductivity of copper and its alloys is referred to the I.A.C.S. on the percentage principle.  alloys of copper are frequently used for electrical purposes because pure copper has not the mechanical strength necessary for some purposes, and this consideration outweighs the loss of electrical conductivity.
Cast copper has a tensile strength of about 155 N/mm square, but his is increased when cold working modifies its grain structure. Hard-drawn copper has a tensile strength of about 430 N/mm square or over 460  N/mm square for smaller sizes. Annealed high conductivity copper wire has a tensile strength of about 220 N/mm square. See "Conductivity of Copper."
See also entries for deoxidized copper, electrolytic copper, fire refined copper, oxygen- free copper and tough pitch copper.
Pickling of hot-worked copper is essential before drawing, but this only removes oxide. For fine wire manufacture, and for enameling quality wire, where surface imperfections
are particularly deleterious, shaving of the rod at an intermediate size is commonly practiced.  For such purposes, hot rolling is normally terminated at about 12 mm.
diameter.  The wire is then "shaved", during which approximately 0.3-0.4 mm. is removed from the surface. The shaved rod is then cold drawn to final gauge.
Beryllium copper. (Sometimes known as beryllium bronze) composed essentially of copper with beryllium and, because of its hardness, high strength and resistance to


corrosion, used for springs of many types, as molds for plastics, as resistance welding electrodes, and for non-sparking tools.
Blister copper. An impure form of copper produced by blowing air through molten copper matte. During the conversion process, sulphur, iron and other impurities are oxidized. The copper content is normally about 98 percent.
Cathode. A rough flat refinery shape made by electrolytic deposition and normally used for remelting.
Cement copper. An impure, finely divided mixture of copper and copper oxide obtained by precipitation of copper usually by iron (cementation) from an aqueous solution of copper compounds. The copper content, dry basis, varies widely, usually in a range of approximately 50 to 85 percent.

Chromium copper. Mainly used for resistance welding electrodes.
Copper-silicon  and silicon brass consisting essentially of copper or bras and silicon and having high strength and resistance to corrosion. It is used, e.g., for the manufacture of storage tanks, bolts and fasteners.
Copper wire. Rolled, extruded or drawn products of solid section of any cross-sectional shape, of which no cross-sectional  dimension exceeds 6 mm.
Copper-zinc alloys containing small quantities of other metals form special brasses, with characteristic properties. Special brasses include: high-tensile brass (often known as manganese bronze), used in ship-building, as well as leaded brasses, iron brass and aluminum bras.
Deoxidized copper. Copper free from copper (1) oxide and containing controlled amounts of metallic or metalloidal deoxidizes, such as phosphorus, lithium, boron, calcium. The phosphorus deoxidized copper is most commonly used.
Oxygen-free copper. Copper containing neither copper (1) oxide nor any residue of deoxidizes.
Refined copper. Is cast into ingots or ingot-bars for remelting (e.g., for alloying purposes) or into wire-bars, slabs for rolling, billets, (including those of circular cross- section) and similar forms for rolling, extruding, drawing or forging into plates, sheets, strip, wire, tubes and other semi-wrought products. Copper partially refined by complete fusion is cast into anodes for further refining by electrolysis. They should not be confused with anodes for electro-copper-plating.
Tough pitch copper. Copper containing a controlled amount of oxygen in  the form of copper (1) oxide.
Unalloyed coppers. Commercially pure metal to which no elements are intentionally added except for oxygen or the elements required for deoxidization, i.e. phosphorus, lithium, calcium, boron, etc. The minimum copper content shall be 99.85 percent.  For use in foundries a minimum copper content of 99.5 percent may be permitted.
Copper alloy wires.    Have very good mechanical properties and are easily cold worked.  Used for a wide variety of products and for electrical purposes where pure copper does not have sufficient mechanical strength. Depending on degree of cold working, tensile strengths of up to 800
N/mm. square are attainable, and may be considerably higher in the case of heat-treated beryllium copper.  Other advantages include high resistance to a very wide range of corrosive environments, high thermal and electrical conductivities, good machinability, non-magnetic properties, and ease of polishing and plating. They have lower elastic moduli than ferrous materials, and this is particularly advantageous in spring applications where a large deflection under a small load is desirable.
Reductions, heat treatment and drawing speeds vary widely due to the differing properties of the many alloys used. Brasses with about 63 percent copper and usual commercial percentages of lead can be given about 20 percent reduction in multiple machines and up to 40 percent in single die machines, with a total of about 80 percent reduction between anneals; more ductile grades will withstand more cold work.


Alloyed coppers are coppers containing one or more of the elements listed in the following table, in a content no exceeding the limits shown (classification principle to be applied in case of doubt and not considered as a specification according to which products can be ordered, supplied or tested). The total content of alloying elements shall not exceed
2.5 percent

Element    Limiting content
   % by mass
Ag silver    0.25
As Arsenic    0.5
Cd cadmium    1.3
Cr chromium    1.4
Mg magnesium    0.8
Pb lead    1.5
S sulpur    0.7
Sn tin    0.8
Te tellurium    0.8
Zn Zinc    1.0
Zr zirconium    0.3
Other elements *, each    0.3








Copper clad aluminum wire.

* Other elements are, for example, Al,Be,Co,Fe,Mn,  Ni, Si.
Copy alloys are metallic substances in which copper predominate by mass over each of the alloying elements provided:
(a)  that the content by mass of at least one alloying element shall    be greater than the
limits shown in the table, or
(b)  that if elements present do not exceed the limits shown in the table their total content by mass shall be greater than 2.5 percent.
Produced by a patented bonding process into redraw rod of about 8 mm. dia. and then drawn to any desired gauge, including fine wire, using standard copper wire-drawing practice. A final in-line resistance anneal is recommended after drawing and copper/aluminum  can be resistance annealed on the same equipment used to draw and resistance anneal copper. For high frequency applications, only the outer surface is functionally used and therefore copper/aluminum  can be substituted size-for-size for copper with equivalent performance.  For mains frequency uses, the important factor is the ability of copper to provide completely reliable electrical connections without the special techniques developed for aluminum; these and other problems of aluminum oxides and corrosive products are avoided.  For similar current-carrying  capacity, it is necessary to
use a larger copper/aluminum  conductor than would be required if a solid copper one were being used.

Copper clad steel wire.    Copper covered steel used for electrical conductors in circumstances necessitating high tensile strength. In drawing, material is reduced without change in cross-sectional proportions of the two metals.

Copper coating of steel wire.

Steel wire is coppered to prevent rusting and also to provide a lubricant for subsequent drawing.  A residual copper coating is sometimes required for bedding and seating wire, welding rods and wire for subsequent plating. The copper is usually chemically deposited by a simple displacement process based on copper sulphate with various additives such as chloride, inhibitors and wetting agents.  Subsequent drawing is essential to attach the copper firmly to the base metal by the compression effect of drawing.  Copper coating can be carried out either (1) by etching and dipping in batches of coils or (2) by in-line


processing in continuous strand using a 3 to 5 percent sulphate of copper solution in a line similar to a strand phosphating line; coppering and phosphating facilities can be provided in the same line.  It is easier to control depth of copper coat by electrolytically depositing and a greater thickness of copper can be built up by this method, but this is not necessary
if only a light coat is required. The normal solution dip should be adequate, this being
simpler and cheaper to apply.
For materials to finish in diameters up to 2.5 mm. the lime coated method is suitable. After cleaning and coppering, the wire is limed, then dried-off in a suitable oven at a temperature of approximately 250 deg. C. In drawing, general practice is to give a first or roughing draft through grease, followed by further drafting in wet solution.  It should not be overlooked in coppered wire liming that the lime solution is more rapidly fouled than when employed for ordinary wire immersion, thus necessitating more frequent renewal.
For finishing to diameters smaller than 2.5 mm. where base or starting size is 3 mm. or finer, the method of storing the wire under water after cleaning, and coppering as needed for drawing can be used, or the wire can be coppered and then placed quickly in a wet lubricant close to the drawing machine.  This cuts out the drying process, a matter of difficulty at times with the finer sizes, particularly if the oven is used for the drying of rods and thick wires.  Care should be taken that the material is not permitted to dry during transfer from washing to immersion in water storage tanks, otherwise the copper coat may peel during passage through the die.
Many good compositions are available for dipping and as a lubricant for subsequent drawing; the use of these is probably more economic than making up solutions.  Two such proprietary compounds are described in the entries for Curobond and Cuprodine. A suitable made-up solution consists of 1.8 kg. copper sulphate, 6.8 lit. sulphuric acid, 3.4
lit. hydrochloric acid and 45 lit. water. A wetting agent should be added, and 227 gm. of
sal ammoniac, dissolved in about one quart of hot water, will improve the binding properties of the coat if it is added to the solution before use.
Another copper immersion coating solution is based on the tetrasodium salt of ethylane, diamine, tetra-acetic acid (E.D.T.A.) made up in the proportion: copper sulphate 37 gm./lit., tetra-sodium E.D.T.A. 92.5 gm/lit, and wetting agent 0.5 gm./lit  It is used at a 40 to 60 deg. C. and pH 4-5, for a treatment time of from 1 to 5 minutes, during which time it will deposit 0.00002 to 0.00003 mm. of copper. The iron which is dissolved can be removed from the solution by adding excess copper sulphate and raising the pH when iron will precipitate as hydroxide.
If the material is to be sold "as drawn", the lubricant in the last one or two die boxes may be of a wet soap, oil or emulsion type to brighten the copper finish.  For a really
bright finish, wire is usually drawn in a wet drawing machine.  Inhibiting dips are available to prolong the stain-free life of the copper coating.
Where a fully coppered coat is required, the wire cannot be drawn more than about 30 percent reduction after coppering or the resultant coating would be insufficient unless special heavy copper coats are used. In the case of bright wire, if no discoloration is permitted, the degree of wet drawing is limited to about 20 percent by the necessary lack of coating and weakness of lubricant.
When copper coated wire has been reduced by about 85 percent in cross-sectional  area, the residual coating is thin and lacks the luster of drawn coppered wire with a heavier coating. To restore this appearance it is not uncommon to pass copper coated and drawn wire through a short in-line coppering bath prior to a final drawing pass.  If this is to be done, the earlier drawing operations should be carried out with a soluble soap such as sodium stearate. The residue of this can then be removed in a sheet cleaning zone prior to final copper coating. For such in-line treatments, both de-soaping and copper coating operations are carried out in a few seconds. In certain cases the flash re-coppering operation is carried out in a small tank attached to the drawing machine.
When wire is required to have a copper tint as distinct from a deep copper color this is


known as liquored wire (q.v.).
Copper plating.    For the electro-deposition  of copper, for example, on springs, the material to be coated forms the cathode in a solution of copper cyanide and potassium cyanide and rods of pure electrolytic copper form the anode.  Other plating bath compositions,  based on copper sulphate, copper  and copper pyrophosphate  are also available.
Copper wire bars.    Horizontal cast tough-pitch copper wire bars about 100 x 100 mm. cross-section by about
1.2 m. long and weighing about 113 to 125 kg. are used for the production of wire rod, although these are rapidly being replaced by the continuous casting and rolling processes. These allow continuos rod production (unlike rods produced from wire bars) into coil weights of up to 5 tons. The top surface of a wire bar has a higher oxygen content than the remainder, and this surface section may be machined off when high quality fine wire is being produced. The bar is heated to about 800-850 deg. C. before being rolled into wire rod of 6.4 to 19 mm. dia.
Copper wire rods.    Usually of 6 to 12 mm. dia., or alternatively 8 to 10 mm. square section with rounded corners.  Copper wire can be produced by hot rolling electrolytically refined wire bars of about 100 mm. square section weighing about 115 kg. after heating them to about 800-850 deg. C. Sometimes also produced by extrusion or a combination of extrusion and cold rolling.  When carefully controlled, the rod complies with the specification requirements for cable manufacture, but were a high-quality surface finish is required the surface of the rod has to be removed as described in the entry for shaving copper rod.  The pass sequences based on alternating square and oval cross-sections used for many years in manually repeated copper rod rolling mills have proved less successful in fully automatic mills owing to difficulties in obtaining correct entry of oval sections into square grooves when a wider gap has to be left between guiding block and grooves to allow the rod to find its way by its own force.
A continuous casting process based on the Properzi principle has been developed in the U.S.A. for production of copper wire rod and is now being used in over 20 plants throughout the world.  Another development in the U.S.A. is the dip forming method in which shaved copper rod is passed vertically upwards through a crucible of molten copper, emerging as a much thicker rod which passes up a cooling tower and then to a rolling mill.
In the direct electrodeposition  process, copper wire rod is electro-formed from cast refinery anodes and subsequently cold formed to wire. Rod can be successfully produced for cold rolling and drawing into wire which is as good as that from commercial electrolytic wire bars from the point of view of electrical conductivity, the wrap test and the twist test.
Copper alloy wire rods.  A British manufacturer has perfected a process for direct continuous conversion of molten copper alloy into wire rods of 12.7 mm. dia. in coils weighting up to 1 ton. a mall number of manufacturers use continuous casting for alloys including 70/30 and 80/20 brass, producing rod up to 19 mm. dia., claimed to be free from inclusions and other metallurgical defects and available in heavy coils.
Extrusion is used to produce a high-quality rod from alloys such as the leaded brasses with good  hot-working characteristics.   Usual extruded diameter is 6.4 to 9.7 mm. ready for cold drawing. Extrusion followed by cold rolling is used for high copper alloy such as
70/30 brass and the gilding metals.  Extruded 19 to 22 mm. dia. rod is cold rolled to 8 mm.
square section, usually in a 10 or 12 stand tandem rod rolling mill.  Hot rolling followed by similar cold rolling is also used for brasses containing over about 70 percent copper. Tin bronzes or phosphor bronzes are produced by cold rolling with annealing between each pass, or increasingly by continuos casting. See also entry for hydrostatic extrusion.
Copper wire.    Widely used for electrical purposes and also in many general applications principally on account of its softness in the annealed condition and its subsequent ability to withstand a severe amount of deformation, and to conduct heat efficiently. Tensile strength ranges from about 220 N/mm square (annealed) to 460 N/mm square (hard drawn). Copper wire
for cable conductors is annealed in a protective atmosphere at 250 to 450 deg. C. for about


2 hours as cable conductors need to be ductile.  See also "Lubricants," "Copper Clad
Aluminum Wire," "Springiness of Copper Wire."
Copper wire is invariably wet drawn on multi-hole machines which permit slip to occur between wire and capstan.  Particularly on rod breakdown and other capstan type
machines it is important to keep slip to a minimum to avoid the capstan rings wearing into a series of concentric grooves.  The wire has to transfer from groove to groove and in doing so becomes damaged. This trouble is minimized on cone type machines as the wire is made to traverse the face of the cones.
Superfine copper wire, as fine as 3 microns (0.003 mm.) or even less, is now being produced by slowly passing a piece of glass tubing, containing a length of copper wire, down through a radio frequency induction heating coil.  A globule of molten copper is maintained at the lower end of the glass tube and the hot end of the glass is drawn out after being cooled by water sprays it is attached to a spool, whereupon lengths of up to
1,000 meters of copper or manganin wire are drawn as a continuous thread inside the glass at speeds of about 100 meters per min. The glass coating obviates the need for a separate insulting operation, while the glass is able to withstand a D.C. voltage of about 5,000
volts. The mechanical properties of the wire are, in fact, those of the glass itself and it is
surprisingly flexible, so that sizes below 10 microns can be bent round a radius of about 1 mm.
Copperweld (CW) -    A copper covering over a high strength steel core used for its corrosion resistance, high electrical conductivity, and ductility.  Copperweld Enterprises.
Cord    A small, very flexible insulated cable.
Cord -    A small, flexible, multiple-conductor cable.  i.e.:  Type SJ, ST.

Cord Sets -    Portable cords, fitted with any type of wiring device at one or both ends.
Cord.    A term applied both to small sizes of wire rope and to small conductors.  A flexible cord is a flexible cable having conductors of small cross-sectional  area. Two flexible cords
twisted together are known as twin flexible cord.
Core    In cables, a term used to denote a component or assembly of components over which other materials are applied, such as, additional components, shield, sheath or armor.
Core -    In cables, a term used to denote a component or assembly of components over which additional components, such as shield, sheath, or armor, are applied.
Core of a wire rope.    core member of a wire rope about which the strands are laid.  It may be fiber, a wire strand or an independent wire rope.  The central fiber core in a wire rope must support the wire strands so that there is no undue mutual abrasion of the wires in adjacent strands and must also provide an elastic bed to allow relative displacement and deformation of the wire strands when the rope is flexed around a sheave. Fiber cores should be as nearly as
possible free from salt, acid and moisture before they are impregnated with lubricant.  As well as providing central lubrication for the wires of the rope, saturation of dry fiber cores with lubricant also prevents reabsorption of moisture by the core.  Cores made from soft fiber such as hemp and jute are normally larger than those made from hard fibers such as Manila hemp and African sisal; hard laid cores may be smaller in size than soft laid cores.
Core tubes.    Another name for the extruder tips used when extruding a plastic or rubber insulation coating on wire with an extrusion machine.  Alternatively, the tube into which the die top screws.
Core wire.    (1) Employed as core or foundation wire in certain types of wire rope construction. Drawn to various sizes. Finish, usually fully annealed for ordinary strand ropes, but for certain constructions a hard, high carbon wire, finished to a specified tensile stress, is employed. (2) The wire used in the construction of sand cores placed in molds for the production of castings.  This is a low

carbon steel wire, fully annealed at finished size and with a black annealed finish or cleaned and oiled.


Core.    The central, light-carrying part of an optical fiber; it has an index of refraction higher than that of the surrounding cladding.
Cored dies.    Tungsten carbide die blanks which are prepared with a performed hold before sintering so reducing drilling time considerably.  The smallest holes preformed are about 0.004-5 in.; below this, holes have to be drilled in the solid blank.
Corona    A discharge due to ionization of a gas (usually air) due to a potential gradient exceeding a
certain critical value.
Corona -    The discharge of electric current from a conductor causing the ionization of the surrounding air as evidenced by a luminous glow, a hissing sound and the odor of ozone.

Corona Initiation
Point

The critical value in the application of an electrical potential where corona is first noticed by the detection device.

Corrosion    The process or result of a material being eaten or worn away, usually by chemical reaction.
Corrosion -    The process of result of a material being eaten or worn away, usually by chemical reaction.
Coupler.    A multiport device used to distribute optical power.
Cover wires.    The outer layer of wires in a rope.
Covering -    A material applied over a conductor generally for weather protection.
Creel stand.    A frame for holding bobbins of yarn or fine wire so disposed that there is a clear lead for each yarn or wire to a machine, e.g. for bunching.
Creep limit.    A stress which will produce a stated deformation or rate of deformation at a specified temperature and time or over a specified period.
Creep.    Plastic deformation which proceeds slowly and continuously when stress is applied at elevated temperatures.  In steel, creep is negligible below about 300 deg. C.
Crimp Termination    A wire termination that is applied by physical pressure of terminal to wire.
Crimping machine.    A machine for bending lengths of wire into crimps or corrugations by passing them between the teeth of two crimping wheels, so that the wires keep in position when formed into mesh. Originally all machines were operated by a handle on a flywheel which drove
the crimping wheels through gearing.  These machines are now power driven, and the most commonly used pairs of wheels are permanently mounted on the driving shaft sot hat
fewer wheel changes are necessary.  Guarding is very important.
Critical cooling rate.    The rate of cooling required to suppress phase changes. The term is most usually applied to the rate of quenching required to produce a martensitic structure in the hardening of steel.  The critical cooling rate in patenting is that necessary to provide minimum pearlitic spacing.
Critical range.    The temperature range in which a constitutional change occurs on heating or cooling a metal in the solid state.  Also known as the transformation range.
Cross Sectional Area    The area of the cut surface of an object cut at right angles to the length of the object.
Cross Talk    Electrical interference between two adjacent insulated conductors whereby a signal in one of the conductors will be picked up by the adjacent conductor.
Cross-linked    Inter molecular bonds produced between long chain molecules in a material to increase
molecular size by chemical or electron bombardment means, resulting in a change in physical properties in the material - usually improved properties.

Cross-linked polyethylene.

A dielectric material used for insulating and jacketing.

Cross-Sectional  Area -    The area of an object exposed by cutting it perpendicular to its longitudinal plane.
Crosslinked -                      Intermolecular  bonds produced between long chain molecules in a material to increase molecular size by chemical or electron bombardment, resulting in a change in physical properties in the material, usually improved properties.
Crow's feet.    Cracks on the surface of copper wire which were originally thought to be due to vibration effects caused by the use of heavy reductions in dies having unsuitable angles, so that the in going wire was damaged by contact with the mouth of the die.  It is now realized that the original cast surface of the horizontal-cast  bars has a tremendous influence.  With modern control methods the incidence of the "crow's foot" type of surface fracture is a rarity.  It is caused by the presence of more cuprous oxide near the surface of horizontally


cast wire bars than elsewhere, depending on the difference in oxygen concentration across the section and not on the average concentration in the material as a whole.  Both strongly oxidizing and strongly reducing atmospheres in the wire-bar reheating furnace promote the defect.
Crown.    Increased thickness in the center of strip or sheet as compared with the thickness at the edge.
Crystalline fracture.    All fractures are crystalline, but this term is generally applied only to those fractures characterized by a lack of visible plastic deformation.
CSMA/CD.    Carrier sense multiple access with collision detection.
CSR.    Centro-symmetrical reflective optics.
Cu -    Copper

Cup and cone fracture.    A fracture which gives a pointed cup on one broken piece and a cone-like shape in the other.
Cupping.    A tendency of defective wire to break prematurely with a cup fracture; may be caused by segregation resulting in a hard brittle center and a more ductile exterior, or by reedy wire core and small enclosed pipe.  It is due to the use of ides with acute angles and short bearing surfaces, so that the wire is not cold worked evenly throughout the cross-section, the outer skin being worked more than the core.  This ultimately results in the central portion of the wire developing internal fractures of a cup and cone nature - hence the term "cuppy" wire.  It is a common experience that the defect is observed only at a late stage of wire production and not at the particular die which is defective.
Cupro-nickels.    Alloys consisting essentially of copper and nickel.  Among the most important cupro- nickels in wire form are those containing from 55 to 60 percent copper, the remainder being nickel. These are characterized by high specific resistance with negligible temperature coefficient.  They are used for fixed resistances in electrical instruments.
80/20 and 70/30 cupro-nickels are supplied on spools for inert-gas shielded metal arc welding.

Current Carrying
Capacity
Current Carrying
Capacity -

The current a conductor of given size is capable of carrying safely without exceeding its own insulation and jacket temperature limitations.
The current a conductor of a given size is capable of carrying safely without exceeding its own temperature limitations, at a defined set of conditions.

Current Penetration    The depth a current of a given frequency will penetrate into the surface of a conductor carrying the current.

Cut-Through
Resistance

The ability of a material to withstand mechanical pressure, usually a sharp edge or prescribed radius, without separation.


Cutoff wavelength.    For a single-mode fiber, the wavelength above which the fiber exhibits single-mode operation.

CV-Continuous
Vulcanization

Simultaneous extrusion and vulcanization of wire coating materials.

CW -    Copperweld.
Dark current.    The thermally induced current that exists in a photodiode in the absence of incident optical power.
Data rate.    The number of bits of information in a transmission system, expressed in bits per second
(bps), and which may or may not be equal to the signal or baud rate.
dB    Decibel.
dBµ    Decibel referenced to a microwatt. dBm    Decibel referenced to a milliwatt. DBWP -    Double braided weatherproof cable.
Dead block.    A fixed block on which wire is fed by a disc or arm which rotates round the block winding
the wire round it.  Usually this equipment is at the end of a wiredrawing machine in place of the normal capstan or block.  Wire can then be taken from this non-rotating block



without stopping the rest of the machine, as is necessary when accumulated wire is periodically stripped off a rotating capstan or block fitted to the end of the machine.  The rotating disc or arm has either pulleys or dies which enable the wire to be cast to the fixed block and allow it to be removed in a well cast and "dead" condition.
Dead cast.    A coil of wire is said to be dead cast that when cut it lies in uniform circles. See "Cast of wire."
Deburring.    Removal of rough edges remaining on a workpiece after machining or forming.  Mass produced parts are usually deburred by rotating them with abrasive in a barrel or drum. The process is considerably speeded up in machines with rotating work drums on the periphery of a turret which also rotates in the opposite direction.  Deburring can also be carried out electrolytically in batch plants in barrels or in continuous plants in which the anodic central section is a cylinder around which a helical tract is mounted.
Decibel    Unit to express differences of power level.  Example:  The decibel is 10 times the common
logarithin of the power ratio.  It is used to express power gain in amplifiers or power loss in passive circuits or cables.
Decibel.    A standard logarithmic unit for the ratio of two powers, voltages, or currents.  In fiber optics, the ratio is power.
DB = 10 log 10 ( P1/P 2)
Decibel.    a unit used to express ratios of sound or signal power, defined in such a way that the number of decibels is given by n=10 log 10 P2/P1 where P1 and P2 are power levels. decibels represent a ratio, it is necessary to establish a reference level in order to indicate an absolute level.  For sound, the reference level is a pressure of  0.0002 microbar.
Deflection test.    A test to determine the spring-back of wires as for example copper wire used for production of  enameled wire.  The wire is bent through 90 deg. round a mandrel and when the load is removed the wire is allowed to spring back, the angle of deflection being noted.  Another method is to determine the spring-back by winding a wire several times round a mandrel of given diameter under a given tension. The load is released by cutting the wire which is allowed to spring back slowly.
Deflection.    (a) The sag of a rope in a span.  Usually measured at mid-span as the depth from the chord joining the tops of the two supports. (b) The deformation of a spring on application of
load.
Degreasing plants.    May be of vapor, liquor or multi-liquor type.  The original type of vapor degreasing plant consists of an open tank in the bottom of which the solvent is boiled.  Near the top, around the walls of the tank, is a bank of copper condensing coils through which cold water circulates to prevent to vapor level from rising too high. Such plants must be in a location free from draughts.  Metal parts are immersed into the solvent vapor in baskets or suspended from hooks when it condenses on to them, dissolving the grease and running off into the sump.  As only pure condensate reaches the surface being cleaned there is no possibility of contaminated residues being left on the metal.  The liquor type of plant has two or more compartments,  each containing boiling solvent.  The articles to be cleaned are immersed successively in the various sections, the cleanest solvent being in the last compartment.   Modern degreasing plants are operated automatically, thus eliminating substantially the health hazard of the solvent vapor.
Degree Rise -    The amount of increase in temperature caused by the introduction of electricity into a unit.
Delay Line    A cable made to provide very low velocity of propagation with long electrical delay for transmitted signals.
Denier    A term describing the weight of a yarn (not cotton or spun rayon) which in turn determines its physical size.  The weight in grams of 9000 meters of yearn.
Deoxidized copper.    Obtained by treating molten tough pitch copper (q.v.) with a deoxidizing agent, such as phosphorus.
Derating Factor    A factor used to reduce a current carrying capacity of a wire when used in other
environments from that for which the value was established.
Design Voltage -    Voltage for which a cable is designed.




















Comment:


Dessicant -    Water or moisture absorbent material used to prevent moisture from damaging packaged equipment or other merchandise.
Detector.    An optoelectronic transducer used in fiber optic for converting optical power to electric current.  In fiber optics, usually a photodiode.

Diameter-mismatch loss.

The loss of power at a joint that occurs when the transmitting half has a diameter greater than the diameter of the receiving half.  The loss occurs when coupling light from a source to fiber, from fiber to fiber, or from fiber to detector.

Diamond dies.    Used for drawing the finer wire sizes as described under the entry for die types.

Diamond grinding wheels.

Used for finish grinding bores in sintered carbide dies.  Grain sizes 50 to 70 for rough grinding, 120 to 160 for medium grinding, 200 to 300 for fine grinding, and 320 to 400 for very fine grinding.  Specifications are given in B.S. 2064.

Diamond paste.    Diamond powder ready made up into a paste comprising carrier, wetting agent, and perhaps distinguishing coloring matter.  Not normally used for diamond dies.
Diamond powder.    The hardest abrasive, used extensively in the drilling and polishing of diamond and sintered carbide dies.  Available in various grades, down to 320 mesh in sieve sizes, finer grades by elutriation and other processes, also in pastes.  The most important requirement of a diamond powder is that its particle size should be uniform.  In recent years improved methods of classification have been developed as a result of which powders superior to those classified by the simple gravity sedimentation method have become available.
While a well classified coarse powder does not have its vigor diminished by a mass of "fines" the inclusion of coarse particles in fine powder is likely to cause polishing rings.  A suitable liquid vehicle in which to suspend the powder is olive oil.  The mixture should be
a thin creamy consistency and should, of course, be well stirred before application.  B.S.
1987 specifies sieve and subsieve sizes.  The sieve sizes contain a wide grading and close grading both ranging from sieve size 12 to sieve size 300.  The subsieve range contains 9 groups from 0 to 1 and 40 to 60 micron.  Test sieves are specified in B.S. 410.
Synthetic diamond powder is produced by subjecting carbon to carefully controlled ultra-high temperatures and pressures in an automatic cycle taking about 15 minutes.  The working life and efficiency of this synthetic diamond abrasive can be improved by introducing nitrogen in the quantities that occur naturally in the superior colored natural stones known as "yellow fancies."
Diamond.    Carbon occurs naturally in two crystalline forms, as graphite and as diamond.  The differences in properties between the two is due to the arrangement of the carbon atoms. Diamond is the hardest substance known and its wear resistance is approximately 10 times that of aluminum oxide and 50 to 100 times that of sintered carbide, which explains its
pre-eminence as a material for wire drawing dies.
Dichroic filter.    An optical filter that transmits light selectively according to wavelength.
Die -    A device used in the drawing of the wire; that element through which the wire is drawn, to achieve a predetermined  diameter.  A mold used to form a plastic compound around a wire or cable.
Die maintenance.    Regular maintenance is vital to ensure longest possible life consistent with satisfactory wire.  Taking the die out of service before it has reached the stage where the wire is out of size can avoid undue loss of die material and saves time in opening out, but this has to be weighed against loss of production through too frequent stoppages for die changes.
Bedding-in period. The period in the life of a drawing die when it is first put into service and wear is rapid.  It then settles down to a condition which changes little for a long time.  Eventually the wear seems to intensify and the die quite rapidly becomes unusable.
Cleaning. There are several ways of cleaning dies.  In its simplest form the process is carried out by introducing into the die a solvent for grease such as carbon tetrachloride, trichlorethylene,  benzene, xylol or other solvent by means of sharpened softwood sticks, such as pegwood or doweling of 3 to 6.4 mm. dia. which may be wrapped with cotton wool, placed in the die aperture and rotated with pressure.  This is repeated until the wiper

comes away clean.
Dies can be cleaned ultrasonically by holding individual dies in pliers and immersing them in an ultrasonically activated cleaning field in the tank or by placing a number of dies in a perforated metal tray immersed in the tank.  This process will clean bore diameters as small as 0.064 mm. dia., clogged with diamond powder residues, drill points, metal particles, etc., and takes only five to ten seconds.
Vacuum cleaning is a method by which air is passed through the bore, together with a fluid tat will flush away or dissolve the dirt.  It requires a plant capable of producing an absolute pressure of about 20 cm. Hg.  If the dirt is caked on, and cannot be flushed away, use is made of a sharpened softwood stick with the tip dipped in glycerin; this is placed in the die aperture and the die rotated.

Compressed air alone cannot remove al dirt from a die (unless the air is properly filtered), because of moisture, but its use may be recommended where a piece of wire has broken off and is wedged in the bore.  The wooden stick may be needed for harder metal, but with the end dry in this case.
If these methods fail (or if they are impracticable owing to the small diameter of the
die) the diamond must be removed from its mounting and immersed in a solution that will thoroughly cleanse the bore.  A treatment like this is best carried out by the manufacturer.
Drawing ring.  A ring round the reduction angle of a die corresponding with the line of impact of the entering wire.  This is usually the first sign of wear, and it will become progressively deeper as more wire is drawn through the die.  It is essential therefore to remove the die for repair before the ring becomes deep enough to collect metal powder scraped from the wire.  Failure to remove a die in this condition will result in the packing of the metal powder in the drawing ring to forma chisel-like wedge which will eventually crack the diamond.
Exit chipping.  Sometimes due to faulty but usually to an inadequate radius at corner of exit, or absence of exit cone.
Ovality.  May be fault of die or drawing conditions.  Die fault may mean that entrance and exit parts of profile are "off center", or diamond loose in setting.  Drawing faults include angular setting of die in holder, bad alignment of machine causing wire to enter or leave die obliquely, ovality or unsuitable gauge of wire.
Wear.  See "Drawing ring." There is also wear of a polishing nature in the taper and parallel bearing regions.  Principal factors contributing to die wear are: unsuitable or insufficient lubricant or coolant; foreign matter rolled into the wire, poor pickling practice or insufficient washing; speeds, temperature, and reductions in drawing; die design,  i.e. angles of entry and extent of bearing; variations in quality of die material.
Die Manufacture.    The various process are:
Blending the radii.  all angles in the die profile have to be blended after the actual drilling operation to present a smooth bore.
Drilling.  Process of producing a stepped conical hole in the die material, using special drilling machines with high speed rotating needles provided with diamond powder paste. The width of the die bore is reduced as piercing progresses by reducing the angle of the needle point.  See also paragraphs below on electro-mechanical drilling, piercing by electric arc, and ultrasonic drilling.
Electrolytic drilling.  A great saving of time in the rate of piercing diamond dies is obtained by the use of an electric arc in place of cutting with finely powdered diamond.  A saving of a hundred hours or more has been achieved and, in general, the finer the bore required the greater is the time saved.  It is first necessary to make a conically-shaped incision into the stone by using diamond powder.  The stone is held just beneath the surface of a suitable electrolyte and a pointed platinum alloy needle inserted into the cone. The circuit is completed by a second electrode in the solution and, with suitable electrical controls, arc voltages down to 40 volts can be used.  Holes as small as 0.005 mm. dia.


have been produced in diamond with an electric spark.
Electromechanical drilling. Used for the production of tungsten carbide dies of all shapes; particularly suitable for profiles dies.  All that is necessary is a brass tool of the required cross-section which may have an arbitrary shape and undercuts, shapes hitherto producible in sections and which formed expensive composite dies.  The tool, preferably of brass or tungsten copper, is made the cathode of an electric current, the workpiece is made the anode and the erosive action of the current, necessitating, of course, a careful control, removes the metal.
Laser drilling.  A laser  a narrow and intense beam of light which can be focused to give a very high energy density at the point of focus  can be used to drill diamonds for diamond dies at very high speed.  To avoid fracture and damage the laser has to be applied in brief one-per-second  bursts which vaporize a measured section of the diamond to produce a hole.  The laser is vertically mounted in very compact equipment only a few feet high, a vital part of the equipment being the provision of a continuous clear view of the diamond to enable the operator to control the progress of the operation.  Closed circuit television protects the operator's sight since television cannot transit laser light but only an electrical signal.  To obtain the necessary precisely shaped profile of the bore, laser
drilling must be supplemented by mechanical drilling.
Mounting.  Diamond dies have to be enclosed in a metal socket.  In nonreinforcement mounts the diamond is cast or brazed in the metal holder.  In the reinforced mount, brazing or welding pressure is exerted on to the diamond.  Sintered carbide dies are pressed into steel blanks.
Carbide dies are mounted in a 0.3 to 0.4 percent carbon steel, the larger sizes being
shrunk into the cases after the latter have been heated to about 600 deg. C., while the smaller sizes are cold pressed into the cases.

Piercing.  See paragraphs on drilling, electrolytic drilling, electromechanical  drilling, and ultrasonic drilling.
Polished carbide dies.  Producing a fine smooth finish on the die walls by applying diamond paste on wooden sticks to the rotating die for carbide dies or on special machines for diamond dies.  Dowel sticks of several sizes are used to apply diamond paste to a tungsten carbide die with a reciprocating motion.  Softwood sticks with finer paste are similarly used for final polishing.
Polishing (diamond dies).  Ultrasonic equipment has now superseded the needle type polishing machines.  This equipment is capable of polishing the complete range of diamond die sizes (0.008 mm. to 3.00 mm.) and will remove drawing rings, reshape the complete profile and also increase the bore size and produce a finish far superior than any other in minutes instead of hours.  Final sizing is best achieved by using a high speed wire polishing machine.
Ripping.  A re-grinding operation of sintered carbide dies to re-shape reduction angle and exit angles of dies which have badly worn.
Ultrasonic drilling.  Hard metals and diamonds can be drilled with a hole of any shape using an ultrasonic reciprocating bench drill.  Vibrations are transmitted to a drilling tip which can be example drill a 6.4 mm. square hole 3 mm. deep in tungsten carbide in about
10 minutes, using boron carbide abrasive.  Manufacturers  of this type of equipment claim that entry and exit of tungsten carbide drawing dies can be machined to correct size, after sintering, in 8 to 10 minutes each face.  Since there need not be rotary movement, drilling is not limited to circular or symmetrical holes, but can accommodate intricately shaped holes made only with great difficulty by normal methods.
Die types.    The main types of dies are described in the entries below:
Adjustable dies.  Shaped dies in which sections of tungsten carbide fitted together within a frame form the shaped hole, the size and shape of which is adjusted by inserting a set of spacers of the appropriate size between the sections and the frame, or by adjusting


screws.
Cored dies.  Tungsten carbide die blanks which are prepared with a preformed hole before sintering so reducing drilling time considerably.  The smallest holes preformed are about 0.2 mm.; below this, holes have to be drilled in the solid blank.
Diamond dies.  Industrial diamond with a drilled and polished hole through which wire of steel, non-ferrous metals, tungsten, molybdenum, gold and silver is reduced.  Mainly used for sizes from 0.005 to 1 mm. for the harder wires and up to 2.5 mm. for copper.  The basic requirements in a diamond die are: a good quality diamond; bearing or drawing parallel of exact diameter; a reduction cone of the correct shape for the particular metal to be drawn; an exit relief of correct shape; and a mirror polish over the whole surface. Diamond dies for wire-drawing are specified in B.S. 2946, which deals with quality of the diamond, the mounting, casing size tolerance and marking.  Methods of examining and measuring are given.
Die set.  A combination of wire drawing dies for a certain required reduction
containing a number of dies of stepped diameter, preferably in a geometric series, i.e. with a constant percentage reduction.
Necking dies.  Used for necking shells, capsules, etc.
Preformed dies.  See entry for cored dies in this section.
Profile dies.  Dies having non-circular cross sections, for instance, square, hexagon, etc.  Production of shaped carbide dies is carried out on special machines.
Roller die.  Has two pairs of rollers, a vertical pair with an oval groove to form an oval shape, followed by rolling to a round shape with a horizontal pair.  Advantages claimed include lower power consumption, higher drawing speed, reduction in intermediate annealing and cleaning, improved wire properties and elimination of expensive lubricants. However, they cannot be used for finishing passes as tolerance is usually not better than ±
0.002 in.; set-up time is longer than for ordinary dies and the shape of the oval groove is
critical to ensure that the wire does not turn over and that it will be round after the next rolling.  Experiments have shown that substantial benefits in increased die life can be obtained when drawing copper wire rod to heavy wire by replacing the first two dies by a roller die which gives a 46% reduction of area and maintains a suitable size for considerable periods before regrinding is required.
Ruby dies.  Were in use before diamond dies were introduced and may still be useful for soft metals such as gold and silver.  Their cost is lower than that of diamond dies, but performance may be the same as that of sintered carbide dies.
Sapphire dies.  See previous entry.
Stranding dies.  A pair of steel blocks, which, when put together in a die holder, form a circular or sector shaped hole through which the stranded wires pass to form the finished strand.
Tungsten carbide dies.  Introduced in the 1920's and 1930's and quickly replaced other drawing tools for sizes down to about 0.1 mm., below which size diamond dies are mainly used.  Not so hard as diamond dies and therefore no so long-lasting, but less expensive, more easily shaped and can be made for larger sizes.  The rough die nibs are produced by sintering a mixture of tungsten carbide and cobalt.  For larger sizes the hole is pre-shaped in the sintering operation and finished by drilling and polishing with diamond
or boron carbide abrasive or by spark erosion.  See "Tungsten carbide".
Turks head.  A number of undriven rollers mounted in a frame for rolling shaped wires.  See "Turks head dies" for more detailed description.
Ultrasonically  vibrated dies.  See entry under wire-drawing.
Die.    The tool with a specially shaped hole through which wire is pulled to reduce its diameter.
Manufactured in tungsten carbide for larger sizes or diamond for smaller sizes. Nomenclature for the various parts of a drawing die varies somewhat for the two types of die.  The various parts of a wire-drawing die are as follows:
Approach angle. The second part of a diamond die profile, between the entrance and


the reduction angle with usually a fair tolerance in angle, say ± 5 deg.  Also used as an alternative name for the drawing angle of a tungsten carbide die.
Bearing. Cylindrical portion of the profile which actually controls the size of the wire being drawn.  Also known as the parallel. The length of bearing varies according to the material being drawn and is defined as a percentage of the bore diameter.
Bell. Usual expression for the entrance of a diamond drawing die.
Blank. the pellet (q.v.)
Casing.  Steel casing into which the pellet of a tungsten carbide die is pressed.  Casings for diamond dies may be of steel, bras or alloy.  Usually supplied in standard dimensions.
Drawing angle.  The part of a tungsten carbide die in which the actual reduction of the wire takes place.  In a diamond drawing die the reduction zone and bearing together form the drawing zone.
Entrance.  The first part of the die profile having relatively big tolerances.
Exit zone.  The last part of the die profile on the exit side.
Holder.  Used to maintain the drawing die in its correct position and also to contain the water cooling arrangements for the die.  A traverse die holder is one to which a regular motion is imparted to keep the wire moving on the face of the drawing cones, so preventing grooving.
Insert.  The pellet (q.v.)
Nib.  The pellet (q.v.)
Parallel.  An alternative name for the bearing.
Pellet.  Also known as insert, blank or nib.  The sintered tungsten carbide product from which the die will be manufactured.   The die insert may be solid or it may have a hole or cavity to assist in drilling the hole.
Profile.  The shape worked into the die must be well rounded and polished.  The form of the profile is very important; there are specific forms for different materials.  For details of instruments for measuring the die profile see "Profilometer"  and "Profiloscope".
The die profile can be readily checked by making a plug of silicone rubber.
Reduction zone.  The part of the diamond die profile in which the actual reduction of the wire takes place.  Close tolerance in angle for fine dies is, say, ± 2 deg.  Too large a reduction angle is inadvisable as this increases the redundant work performed during the reduction process, while too small an angle increases the frictional work involved.
Relief.  The part of the die profile following the parallel.  Also known as exit zone or back relief.
Dielectric    An insulating material usually having a very low loss factor (RF Cables). Dielectric -   A material with good electrical insulating characteristics,  insulating medium. Dielectric coatings.    Can be of either polyethylene, polyvinylchloride  or buna rubber, trade names for such
materials being nylon, teflon, kynar, tefzel, etc.  They offer high temperature resistance
with thinner walls and durability and are applied by extrusion to electrical conductors.
Dielectric constant.  The factor by which the electric field strength in a vacuum exceeds that in the dielectric for the same distribution of charge.
Dielectric loss.  Energy dissipated as heat when the dielectric is placed in a varying electric field.
Dielectric strength.  The maximum potential gradient (volts per mil.) a dielectric will withstand without breaking down.
Dielectric Constant    That property (K) of an insulating material which is the ratio of the parallel capacitance (C) of a given configuration of electrodes with the material as the dielectric, to the capacitance of the same electrode configuration with a vacuum as the dielectric.
Dielectric Phase Angle    Angular difference in phase between the sinusoidal alternating potential difference applied to a dielectric and the component of the resulting alternating current.
Dielectric Strength    A term used to describe the limit, without damage of an insulating material, to an applied voltage potential.


Dielectric Strength -    A term used to define the degree of insulating characteristics possessed by a dielectric.
Dielectric.    Any insulating material that is a non-conductor  or electricity.
Diffraction grating.            An array of fine, parallel, equally spaced reflecting or transmitting lines that mutually enhance the effects of diffraction to concentrate the diffracted light in a few directions determined by the spacing of the lines and by the wavelength of the light.
DIN standards    The German Standard Specifications equivalent to the BS series issued by the British Standards Institution, e.g. DIN 1547 for tungsten carbide dies.  Copies of these standards may usually be seen or purchased at the offices of the standards institution in most countries  in the U.K., at the B.S.I. library, 2 Park Street, London, W.1.
Dip forming.    A process for continuous production of copper wire rod in any required length.  A shaved copper rod is passed vertically upwards through a crucible of molten copper, emerging as a much thicker rod which passes up a cooling tower before being led to a rolling mill for reduction to the required size as a continuous process.  Low cost, automatic operation,
continuous strand which can be formed into coils of the largest weights, and a high quality product are claimed.  It is also pointed out that the equipment is lighter, the rolling mill smaller and the plant area smaller, permitting small units to be installed economically at a wire mill.  Capacities can range from 3 to 15 ton/hour.  Since the rod remains in a protective atmosphere until it has cooled to about 50°C., pickling and cleaning are eliminated.
Dip Process -                     The process of covering a surface by means of dipping it into or through a molten bath of the coating material.  This may be followed by dippings or baths in other solutions and/or materials to produce desired results.
Direct Capacitance    The capacitance measured directly from conductor to conductor through a single insulating layer.
Direct Current    An electrical current that flows in one direction only.
Direct Current (DC) -    An electrical current that flows in one direction only.

Direct Current Resistance Direct Current Resistance -

The resistance offered by any circuit to the flow of direct current. The resistance offered by a circuit to the flow of direct current.

Direction of Lay    The direction, either clockwise or counter-clockwise, of a conductor or group of
conductors when looking axially down a cable length.
Direction of Lay -    See Lay Direction
Direction of lay.    The lateral direction, designated as left hand or right-hand, in which the wires of the members or units of a conductor run over the top of the member or conductor as they recede from an observer looking along the axis of the member or conductor.
Disc spool.    A type of reel with large flanges to hold heavy wire in a weaving loom
Disc winding.    A winding consisting of a number of coils each wound singly in the form of a disc and connected by jointing the ends of the coils together.  Chiefly used for high-voltage windings of medium and large transformers.
Dispersion.    A general term for those phenomena that cause a broadening or spreading of light as it propagates through an optical fiber.  The three types are modal, material, and waveguide.
Dissipation Factor          The ratio of the conductance of a capacitor, in which the material is the dielectric, to its susceptence; or the ratio of its parallel reactance to its parallel resistance, or the ratio of the power loss to the circulating KVA.

Distortion-limited operation.

Generally synonymous with bandwidth-limited  operation.

Double block.    A means of obtaining a non-slip accumulation type wire-drawing machine without the use
of overhead take-off pulleys, so avoiding twist in the wire.  A second block is mounted above the drawing block and on the same spindle, but the upper block is free to rotate in either direction.  Wire is transferred from one block to the other via a pulley.  See more detailed description of double block under the entries for wire-drawing machines.  The term double deck block is more properly applied to a bull block designed to produce a


double draft.
Double enameled wire.    The trade term for the grade of enameled wire referred to as "thick covering."
Double galvanized wire.    An alternative name for heavy galvanized wire, used more particularly in the United States.  Also used sometimes to describe wire passed through two spelter baths in succession.  See details for heavy galvanizing in the entry for galvanized wire.
Draft.    The amount of reduction by drawing expressed as a percentage representing the difference in cross-sectional area before and after drawing.
Drain Wire    In a cable an uninsulated wire laid over the component or components and used as a ground connection.
Drain Wires -    A number of small gauge bare wires applied concentrically about the insulation shield of a high voltage cable for the purpose of a fault current return path.
Draw Feed Stock -    Rod or wire that is subsequently drawn to a smaller size.
Draw-Pak.    Equipment by means of which wire can be fed directly into despatch containers of the Pay- off-pak type; with this equipment the containers are rotated.  The Draw-Pak can either be an integral part of a wire-drawing machine, thus providing a continuous wire-drawing and packaging machine, or it can be in the form of a continuous wire packaging attachment for conversion of existing wire drawing machines, processing equipment or coating frames. Various models are available according to the type of process and whether single or multiple wires are to be packed.
Drawbench.    A bench of any length having at one end a die stand and provision for pulling the material through the die straight up the bench by means of a chain.  Usually the chain rotates continuously, a trolley on which is mounted a gripper being maneuvered into the point of the material to be drawn.  When a grip is obtained a hook on this trolley is dropped into one of the links of the moving chain.  A suitable mounted catch releases the jaws of the gripper and unhooks the trolley which is returned to the starting position with a rope.
Later types of bench embody two or more dies, also automatic trolley return and self- releasing grippers.  Push pointing of the material is sometimes used.  Another type of drawbench is arranged with the grippers permanently mounted on the rotating endless chain and they are arranged to grip the point of the material automatically when it is pushed through the die.  The modern draw-benches are equipped with automatic loading and discharging mechanisms saving much time in handling.  Using equipment with remote controls, one operator can produce finished bars or tubes in quantity with minimum effort.
Drawing    In the manufacture of wire, pulling the metal through a die or series of dies for reduction
of diameter to specified size.
Drawing -    The process of reducing a cylindrical rod or wire to a desired diameter by pulling the wire through a die or series of dies thus stretching the wire.
Drawing.    The reduction of metals by the application of stress in tension.  Cold drawing refers therefore to pulling wire at normal temperature through a die in order to reduce the cross- sectional area.  Hot drawing  heating of the wire before entering the die  is employed for tungsten and molybdenum wire.  Deep drawing refers to the drawing of sheet metal into forms involving a great deal of deformation.  See entries under wire drawing , wire drawing machines, die and dies, lubricants, etc.
Drawn flat wire.    A flat product obtained from wire, brought to final dimensions by drawing through a die or by rolling, and furnished in flat straight lengths, in coils, or on spools, reels or drums.
Dressing.       A method of re-casting wire which is springy, due in the majority of cases to the die or die stand being out of alignment with the drum; carried out by running the wire between pegs or pulleys.  Or, to straighten wire being fed to a machine by passing it through a spinner such as that employed in straight length production.
Drop wire.    A term to describe telephone cable usually consisting of one insulated pair used to connect open wire lines on poles to subscribers' premises.
Drossing.    Removal of dross from a galvanizing bath.
Drum twister.    Cable laying-up machines in which both the input core drum carriers and the take-up drum carrier rotate about their own axes.  The rotating caterpillar pulls the cable forward,


producing a controlled lay or twisting action.  To ensure that the relative position of one core to the next remains constant, sensing heads provide impulses to the various carriage motors to either accelerate or decelerate the individual carriages as appropriate.
Drum.    A cylindrical flanged barrel of uniform or tapering diameter on which rope or cable is wound for operation or storage. It may be smooth or grooved. Normally made of cut timbers and assembled with bolts and nails, etc., and usually of flange diameter exceeding
400 mm. Drums of less than 400 mm.  flange diameter are usually called reels. The number of meters of wire rope which a drum will hold can be calculated by the formula:
Capacity =(A+B) AxWxC, when
A    Depth of flange in mm.
B    Diameter of barrel in mm.
W   Width of reel between flanges in mm. d    Rope diameter in mm.
C (Constant) = π/1000d❷
Dry core cable.    Telephone cable insulated with loosely wrapped dry manila paper in ribbon form.
Dual Coaxial Cable    A configuration consisting of two individually insulated conductors laid parallel or twisted and placed within an overall shield and sheath.
Duct    An underground or overhead tube used for carrying electrical conductors.
Dumbell wire.    Two conductors running parallel, the insulation being applied to provide a dumbell shaped cross-section.
Duplex Cable -    A cable composed of two conductors twisted together, usually one insulated and one bare neutral.
Duplex cable.    A two-fiber cable suitable for duplex transmission.
Duplex transmission.    Transmission in both directions, either one direction at a time (half duplex) or both directions simultaneously (full duplex).
Durometer    A measurement used to denote the hardness of a substance (usually of thermosetting and thermoplastic materials).
Duty cycle.    In a digital transmission, the ratio of high levels to low levels.
EC -    Electrical conductor (electrical grade aluminum - now known as Alloy 1350).
Eccentricity    Like concentricity a measure of the center of a conductor's location with respect to the circular cross section of the insulation; expressed as a percentage of center displacement of one circle within the other.
EDFA    Erbium-doped  fiber amplifier.
Edging rolls.    In wire flattening, are placed between the stands of the flattening mill, to shape the edges of the strip and control the width.  The rolls are grooved to form the edge, and may have more than one set of grooves to give a choice of round or square edges.  Smaller mills have idler edging rolls, while the larger mills have edging rolls driven.
Elastic deformation.    A change of dimensions produced by a stress, the deformation disappearing when the stress is removed.
Elastic limit.    The greatest stress which a material is capable of withstanding without permanent deformation remaining on release of the stress.  Also known as limit of proportionality.
Elastomer    Any elastic, rubber like substance such as natural or synthetic rubber.
Elastomer -    Any elastic rubber-like substance, such as natural or synthetic rubber; when stretched to twice its length will resume approximately the original shape.
Electric Gradient    The space rate of change of potential at a point in the direction of the greatest change.
Electrical Length    That length of cable expressed as degrees of a cycle or fraction of a wavelength for the signal transmitted.  The equivalent electrical length of a cable equals the physical length times the square root of the dielectric constant.
Electro Magnetic    Magnetism caused by the flow of an electric current.
Electro Motive Force    That force which determines the flow of electricity; a difference of electric potential.
Electro Positive    A substance which has a tendency to unite electrons in electrolysis leaving it with a

❷


positive charge.
Electro tinned    Electrolytic process of tinning wire using pure tin.
Electro-Tinned  -    Electrolytic process of tinning wire using pure tin.
Electrode    A conductor through which a current enters or leaves an electrolytic cell, arc furnace, vacuum tube, gas discharge tube or other nonmetallic conductor.
Electrode.    One of the conductors carrying electricity into an electrolytic process or piece of equipment.  Also used  in welding (q.v.)  When welding wires, the two electrodes are placed in contact with the materials to be welded and convey the electric current to them to make the weld.
Electrolysis    The production of chemical changes by passage of current through an electrolyte.
Electrolytic copper.    Copper that has been refined by electrolysis.  Crude impure copper is made the anode in a bath containing copper sulphate and is deposited on the pure copper sheets known as starting sheets which act as cathodes.  The refined metal contains upwards of 99.9 percent copper.
Electrolytic Corrosion    Corrosion by means of electrochemical  erosion.

Electrolytic Tough
Pitch

A term describing the method of raw copper preparation to ensure a good physical and electrical grade copper finished product.

Electromagnetic  -    Magnetism caused by the flow of an electric current.

Electromagnetic interference

Any electrical or electromagnetic  energy that causes undesirable response, degradation, or failure in electronic equipment.  Optical fibers neither emit nor receive EMI.

Electromagnetic  testing.    When the armature of an electromagnet is brought near a piece of steel coated with zinc, by measuring the alterations to the electrical characteristics of the magnet, the distance separating the magnet from the steel can easily be measured.  This method of measuring
the thickness of a zinc coat is valuable because it is quick and does not destroy the coating. Electromagnetic  testing is also used to detect faults in cold drawn wire and equipment has been developed for continuous indication of cracks, inclusions, laminations, etc. in hot rolled rod, operating between the last stand and the coiler where the rod is traveling at 5 to
30 m.s.
Electroplate    The term used to indicate the application of a metallic coating on a surface by means of electrolytic action.
Electroplate -    The term used to indicate the application of a metallic coating on a surface by means of an electrolytic action.
Electroplating.    Coating one metal with a thin film of another by placing the article to be plated in a bath and connecting it to the negative pole of a source of low voltage direct current, from a rectifier; the anode or positive electrode is generally made of the metal to be plated, although in some cases an inert anode is used, the metal being supplied by the electrolyte.
Electroplating solutions have been developed to provide deposits having necessary physical properties including bright, surface leveling and high ductility.  To electroplate an article a complex series of treatment stages is required.  This covers pretreatment to
remove soils, grease, oxide films and to give surface activation followed by the
electroplating stage and post plating treatment.  Between each solution treatment stage a water rinse is necessary, small components may be plated in bulk in barrels which are rotated while immersed in the processing solutions.  Larger articles are electroplated by suspending them on racks.  Automatic and semi-automatic  plants are available which employ transfer units for moving the articles to be processed from stage to stage.
Design of the product is important since deposits tend to be thick on protuberances or sharp corners and thin in recesses; blind holes and sea can trap pre-cleaning liquids and cause trouble later.
Elongation.    The extension of a tensile test piece when stressed.  The elongation at fracture is usually expressed as a percentage of the original gauge length.  The elongation of hard-drawn wire varies inversely with the tensile strength  the harder the wire, the lower the elongation value.  Elongation of wires of the same tensile strength varies directly with the cross- sectioned area but inversely with the gauge length, because localized reduction due to


necking has a marked influence on the elongation value.  Elongation of wire also refers to the lengthening of wire during reduction in the die.  Experiments by B.I.S.R.A. have shown that the percentage uniform elongation of wire lightly drafted at each pass is much greater than that of wire heavily drafted at each pass.  Elongation of wire when its diameter is reduced can be calculated from the area reduction as follows: E% = 100 x A.R.% divided by 100  A.R.%.  A 10 percent area reduction therefore gives an elongation of 11.1 percent.
Embossing    A means of marker identification by means of thermal indentation leaving raised lettering
on the sheath material of cable.
EMD    Equilibrium mode distribution.

Emergency Overloads
-

Loads which occur when larger than normal currents are carried through a cable or wire over a certain period of time.

EMF.    Abbreviation for electromotive force.
EMI    Electromagnetic  interference.
Enameled Wire -    A conductor with a baked-on varnish enamel.
Enameled wire.    A conductor with a baked on varnish enamel, may be 3.66 to 0.025 mm.  Intended for use in the windings of motors, coils, transformers, and other applications of a similar nature.
Enameling.    Enameled wires are produced by passing the wire through an enamel trough and then metering the liquid coating so that when it is cured in the baking oven the correct thickness is obtained.  In order to obtain the total coating thickness required by specification and practice a number of coatings must be applied to the wire, and these can be between four and ten, depending on wire size and grade of thickness required.
In the conventional enameling process hard drawn wire passes through a pre-annealer into the enameling oven, then on to the take-up spool.  The temperature in the enameling oven and the throughput speed are determined by the curing rate of the applied enamel, and the annealer temperature is controlled in order to obtain a soft and ductile enameled wire.
More recently, a new process has been in operation, that is enameling in tandem with wire drawing.  In this process a soft copper inlet wire is drawn at enameling speeds, with moderate area reduction, and the resulting wire passes directly  into the enameling process. Enameled wire produced by this process has superior ductility to that made by the conventional method. Elongation is improved, springiness lowered and tensile strength improved.
The enameling process can be carried out both vertically and horizontally and, although at one time only fine wires, i.e. below 0.1 mm., were enameled horizontally, it is now customary to enamel all sizes below 0.25 mm. horizontally and to use vertical operation
for sizes 0.25 mm. and above.  However, this is not a fixed rule and there is some variation on the above.
Oil based enamels.  The oil based enamel used as a covering originally consisted of natural oils modified to the desired characteristics by the addition of natural resins.
The formulations have been continually developed and improved, and this type of
enameled wire continues to be a very useful and economic product for many applications, particularly for those using fine wires.
Although not possessing the greater toughness and abrasion resistance of the more recently developed synthetic enamels, oil based enameled wires may be wound on modern winding machines and give a satisfactory performance in such applications as relay coils, solenoids, field coils and similar uses.  These wires have outstanding resistance to
moisture and may be used for continuous operation at temperatures of up to 105 deg. C
(Class A conditions). The test specification for this type of covering is BS4609.
Polyvinyl acetal enameled wire.  The polyvinyl acetal type of enameled wire is a standard wire covering for many modern applications.  The inherent toughness and flexibility of this type of film makes it a suitable covering for wires to be wound on all types of high speed winding machines.  This type of enameled wire holds a valuable place as a


general purpose winding wire for all applications requiring robust characteristics,  and is rated for continuous use at up to 120 deg. C (Class E) when suitably impregnated.  Typical of these applications are industrial motor windings, transformer windings (including those for oil filled transformers) and relay coils.  These wires are also suitable for hermetic applications and are resistant to the refrigerants in common use.  The test specification for this type of covering is BS4516:Part 1.
Polyurethane coated enameled wires.  The main advantage of a polyurethane type coating is in its ability to "self-flux" on immersion in solder at a temperatures about 350 deg. C. The enamel film breaks down without leaving corrosive residues so that direct connections can be made without prior removal of the enamel film, thus saving time and expense.
These films are tough, flexible and abrasion resistant,  and are suited to modern winding techniques.  They find applications in relay coils, solenoids and small armature windings.  They are of outstanding value in telecommunications, and other electronic equipment where large numbers of soldered joints are necessary.  Rated for continuous operation at 120 deg. C (Class E) they have excellent electrical properties at high frequencies.  The test specification for this type of covering is BS4520.
Polyester-imide  enameled wires.  These coatings based on polyester-imide  resins are tough and abrasion resistant and may be wound on modern winding equipment.  These films have excellent temperature resistance and can be used for windings that are to be operated continuously at temperatures of up to 200 deg. C. (Class H plus operation).  They have outstanding resistance to short term thermal overloads and have high resistance to solvents.
The polyester-imide  enameled wire can be used in all types of applications particularly where high temperature rating is of importance. The excellent solvent resistance makes these coatings suitable for use in hermetic applications.
The test specification for this type of wire is BS4665.
Polyester/amide-imide dual coated enameled wires.  This product has either a modified polyester or polyester-imide  base coat with an amide-imide top coat.  The properties of both films are combined to produce a wire that is hard and tough, and has an excellent solvent resistance along with high thermal stability.
This coating has high resistance to thermal shock and overload and is classed for continuous operation at temperatures up to 200 deg. C (Class H plus).  It is used in such applications as hermetically sealed motors, armatures, field coils and all types of random wound coils, where high temperature operation is required.
The test specification for this type of covering is BS4665.
Bonding wires.  A bonding wire normally consists of a standard synthetic enameled wire overcoated with a thermoplastic material.  The properties of the basic enameled wires are unaffected by the addition of the bonding coat, which permits the use of these wires in self-supporting formless coils.
The bonding may be achieved thermally by passage of an electric current, placing the
coil in an over or by passage of the wire over a hot pulley.  It is also possible to solvent bond these coatings by passing through the solvent just prior to coil forming but care has to be taken on choice of solvent so that the base coat is not affected.
The test specification for these wires is BS4738.
Glass covering.  The glass covering consists of a lapping or braid of alkali free yarn applied to the conductor and subsequently bonded with a varnish.  Glass bonded with a polyester thermosetting varnish is suitable for use under Class F conditions (155 deg. C) or with a silicone varnish for use at Class H (180 deg. C).
Because of the ability of the type of covering to withstand high temperatures, moisture,
and heavy internal condensation,  it is particularly suitable for such applications as the windings of totally enclosed flameproof motors.
Ends    In braiding, a term used to denote the number of wires or threads on a braider carrier.


EPR -    Ethylene Propylene Rubber.

Equilibrium mode distribution.
Erbium-doped  fiber amplifier.

The steady modal state of a multimode fiber in which the relative power distribution among modes is independent of fiber length.
A type of fiber that amplifies 1550-nm optical signals when pumped with a 980- or 1480- nm light source.

ESCON    An IBM channel control system based on fiber optics.
Excess loss    In a fiber-optic coupler, the optical loss from that portion of light that does not emerge from the nominally operational ports of the device.
Exothermic    Characterized by the liberation of heat.
Extensometer.    An instrument for measuring the elongation of a test specimen during the operation of straining.
Extrinsic loss    In a fiber interconnection,  that portion of loss that is not intrinsic to the fiber but is related to imperfect joining, which may be caused by the connector or splice.
Extruder tip.    The guides, sometimes with a diamond insert, used when extruding a plastic or rubber insulation coating on wire with an extrusion machine.  Also known as a core tube or guide tip.
Extrusion -    The application of a semi-solid plastic or rubber material by forcing it on a conduit or wire passing through the extruder in a continuous fashion.
Extrusion finish.    Wire with a smooth lustrous coating suitable for bolt making by the cold head and extruding process.

Extrusion
Thermoplastic/Thermoset

Carried out by extruding the heated plastic over the core material.  Plant for P.V.C. coating of cables, for example, consists of a hopper into which the dice or pellets are dropped, situated over a barrel in which a screw revolves.  The P.V.C. is gravity fed into one end of the barrel, where it softens as a result of local barrel heating and frictional heat. The screw forces the P.V.C. along the barrel and at the same time compresses it in order to expel air and convert the material into a fluid mass.  The extrusion head may be directed at any angle between 45 and 90 deg. to the barrel and provides a continuous flow of coating around the cable (or wire) passing through the head.  The cross-sectional  area of the
groove of the screw is reduced gradually along all or part of its length.  Other variable factors include screw length, diameter and speed of rotation, chosen to suit the material extruded and the rate of extrusion.  It is extremely important that the extrusion temperature is maintained constant at the optimum value for the particular material being processed,
and on many extruders automatic temperature control is provided to cover the necessary processes of initial heating of the barrel to soften the compound, reducing the heating when heat is generated during compression, and if necessary cooling by forced draught or other means.  The quality of the insulation is affected when this is extruded onto a cold conductor; stresses and strains are set up in the extrudate, leading to poor elongation and bending properties and non-adhesion to the conductor.  The most efficient method of preheating the conductor is to pass a heavy current through a small portion of the conductor.
Normally the conductor emerges from the tip of the core with the material stream inside the extruder head at a short distance from the die, and the insulation if formed to the required size and shape as the covered conductor passes through the die.  By the "tubing- on" process, however, using a specially designed core, the insulating material and the conductor are held separate until final forming in the die has taken place.  The tube is then drawn on to the conductor by adjustment of haul-off and extruder speeds.  By this method, any conductor irregularity does not disturb the compound flow and affect the radial thickness, while centring is easily carried out before the conductor is introduced into the machine.
A recent development has been the introduction of vertical extrusion plant with the extruding machines mounted at the top of a tower some 46 m. above ground level, so maintaining  concentricity without difficulty.  It is also an essential part of the process that continuous vulcanization of extruded elastomeric coatings can be carried out immediately


after extrusion without the need for further handling which might cause accidental damage. Immediately after extrusion, the cable passes into an enclosure consisting of a large diameter pipe into which steam is introduced at a pressure of 18 kg./cm❷  and cold water is
held under pressure in the lower half of the tube thus containing the steam in the upper half.  The cold water also cools the cable after it has passed through the high pressure vulcanizing steam.  The cable eventually emerges fully vulcanized into a further cooling trough before being packed on the take-up drum.
Heavy duty power cables insulated or sheathed with the rubber-like elastomers or
cross-linked polythene and ethylene propylene can then be produced in longer lengths and with a smoother surface which removes a source of friction particularly for trailing cables.
Until recently paper has been almost exclusively used for power cables operating at
over 22 kV, but plastic insulation is now also being increasingly used.  P.V.C. for voltages up to 33 kV and polythene for higher voltages.  Polythene insulation both in solid form
and with some type of air spacing is now widely used in co-axial cables and P.V.C. and polythene are increasingly accepted for the insulation of the conductors of various types of telephone cables, house wiring cables, weatherproof cables, etc.
Extrusion.    (1) The flow of metal under compression, when it is forced through a dies, as opposed to pulling it through as in wire-drawing.   Extrusion is used in cold forging to reduce the wire by forcing it through a conically formed extrusion ring, contained within specially designed heading dies in a transfer or reheader.  See "Cold heading".  The extrusion process is also used for the manufacture of nonferrous wire rod, particularly in qualities which are difficult to roll.
(2) The provision of a continuous coating of plastic or rubber around a cable or wire as it passes through a die in the head of an extruder.
In one form of hydrostatic extrusion, a high pressure chamber contains both the material for reduction and a fluid which is pressurized by a plunger operated by the press ram or by other means.  The pressure of the fluid forces the material through the die without contact between ram and material.  Because the fluid is an efficient lubricant, conical entry dies with a very small included angle can be used; this together with reduced friction results in a lowering of the extrusion pressures by as much as 40 percent.  The process therefore appears suitable for manufacture of very fine wire as well as rod, tube, billet, etc. particularly in difficult materials.
F -    Fahrenheit.
Factor of Assurance -    The ratio of the voltage at which wire or cable insulation is tested to that at which it is used.
Fall time    The time required for the trailing edge of a pulse to fall from 90% to 10% of its amplitude; the time required for a component to produce such a result.  "Turn off time."  Sometimes measured between the 80% and 20% points.
Farad    A unit of electric capacity.
Farad.    A unit of capacitance.  Usually expressed in microfarads (µF) one millionth of a farad, or picofarads (pF) one millionth of a microfarad.
Fasteners.    A generic term used to describe bolts, screws, nuts, rivets, clips, etc. made from wire of strip.
Fatigue Resistance -    Resistance to metal crystalization that occurs when the conductors or wires break from flexing.
Fatigue.    The tendency to fracture by means of a progressive crack under repeated alternating or cyclic stresses considerably below the tensile strength.
Fatigue failure.  A condition brought about by a fracture caused by the propagation of a crack at a surface discontinuity which has concentrated stress to a value exceeding the safe limit.  "See Fractures".
Fatigue limit.  One half of the maximum range of stress, when the mean value is zero,


which the material will withstand for a specified large number of applications.
Fatigue range.  The maximum range of stress, which the material will withstand for a specified large number of applications.  When the mean value is zero the fatigue range is twice the fatigue limit.  The fatigue range is determined by the fatigue test.
FCC -    Control Cable - Flexible
FDDI    Fiber Distributed Data Interface.
FEP or FEPB -    Fluorinated ethylene propylene insulated, 90 degrees C dry location, 200 degrees C dry location special application.
Rubber insulated fixture wire 60 degrees C, 300V.
FF -
Fiber Channel.    An industry-standard  specification for computer channel communications  over fiber optics and offering transmission speeds from 132 Mbaud to 1062 Mbaud and transmission distances from 1 to 10 km.

Fiber Distributed Data Interface network. Fiber-Optic Interrepeater Link.

A token-passing ring network designed specifically for fiber optics and featuring dual counterrotating  rings and 100 Mbps operation.
A standard defining a fiber-optic link between two repeaters in an IEEE 802.3 network.

Fibrous Filler    A material used to fill interstices in cables made from fibers such as cotton, glass, etc.
Field Wire    A term defining a light, small, wire type usually produced in long lengths for use in communications  in the field.
Figure eight wire.    P.V.C. insulated wire which has a cross section in the shape of a figure eight, since it consists of two conductors lying parallel which can be easily separated for making electrical connections.
Filler    (a) A material used in the cable to fill large interstices between electrical components. (B) A substance, often inert, added to a compound to improve properties and/or decrease cost.
Filler -    See cable filler.
Film    Another term to describe thin plastic sheeting.
Fin.    A protruding rib of metal running longitudinally along a rolled product, such as results from overfilling rolling pass.
Fines.    Product passing through a screen or sieve, as opposed to shorts which remain on the screen or sieve.
Finishing die.    The last die on a wire drawing machine, usually mounted in a special holder sot hat it may be set at any suitable angle relative to the wire line, to ensure perfect cast of the finished wire.  For certain wires a rotating finishing die is an asset, ensuring even wear on the die.
Flat cable.    Another name for contour cable (q.v)  In the U.K. a flat cable has two or more insulated cores or multicores laid side by side and running parallel to one another and which may or may not be sheathed overall in a flat configuration.
Flat Conductor    A wire manufactured in a flattened form as opposed to round, or square, conductors.
Flattened wire.    Round wire which has been flattened by passing through rolls.  Close thickness tolerance is easily maintained, but if width tolerance is important or the edges are to be other than rounded, edge rolling units must also be used and an adequate prestraightening  unit is necessary to ensure a correct straight entry of the wire into the rolling unit.
The initial diameter necessary to obtain particular flat size can be roughly determined by adding the width and thickness of the flat and dividing by two.  The range of sizes produced by wire flattening extends from 16 mm width and 4 mm thickness down to
0.025mm thick by approximately 0.1 mm wide.  Applications range from steel tape,
transformer strip, zip fasteners and resistance elements to such precision products as hair springs and electronic tube components.
The advantage of flat wire over slit strip and drawn strip lies in closer thickness and width tolerances, better edge, smoother surface and availability of traverse wound and tape coils.  Strips with width/thickness  ratios of 5:1 and below are more economically produced by wire flattening than by drawing.  It is now also claimed that for strips having ratios of
5:1 to 10:1 which were slit from wide strip and also drawn, where a radius on corners or


semi-circular edges are required, wire flattening again makes the production more economical.
A large roll will give more spread than a small roll because a larger area of the large roll is in contact with the material  Rolls with a rough surface give more spread while smooth rolls give more elongation, since it is the friction which causes the spread.  A thick lubricant can tend to give more spread with some materials though this depends on the hardness of the material and the reduction.  Variations in the back tension necessary for even feed during rolling and the pull needed to ensure even removal from the rolls can
both alter the rolled size.
Flattening mill.    The basic design of modern flattening mills consists of a two to four stand tandem mil usually equipped with edging rolls.   Single stands are also available for special work.  The first stand of a tandem mill carriers out the actual flattening, while the following stands reduce the strip in thickness and increase the spread further according to roll diameter.  A continuous thickness and width gauge is usually fitted between the last stand and the
coiler, and gives visual or audible warning or stops the mill if a given tolerance is exceeded.  Traversing coilers are generally used to prevent kinks in the flattened wire.
Flattening.    The first operation for diamond drawing dies carried out on a scaife (q.v.). The diamond is usually held in a mechanical clamp.
Fleet angle.    The angle between position of a rope at the extreme end wrap on a drum, and a line drawn perpendicular to the axis of the drum through the center of the nearest fixed sheave.
Flex Life    Ability of a conductor, wire or cable to withstand repeated bending.
Flexible cable.    A cable containing one or more cores, each formed of a group of Wires, the diameters of the cores and of the wires being sufficiently small to give flexibility.
Flexible shafts.    Method of production varies, but usual method is to wrap the wires closely and to correct pitch around a center wire.  Further layers of wire are similarly wrapped to build up the required diameter of the shaft. The successive layers are wrapped in alternate directions, so that the resulting criss-cross construction enables the shaft to bend in any direction. Used in the manufacture of flexible shafts for speedometer and other indicating instruments, for portable grinders and remote control shafts, etc.  Flexible shaft wire is a low carbon, medium high carbon or high carbon wire, either bright, galvanized or coppered finish, in the approximate size range 0.01 to 2.6 mm. dia.
Flexion test.    An alternative name, used mainly on the Continent, for the bend test (q.v.) in which a wire test piece is held at one end and bent at right angles over a former to test its ductility.
Fluid lubrication.    Use of a continuous fluid film during wire drawing to prevent metal to metal contact.  See details of hydro-dynamic  lubrication under the entry for lubricants.
Fluidized bed.    Solid particles in a container rest on a fine mesh screen and when air under constant pressure is fed into a diffusing chamber below the screen, the air passes up through the particles and the bed becomes fluidized.  Recent commercial developments have resulted in gas fired, high temperature fluidized bed furnaces designed to replace lead baths for the
continuous annealing or patenting of wire and strip.  Such furnaces can process 25 wires of
3.2 mm. dia. at 0.46 m. per sec. or 50 wires of 1.6 mm. dia. at 0.85 m. per sec.
Flux    (a) A material that helps produce fusion, as solder flux. (b) A continuous flowing or passing, as in the field created by a magnet.
FM    Frequency modulation.
Foaming agents.    Added to pickling baths to produce a foam blanket which reduces acid fumes.
FOIRL.    Fiber-optic interrepeater link.
Fork lift truck.    A truck with a vertical framework on the front by means of which two flat prongs, which have been forced beneath the load, can be raised off the floor with the load for transportation and also raised higher if required to place the load on a stack or on storage staging.  So far as the wire industry is concerned, the term is usually used to refer to a fork lift truck on which a boom attachment has been substituted for the fork.  This pole, which projects horizontally forwards, can be raised or lowered while remaining horizontal. although necessitating provision of clear gangways for truck traffic, this means of moving


coils of wire rod or wire is fully flexible since handling capacity is easily diverted to meet changing requirements and to ensure best use of storage space.
FPM -    Feet per minute
Fractures.    A large number of different descriptions can be applied to fractures occurring during processing or testing.  Some of the commoner types include the following:
A columnar fracture has angular, fingerlike projections.
A conchoidal fracture is either convex or concave resembling a shell.
All fractures are crystalline, but the term crystalline fracture is generally applied only to those fractures characterized by a lack of visible plastic deformation.
A cup and cone fracture which gives a pointed cup on one broken piece and a cone- like shape in the other.
A fatigue fracture presents a smooth surface and frequently shows concentric markings with the nucleus, at which there is an abnormal concentration of stress, as center.  Also known as progressive or detail fractures.
A fibrous fracture is of a long stringy nature, usually denoting a tough and ductile material.
A granular fracture has a rough surface, similar to sandstone.
A ragged fracture has no regularity and pieces frequently break away from it.  Also known as Broken Stick Fracture.
A shear fracture is a straight plane fracture at an angle of about 45 deg. to the axis of the specimen.  Also known as angular fracture.
A silky fracture is a smooth grey fracture of very fine grain giving a lustrous appearance reminiscent of silk.  Usually a characteristic of tough, strong metals.
A star fracture presents a broken surface resembling a star or rosette and usually denotes a sorbitic steel.  Also known as a rosette fracture.
In a woody fracture, slag particles cause an appearance similar to wood.
Fraying    In cabling, a term used to describe the unraveling of a fibrous braid.
Frequency modulation.     A method of transmission in which the carrier frequency varies in accordance with the signal.
Frequency.    The number of times an alternating current repeats its cycle in one second.
Fresnel reflection loss.    Loss of optical power due to Fresnel reflections.
Fresnel reflection.    The reflection that occurs at the planar junction of two material having different refractive indices; Fresnel reflection is not a function of the angle of incidence.
Fume extraction.    Necessary in the pickling shop to give proper working conditions and to prevent structural corrosion.  Important to arrange exhaust hoods and trunking so that they do not interfere with operating of lifting gear over tank.  In a lip type fume extractor, the fumes are extracted by trunking resting on the sides or lip of the bath or baths, thus not interfering with the entry or removal of the work from the bath.  In another method sufficient clean air is withdrawn by a fan placed above and to one side of the tank, to form an invisible barrier of clean air; the fume laden air cannot pass this barrier and so it too is carried away by the exhaust fan.  Hot air is also blown across the surface of the acid bath from one side opposite the extraction.  This removes practically all fumes.
A third method consists of completely enclosing the cleaning line in what is virtually a building within the main building, using light material impervious to corrosive action of fumes, and arranging ducting and fans to carry the fumes completely out of the main building.  Though initial cost are high, considerable savings on maintenance charges for the building make this method well worth considering for continuous strand cleaning.
Furnace atmosphere.    A gas introduced into a furnace to preserve the bright surface of the wire or prevent the development of undesirable properties in the wire.  Normally it is a controlled atmosphere whose composition and distribution are deliberately controlled to achieve the desired
effect on the material being processed.  The subject is dealt with in more detail in the entry for protective atmosphere.
Furnace purging.    Removing all air and other undesirable gases from a furnace before introducing a different

atmosphere.  For instance, when using cracked ammonia or hydrogen in batch type furnaces, prepurging with an inert gas such as cylinder nitrogen is essential.  If this precaution is omitted, sooner or later an explosion will occur.
Furnaces.    A wide range of furnaces, heated by electricity or gas, are used for the heat treatment of wire either to soften it to enable it to be drawn satisfactorily, or to impart desired properties required in the finished wire.  Brief details of some of the commoner types are given below.
Batch Type. A furnace in which one complete batch of material is placed in the furnace, treated and removed before the next batch is treated.
Bell Type. A batch type bright annealing furnace consisting of a movable bell furnace heated by electricity or gas and a number of fixed bases or hearths on to which the chargé is loaded either directly in charge carriers or on spiders, and covered with a protective hood before the bell is placed over them.  After annealing is finished, the bell is removed and a cooling hood is placed over the inner protective hood.  Under the cooling hood are coolers which blow cold air against the inner hood, reducing the cooling time by up to 50 percent.
Continuous.  One in which the process is continuous by means of a conveyor or by passing individual strands of wire through a fixed furnace.  See "Strand Type" in this furnace section.
Conveyor.  One in which the charge is carried through on a continuous heat resisting mesh or chain belt.
Forced Air Circulation.  Incorporates a centrifugal fan which forces air over the
heating elements and round the work in the furnace, so ensuring uniformity of temperature.
Hairpin type.  An electric furnace for annealing and patenting so named from the shape of the heating elements.  The furnace consists of along chamber through which pass four
12.7 mm. tubes of heat-resisting alloy, the heating elements being fitted to the top and bottom and of the tubes.
Hood type.  See "Bell Type" in this furnace section.
Induction.  An electric furnace in which the electric current is induced within the metal charge by coils carrying alternating current.
Mobile annealing.  A furnace which is mounted on wheels to travel along rails to any one of a number of working positions, arranged so that it can be moved by one operator.
Muffle.  One in which the charge is contained in a refractory container called a muffle, which is heated from the outside.
Pan conveyor.  Used for hardening of small parts which are loaded on to a pan which is then placed in the appropriate position on the entry plate where lugs on the pans engage with the sprockets on the chains of the conveyor taking them through the heating zone of the furnace.
Patenting furnace.  See "Patenting".
Pit type.  a stationary bright annealing furnace located in a pit, from which the atmosphere-tight  container with its charge can be removed and placed in a cooling pit which has room for a number of containers.  If a preheating chamber is incorporated so that charged pots awaiting annealing are heated up to about 400 deg. by means of the waste gases from the annealing chamber, annealing time and fuel consumption are greatly reduced.
Pull-through type.  See "Strand type" in this section.
Pusher type.  A furnace in which wire coils are loaded on trays equipped with their own rollers which run on fixed rails in the furnace when the charge is pushed through. Permanently installed moving parts, such as are found in a roller hearth furnace, are eliminated.
Radiant tube.  A gas furnace in which the products of combustion do not enter the furnace, but are circulated through tubular elements from which the heat is transmitted to the charge by radiation.


Roller hearth.  One in which the charge is moved over driven rollers, sometimes water- cooled.
Rotary hearth.  One which is annular in plan, moving round continuously or intermittently, conveying its charge from the charging to the discharging doors.
Salt bath.  Used for annealing and patenting, as a substitute for lead patenting and for descaling.  Operating costs appear high, but the salt bath provides fast, scale-free production without decarburisation  of the product.  Heating is carried out by means of three carbon electrodes projecting into the bottom of the annealing vessel; through the resultant pinch effect, the solution is continuously moving and the temperature throughout the bath is uniform.
Shaft furnace.  Another name for a pit furnace.
Shaker hearth.  A furnace for small parts which are placed on a grooved or plain plate which is agitated at predetermined  intervals, causing the charge to move through the heating zone at a controlled speed.
Strand type.  A continuous furnace in which wires are run straight from bobbins or swifts through the heating and cooling chambers, tension being maintained by the winding frames situated adjacent to the exit end of the cooling chamber.  For annealing, it is necessary for each wire to run through a small bore tube into which the protective atmosphere is introduced.  While in an ordinary furnace, with up to 20 wires pulled through side by side, there is the likelihood they may become tangled if the wire does not run true, in a tube furnace each wire is segregated in an individual tube and they cannot
touch each other.  However,  a tube-furnace is not so easily brought to an even temperature for each wire.  In patenting furnaces, this difficulty can be overcome by combining a charging end of the tube type and a discharging end without tubes but shorter so that there is no danger of the wires becoming entangled.
Top hat.  See " Bell Type" in this furnace section.

Fused coupler.                   A method of making a multimode or single-mode coupler by wrapping fibers together, heating them, and pulling them to form a central unified mass so that light on any input fiber is coupled to all output fibers.
Gage    A term used to denote the physical size of a wire.

Galvanized wire, finishing of.

If galvanized wire is drawn on a non-slip machine with dry soap and lime, and if this is left on the wire it will cause staining.  This can be avoided, and a highly polished clean finish provided, but wet-drawing the last hole with a suitable drawing compound arranged with a wet box with water-cooled dies and a circulating pump.  This removed the soap coating. The polished finish demanded for such purposes as corset, stitching and mattress wire, where a smoother finish is required than can be obtained by wiped galvanizing, can also be produced by wet drawing after passing the wire through a dry soap box before entering the machine.  The base size depends on the desired tensile strength in the finished drawn wire, and this usually requires about 80 percent reduction of area.  The wet lubricant, such as soluble oil, should be quite weak.  If it is too strong, the wire is liable to "suck down"  a condition peculiar to galvanized wire, in which the diameter of the wire in places becomes less than that of the drawing die.  For this reason it is advisable not to exceed a solution strength of about 10 percent.  In cold weather the lubricant should be warmed before starting in order to dissolve the fats, while when in production cooling is necessary to prevent it breaking down.  To avoid weakening the lubricant, any steam for warming or water for cooling should be passed through the lubricant in a closed circuit.
When drawing galvanized wire one hole, the following solution is said to impart a polished finish:  0.45 kg. of soap powder, 0.47 lit. of good lubricating oil and 13.5 lit. of water.  This mixture should be boiled for 15 minutes and allowed to cool before using.
In America, wiped galvanized wire is often run through a short bath containing a water- soluble wax before winding.  The resulting thin coating of wax has the dual purpose of preventing white rust and giving some degree of lubrication during subsequent fabrication


of the wire into such products as netting, barbed wire, etc.
Galvanized wire.                    Wire to which a coating of zinc has been applied as a protection against corrosion.  This can be carried out either by dipping in a bath of molten zinc, or by electro-deposition  of the zinc coat from an aqueous solution of a zinc salt.
The testing and properties of galvanized zinc coatings on steel wires are specified in B.S. 443, which gives the weight of coat for the full range of wire sizes and lays down accurate methods of testing.  A further testing method is the simple volumetric method in which a measured length of wire is dropped into dilute acid contained in a special type of glass burette and the weight of coating estimated from the volume of hydrogen evolved and measured in the apparatus.
Peeling of the galvanizing coat may be due to several factors including a galvanizing bath at too low a temperature or insufficient chilling of the material on leaving the zinc bath, when using the hot galvanizing method.
Hot dip galvanizing.  wire is hot dip galvanized by passing a number of wire strands through a bath of molten zinc in a continuous process, as opposed to wire work and larger articles which are invariably dipped by being lowered into the bath and excess zinc removed by placing the articles in an air blast cabinet before the zinc has actually set.
In a typical plant for wire galvanizing, the wire is run from the pay-off reel through a
pickling bath, then into a cleaning bath and if necessary a flux tank; it is then led into the zinc bath at the exit end of which there is a wiping arrangement; finally it is coiled again. In many cases an anneal is incorporated in the galvanizing process by introducing a continuous annealing furnace between the pay-off reel and the pickling bath.  In recent lines a lead bath is placed before the galvanizing line through which hard drawn wire is passed, so that it emerges in an annealed condition with a surface that is easily prepared
for galvanizing.  On emerging from the galvanizing bath, the wire may be close wiped and subsequently water quenched,, wiped galvanized, or wiped by oiled charcoal grains to give a heavy coating of zinc (heavy galvanizing).  Higher coat weights are obtained by running faster and thereby dragging out more zinc.
A two-way diffusion process takes place between the iron and the zinc and several iron-zinc alloy layers are formed, consisting of three main alloys.  Although the iron-zinc layers are necessary to bond the metals together the alloy should not be too thick otherwise the coating will tend to flake when the wire is bent, and the torsion properties will also suffer.  Rimmed mild steel needs to pass through a cyanide bath in which the surface molecules on the wire become carburized and allow diffusion to take place in the zinc
bath, otherwise it is most difficult to get a satisfactory coating.  Steels which have been killed (containing approximately 0.2 percent silicon) tend to form a thick alloy layer.
Tensile strength of steel wire is decreased and percentage elongation increased as a
result of the tempering effect of the zinc bath temperature.  The number of torsion's and bends the wire withstand is reduced after hot dip galvanizing because of the brittle zinc- iron alloy layer formed between the base metal and the coating.
Electro-Galvanizing.   Electro-deposition  of the zinc coat on wires passing through an aqueous solution of a zinc salt in a continuous process.  Unlike hot galvanizing where a surface alloy is formed between the wire and the zinc to give adhesion, electro-galvanizing depends on mechanical adhesion, so that the provision of a clean and grease-free metal surface before galvanizing is of the utmost importance.  Acid electrolytes are always used, and deposition may be with insoluble anodes or with soluble anodes of pure zinc.  Using zinc anodes, the main constituent of the electrolyte is zinc sulphate; apart from that, additions of alkalisalts increase the conductivity, and additions of aluminum and mercury salts improve the smoothness of the deposit and the anode solubility.  After the wire leaves the galvanizing bath it enters a hot wash bath to remove the remainder of the acid.  It is then polished.
Advantages claimed when compared with hot dipping include:  pure zinc coating even if original metal is impure; less likelihood of flaking on bending; very even and exact


coating possible where needed; physical properties of the wire not affected because it is a cold process.  The weight of coat is controlled by increasing or decreasing speed and is easier to control than in the hot dip process.  Pitting can however occur often as a result of trace elements such as antimony or cobalt in the electrolyte or as a result of acid attack at the exit end of the cell by sulphuric acid formed when the zinc sulphate decomposes as zinc is plated on the wire.
The thinness and uniformity which can be achieved with electroplated zinc coatings makes them particularly suited for treatment of screws and other threaded parts, since the plating does not seriously affect thread diameters.  The deposit is very much thinner than those applied by hot dip galvanizing and correspondingly  less durable.  The deposit is very much thinner than those applied by hot dip galvanizing and correspondingly  less durable. The deposit is generally applied from a cyanide solution which has a very high throwing power, so that a good coating is obtained in recesses.  Automatic machines have been constructed for the bulk treatment of nuts, bolts and screws on a large scale in barrels.
Cold galvanizing.  As an alternative to hot dipped or zinc spray galvanizing wirework can be coated by painting on a zinc rich paint containing between 90 and 98 percent zinc dust, carried in a suitable binder and diluted with a solvent to a consistency that permits of easy application.
Dry galvanizing.  Galvanizing in which prefluxing is used; the salts on the surface of the work themselves function as the flux.  Since there is no flux layer on the surface of the bath as in wet galvanizing, the surface area is kept as low as possible to avoid oxidization.
Flake galvanizing.  A process for galvanizing nails which consists essentially of melting granulated zinc in contact with the nails in a heated rotating drum.
Flame seal galvanizing.  A process in which the weight of the zinc coat on wires emerging from the molten zinc bath is regulated by a special mechanical device, and in which the still unsolidified coat is passed through a controlled flames, with the object of evening out the distribution of zinc on the wire.  Wires thus treated have a matte surface.
Fully galvanized.  Drawn to finished size and galvanized.  Also used to denote heavy galvanizing (see below) particularly in America; heavily coated galvanized wire is also known as double galvanized, extra galvanized or charcoal wiped.
Galvannealing  process.  A galvanizing process in which the wire with still unsolidified spelter coat and without contacting the surrounding atmosphere is passed through a controlled atmosphere furnace at about 650 deg. C.  immediately on leaving the molten zinc bath with the object of converting the coating entirely to iron-zinc alloys.
Heavy galvanizing.  Covering wire with a heavy coat of zinc as opposed to wiped galvanizing; both types are in fact wiped, the heavily galvanized wire with oil and charcoal.  To give even coatings with a maximum flexibility the wire travels vertically from the charcoal wiper to a set of creel pulleys above the bath.  This allow time for the molten coating to solidify.
The creel pulleys are often set 6 m. or even more above the bath or alternatively the coated wires can be water quenched some 1.5m. above the bath by passing them through water jets; an air blast below the jets will prevent water flowing down on the wire surface
into the charcoal bed.  Coating weights of 225 to 450 gm/m❷  depending on wire diameter,
speed, and length of immersion in the spelter pot, have been achieved by this method. Using a charcoal mixture with additions of cylinder oil and granular zinc chloride, a 114 to
127 mm. bed of charcoal has been found most suitable.
Sand galvanizing.  Galvanizing in which the wire, after passing through the zinc bath, is conducted through a pad of damp sand which scours the wire and removes superfluous zinc.
Sendzimir process.  A galvanizing process which entails the controlled surface oxidation of the material, followed by reduction of the thin oxide layer in a high hydrogen

❷


atmosphere which is maintained right until immersion in the molten zinc bath,  thus eliminating both pickling and fluxing.  Widely used over many years for strip galvanizing, has also been developed for wire galvanizing.  The as-drawn wire is cleaned electrolytically,  mechanically or ultrasonically  in the first method by passing it through successive anodic and cathodic baths containing a solution of sodium salts.  After passing through a water rinse tank the wires pass into an oxidizing furnace similar to a normal patenting furnace, each wire being in its individual tube, and a small volume of air being blown through the tubes to ensure a regular oxide layer.  The wires with their thin coating of oxide travel through open air before entering an identical reducing furnace.  The furnace tubes are extended at the exit end by similar bore tubing of stainless steel to act as cooling tubes which can be air cooled or packed with insulating material to retard cooling as necessary to ensure that the wire enters the zinc at the galvanizing temperature in all
cases.  Advantages claimed include instant wetting and adhesion with reduced thickness of
brittle iron/zinc layer, wires can be produced with varying degrees of hardness, all types of steel can be handled, elimination of fluxing and pickling, smaller zinc bath and lower
costs.
Wet galvanizing.  An older method of galvanizing which a flux layer floating on the surface of the zinc in the bath removes excess moisture, cleans the surface of the work from oxide and helps molten zinc to wet it.
Wiped galvanizing.  Covering wire with a thin coat of zinc.  The wires leave the galvanizing bath at a comparatively shallow angle and run through wipers such as combs, asbestos reels, tin, cork or asbestos presses, vulcanized rubber, etc. immediately on emerging from the bath; by these means, the coating of zinc is much reduced.  Wiped galvanizing is usually employed for wires which have to be further reduced after galvanizing.  The term wiped galvanized is also used for electrogalvanized  wire of an equivalent coating.
Three different types of finishes can be obtained  dull, satin and silver-bright.  Dull finished wire is obtained by passing the wire direct from the asbestos wipes to the take-up frame, so permitting the wire, while in transit, to oxidize because of its own heat.  A water quench 2.5 to 3 m. from the asbestos wipes, stops the dulling or oxidizing of the wire at a given point in its travel to give satin-finished wire.  Silver-bright wire is obtained only if the water quench is within 150 mm. of the wipe; this quench should only set the zinc, so that the wire does not leave this operation cold.  Bright galvanizing can also be obtained by passing the wire through a polishing die similar to a wire drawing die immediately before re-coiling.
Wire cloth galvanizing.   Carried out by means of a bath with a roller arranged so that the wire cloth passes under it and comes up nearly vertical to promote an even coating.  To help reduce the amount of zinc picked up it is usual for the wire cloth to come out through
a layer of sand or charcoal which helps to wipe the molten zinc off the joints in the cloth. The roller may be made of mild steel and will need to be cleaned at intervals to remove the zinc iron alloy which builds up on its surface.  It is usual to arrange for the front of each
roll to be attached to the end of the previous one so that the cloth goes through the galvanizing machines continuously.

Galvanizing -    A coating of some metal part (usually steel or iron) with zinc by dipping or electroplating.
Galvanizing bath.    Essentially a tank containing the electrolyte and zinc anodes for electro-galvanizing, but in hot dip galvanizing provision has to be made for heating, while the bath has to be a very much stronger structure to withstand the weight of the zinc and to take account of the fact that zinc is a relatively bad heat conductor.
When galvanizing by the hot process, the life of a galvanizing bath is dependent on the observance of two conditions: the temperature of the bath should not exceed 480 deg. C., and the silicon content of the bath steel should not exceed 0.07 percent.  A suitable steel composition is given as carbon 0.10-0.15 percent, manganese 0.45-0.60 per cent, sulphur


0.05 percent maximum and silicon 0.07 percent maximum.  Steel complying with this specification is known as fire-box steel and is generally used by galvanizers in Great Britain.  An American specification gives slightly lower carbon and manganese contents. Whatever the composition of steel used, it is most important to avoid hot-spots.  Care must also be taken at welds to see that enough filler metal is present to maintain the effective wall thickness and that the filler, too, has a low silicon content.  Pots should be heat- treated to relieve stresses before they are installed.  It must be remembered that zinc is a relatively bad heat conductor, although it has a high heat capacity when molten, so that the heat of the bath evens out only very slowly.  Ceramic baths are also used, in some cases with over-firing on the top surface of the zinc beneath a cover.
Gap loss.    Loss resulting from the end separation of two axially aligned fibers.
Gauge -    A term used to denote the physical size of a wire.  See American Wire Gauge.
Generator -    A machine used to change mechanical energy into electrical energy.
Giga    A numerical prefix denoting one billion as a gigacycle is one billion cycles.
GIGA-Hertz -    One billion hertz (109HZ) equal to 1 KMC (1000 megacycles).


Gigahertz.    A term for 10❾ cycles per second.  Used to replace the more cumbersome term kilomegacycle.   GHz.
Glass Braid -    Used to provide thermal and/or mechanical protection to the underlying insulation of certain types of conductors.
Glass fiber    Used as an insulation for wire in cloth or tape form or in continuous fine lengths.  Has high tensile strength, high resistance to extreme heat and is unaffected by acids (except hydrofluoric), oils and corrosive vapors.  Fiberglass is a registered trade name for a material of this type.
An inner layer of staple glass fiber silver is useful for a cushioning effect between the ordinary continuous glass fiber yarn and the conductor.  The outer layer is of continuos yarn.
A covered aircraft cable might be made up of the conductor, an extruded covering of synthetic resin and a braid of continuous glass fiber yarn, impregnated with varnish.  The synthetic resin covering could be replaced by a thin tape wrapping of synthetic resin covered with a glass fiber braided sleeving impregnated with varnish.  A 600-volt control cable for boiler rooms, kiln rooms and steel mills is a good example f the use of Fiberglass insulation to overcome severe conditions on operation such as high temperature or moisture. The stranded conductor is covered by two layers of heavily impregnated glass fiber silver insulation, tow or more layers of varnished fabric, a braid of continuous Fiberglass yarn, a lightly impregnated glass fiber staple filler, a moisture-proofed  glass fiber tape and a heavily impregnated Fiberglass braid, giving excellent resistance to acid, oil and corrosive vapor attacks.
Fiberglass insulation is also used for the sever condition met with in cables buried direct in the ground.  The minimum of maintenance is required, as the expense of digging it up is low.  This depends largely on its being light of weight and small in outside diameter, in proportion to the reliability and durability demanded of it.
Graded-index fiber.    An optical fiber whose core has a nonuniform index of refraction.  The core is composed of concentric rings of glass whose refractive indices decrease from the center axis.  The purpose is to reduce modal dispersion and thereby increase fiber bandwidth.
Granulator.    A machine which cuts extruded plastic into granules for re-use.  Recent machines accept hot waste direct from the extruder head without prior cooling and incorporate an air extraction system which conveys the granules back to the extruder hopper or to a bagging point.
Gravity block.    An inverted capstan which allow the coils of draw wire to be deposited by gravity on to an independent receiver.  Receivers are replaced in a matter of seconds and since the coil

Comment:


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produced can be 1 ton or more, stoppages are few with consequent efficiency of a very high order.  Since drawing block and receivers are connected the whole virtually becomes a large block effectively supported at both ends.  Gravity blocks are now used extensively on all classes of wire, for take-up frames, and finishing blocks of multiple hole machines. arranged with collapsible legs on galvanizing take-up frames, coils of pre-determined weight can be tied up and deposited on to a stillage while the next coil is being collected. New installations use double draft gravity blocks in line with cleaning systems producing finished wire drawn two holes direct from rod in 1 ton coils.
Ground    An electrical term meaning to connect to the earth or other large conducting body to serve
as an earth thus making a complete electrical circuit.
Ground -    An electrical term meaning to connect to the earth or other large connecting body serving as an earth, thus making a complete electrical circuit.
Ground Support Cable   A cable construction, usually rugged and heavy, for use in ground support control or power systems.
Ground-loop noise.    Noise that results when equipment is grounded at ground points having different potentials and thereby creating an unintended current path.  The dielectric of optical fibers provides electrical isolation that eliminates ground loops.
Grounded Conductor    A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes; usually colored green.
Grounded neutral.    The neutral wire is metallically connected to earth.
Guillotine shears.    Metal shears in which a cutting blade drops down and shears the metal off.
Hard Drawn -    Wire that has been drawn to a specific size without being annealed.

Hard Drawn Copper
Wire

Copper wire that has been drawn to size and not annealed.

Hard drawn.    Refers to the temper of wires that are drawn without annealing or that may work harden in the drawing process.
Harness    A term used to describe a group of  conductors laid parallel or twisted by hand, usually with many breakouts, laced together or pulled into a rubber or plastic sheath, used to interconnect electrical circuits.
Harness -    An assembly of conductors grouped and bound together in a fixed configuration to be used as circuitry or a given application.  i.e.:  Automotive wiring harness, aircraft wiring
harness.
Hash Mark Stripe    A non-continuous,  helical stripe applied to a conductor for circuit identification.
HDP -    High density polyethylene.
Heat Distortion    Distortion or flow of a material or configuration due to the application of heat.
Heat Seal    In cabling, a method of sealing a tape wrap jacket by means of thermal fusion.
Heat Shock    A test to determine stability of a material by sudden exposure to a high temperature for a short period of time.
Heavy rod.    Wire rod in sizes falling between 9.5 and 18 mm. dia.
Helical Stripe    A continuous, colored, spiral stripe applied over the outer perimeter of an insulated conductor for circuit identification purposes.
Helical wire.    Wire with a general cross-sectional  shape which is non-circular and of which the orientation varies helically along the length of the wire.  Used for threaded nails, spikes, concrete reinforcement, non-skid gratings, etc.  Produced by helically twisting wire about its longitudinal axis or by rolling or grooving completed nails, screws, etc.  A Canadian patent process involves drawing the wire through a non-circular die which is helically twisted about its axis while the wire is being drawn.  Square shaped wire is also passed through a revolving square die at the nail machine inlet to form twisted nails.
Helix    A spiral winding.
Helix -    A spiral winding.
Henry    An electrical unit denoting the inductance of a circuit in which a current varying at the rate of one ampere per second produces an electromotive force of one volt.
Henry.    The measure of inductance, defined as the inductance of a circuit in which a counter


electromotive force of one vole is generated when the current is changing at the rate of one ampere per second.
Hertz (Hz).    A term replacing cycles-per-second  as an indication of frequency.
Hessian.                                    Used as a wrapping for coils of wire during transport. Must be free of acids of anything likely to promote corrosion.  Impregnated hessian, treated to protect wire or bright steel parts against corrosion and rusting is also available.  It is claimed to give full protection under all humid and acidic atmosphere conditions likely to be encountered in transit and storage, only a single wrapping being necessary even under extreme conditions.
High carbon.    Material containing a comparatively high percentage of carbon (usually 0.6 to 0.8 percent
C.) e.g. rope wire, piano wire.

High conductivity copper.

Copper, which in the annealed condition has a minimum electrical conductivity of 100 percent IACS. Electrolytically refined and fire refined coppers to BS 1036 and 1037 respectively both meet this requirement.

High voltage.    Usually understood to mean a voltage exceeding 650 volts.
HMP -    High molecular weight polyethylene.
Hochstader cable.    A screened cable (q.v.) in which each core is fully insulated and provided with a layer of metal tape of metallized paper.  A copper-woven fabric tape is applied over the laid-up cores to ensure contact between the core screen and the lead sheath.
Hole.    The hole in a drawing die.  Also used in the same sense as the word "pass".  A wire drawn through one die only is said to be one holed or single holed.
Hook-up Wire    A wire used for low current, low voltage (under 1000V) applications internally within enclosed electronic equipment.
Horizontal Stripe    A colored stripe running horizontally with the axis of a conductor, sometimes called a longitudinal stripe, used as a mans of circuit identification.
Hose armoring wire.    Round, flat or half-round wire in various sizes, with a galvanized finish in hard or soft mild steel and high tensile steel.  Sizes usually 0.9 to 1.6 mm. dia.
Hot Dip    A term denoting the covering a surface by means of dipping the surface to be coated into a molten bath of the coating material.
Hot Dip -    A term denoting the coating of a surface by means of dipping it into a molten bath of the coating material.
HV -    High Voltage.
Hybrid Cable    A multi-conductor  cable containing two or more types of component.
Hybrid Cable -    A multiconductor  cable containing two or more types of cable and/or metal.
Hydrostatic extrusion.    This process forces a billet through a die by using a fluid in place of a ram.  The billet is placed in a container and nosed to fit a conical die in one end of the container.  The billet
is completely surrounded by a fluid which can be pressurized by forcing down a plunger or by other means.
Hygroscopic -    Readily absorbing and retaining moisture.
Hygroscopic.    Readily absorbing and retaining moisture.
Hypalon®    Dupont trademark for chlorosulfonated  polyethylene (CSPE) synthetic rubber.
I.A.C.S.    International Annealed Copper Standard.  Copper which in the annealed condition has a resistance equal to that in the standards laid down by the International Electro-Technical commission (I.E.C.) is said to have a conductivity of 100 percent I.A.C.S.  Annealed high conductivity of 101 percent or almost 102 percent.  The I.E.C. standards are that at a t temperature of 20 deg. C.  (1) the resistance of a wire of standard annealed copper 1 meter long and of uniform 1 sq. mm. section is 0.017241 ohm; (2) the constant mass temperature co-efficient of resistance is 0.00393 per deg. C.; (3) the density is 8.89 gm. per cu. cm; (4) the resistance of a wire of uniform section 1m. long and weighing 1 gm. is 0.15328 ohm.
IACS -    International Annealed Copper Standard.
ID -    Internal Diameter.

Idler.    A sheave or roller used to guide or support a rope or wire.
IDP    integrated detector/preamplifier.


Ignition Cable    A cable designed primarily for automotive ignition system.
Impact Strength    A test designed to ascertain the punishment a cable configuration can absorb, without physical or electrical breakdown, by impacting with a given weight, dropped a given distance, in a controlled environment.
Impact test.    A test to determine the toughness, or resistance to shock or impact, of a material.  The energy absorbed in fracturing a test piece, usually notched, by a blow of high velocity is determined.  The most common tests are Izod, Charpy and Fre′mont, each having its individual test piece dimensions and method of delivering the blow.
Impedance    The ratio of the effective value of the potential difference between two terminals to the
effective value of the current flow produced by that potential difference.
Impedance -    The apparent resistance to flow of an alternating current.  Generally expressed in ohms.
Impedance.    The total opposition (i.e. resistance and reactance) a circuit offers to the flow of alternating current.  volts per ampere; ohms.

Imperial standard wire gauge.
Impregnated pressure cable.

More usually known as Standard Wire Gauge.

A mass impregnated paper-insulated  cable with a mechanically reinforced lead sheath in which the space inside the lead sheath is brought up to a high pressure by the introduction of inert gas in contact with the dielectric.  Appreciable sheath clearance is required for single-core cables while lead pipe gas channels are included in three-core designs.


Impregnation  of cables.    In the Mass Impregnation process (see also preimpregnated  Cable) paper insulated cables are wound on a drum or in a circular tray which is placed in a heated tank to dry the insulation at low pressure (see Vacuum Drying).  Hot impregnating compound is then admitted and the vessel maintained at about 120° C. under positive pressure.  The total drying and impregnating time is of the order of 20-70 hours depending on cable type and voltage.  In the case of solid type cables the compound is pumped away and the drum or tray removed from the tank for the metal sheathing process.  With oil-filled cables, however, the tank is connected by a pipe to the sheathing press and the cable is sheathed while full of oil.  An alternative procedure for oil-filled cables is to carry out the metal sheathing after drying the cable and then to impregnate by passing the compound through the cable.  The cable is on a drum in a heated tank.
Inching.    Easing a drawing machine slowly when threading up.  This is usually provided for in the electric controls, magnetic clutches, plate clutches or similar mechanical devices.
Inclusion.    A nonmetallic inclusion formed by reaction within a metal or trapped in the metal during manufacture.

Independent wire rope core.

Known as IWRC.  A wire rope used as the core of a larger rope.

Index of refractions.    The ratio of the velocity of light in free space to the velocity of light in a given material.
Symbolized by n.

Index-matching material. Individual Strand Diameter-

A material, used at optical interconnection,  having a refractive index close to that of the fiber core and used to reduce Fresnel reflections.
The diameter of an individual strand of a stranded wire.

Inductance    That property of an electrical circuit by virtue of which a varying current induces an
electromotive force in that circuit, or in an adjacent circuit.
Induction heating.    Heating by means of electric eddy currents which are induced within the metal by a coil carrying usually high frequency alternating current.  The depth to which the currents penetrate, ie the depth of heating, is dependent on the frequency of the magnetic field which generates the current.  The frequency of the electrical supply must be chosen to suit not only the application but also the product material and its size and form.  In surface hardening applications, induction heating has the ability to heat quickly to a precisely controlled case depth over the whole or any required part of a product.
Infra-red heating.    A drying process for wire and fabricated wire goods, usually after dip-coating.  The


material is transported through a tunnel unit lined with infra-red lamps.  A tungsten- filament, quartz tube lamp radiates 1kW from a tube about 300 mm long and less than 12 mm dia.  A further projected use of this lamp is for prolonging forging times on different materials, eg nimonics.
Ingot.    The solidified mass of metal resulting from the pouring of molten metal into a mold.  It usually has a round or rectangular cross-section with rounded corners, and the greatest dimension is always the vertical.  Ingots are always tapered and usually cast big-end-down.
Inhibitors.    Inorganic or organic substances which are added to the pickling bath for the purpose of retarding the chemical action of the acid on the steel, while allowing it to continue on the iron oxides and scales until they are dissolved or removed, and the steel surface is perfectly clean.  They also assist in preventing hydrogen embrittlement.   The quantity of inhibitor added to the acid usually varies between 0.05 and 0.1 percent.  Other requirements for an inhibitor are: it must not lose its effectiveness at higher pickling temperatures; the surface of the pickled wire must not get dirty through its use; it should be easily soluble and leave no trace in the acid; it should not foam so strongly that it
becomes withdrawn from the acid; it should not deteriorate with storage; and it should not cause difficulty in acid recovery processes.
For inhibiting attack on aluminum and aluminum alloys, inhibitors are often employed in pairs, and silicates and chromates, or silicates and phosphates, are found in some cases to be more effective than the equivalent concentration of each used singly.  A well-known instance of the effectiveness of two inhibitors used simultaneously in inhibiting attack on aluminum compositions is the use of metasilicate and chromate.
Inlet wire.    The wire entering the first die of a drawing machine.
Inner wires.    All wires of a strand except surface or cover wires.
Insect screen wire.    A low carbon hard drawn wire with a finish suitable for electro-galvanizing or painting of the woven cloth.  May be bright, coppered or galvanized.  Common sizes are 0.27 mm. for the warp wires and 0.3 mm. for the weft wires.
Insertion loss.    The loss of power that results from inserting a component, such as a connector or splice, into a previously continuous path.
Insulated Conductor -    A conductor to which an insulating material has been applied to withstand a predetermined voltage gradient.
Insulation    A non-conductive  material usually surrounding or separating two conductive materials.
Often called the dielectric in a radio frequency cable.
Insulation -    A non-conductive  material usually surrounding or separating two or more conductive materials.
Insulation of a cable.    The insulation of a cable is that part which is relied upon to insulate the conductor from other conductors or conducting parts or from ground.
Insulation Resistance    That property of an insulating material which resists electrical current flow through the insulating material when a potential difference is applied.
Insulation Resistance -    As applied to wire and cable, is the amount of resistance offered by the insulation on an insulated conductor to leakage current usually expressed in meg ohms per 1000 ft.
Insulation Shield -    A layer of semi-conducting  material or tape applied directly over the insulation of high voltage cables, usually on cables rated at over 5000 volts.  In addition to this layer, some cable constructions include a layer of non-magnetic metal overlapping tape or a number of helically applied small wires.
Insulator -    A non-conducting  substance such as porcelain, plastic, glass, rubber, etc.
Integral Belt    In a cable, a layer of insulation or semi-conductive  material applied usually by extrusion over two or more insulated, twisted or parallel conductors, to form a round smooth diameter.

Integrated detector/preamplifier.

A detector package containing a pin photodiode and transimpedance  amplifier.

Interconnecting Wire    A type of wire for external use in electronic equipments where exposed to physical abuse.
Interconnection  wire encompassed both control and power circuits.


Internal Diameter -    The diameter of some internal part or composite of an object which in this case would pertain to wire, cable, etc.

Interstice    In cable construction, the space, valley or void left between or around the cabled components.
Interstices -                        A space between one thing and another, as between conductors in a cable.
Inverted block.    Suspended from a stand so that the coils of drawn wire are deposited by gravity onto an independent receiver which hold 1 ton or more of wire and can be quickly replaced. Further details are given under the entry for gravity block.
Ionization                        The act of splitting into or producing  ions. Ionization -                         The act of splitting into or producing ions. IPM -                                    Inches per minute.
IR -                                       Insulation resistance.

Irradiation    The exposure of a material to high energy emissions.  In insulations for the purpose of favorably altering the molecular structure.
Irradiation of polythene.    The structure and properties of conventional polythenes are modified by subjecting polythene insulated cable to radiation.  In one installator tube in the generator is scanned electro-magnetically so that it emerges as a beam having its longer axis parallel to that of the cable; it is thus possible to process the cable continuously.  Among other advantages, a substantially raised softening temperature results from irradiation.
Irradiation.                              A process by which an insulated wire is exposed to an electron beam to change the molecular structure of a coating.  Improved dielection properties including a higher melting point are achieved.
ISO                                       International Standard Organization.
Izod test.    A test for resistance to impact by measuring the force required to break a test piece 1 cm square with a notch in it of 2 mm depth by striking it with a pendulum hammer from a predetermined  distance.   The energy required to break off the free end of the sample is a measure of the impact strength or toughness of the material.
Jacket                             A material covering over a wire insulation or an assembly of components.  An overall
jacket on a complex cable grouping is also often referred to as a sheath.
Jacket -    A covering put around an insulated conductor for the purpose of protection and/or resistance.
Junction Box -                   A box used in an electrical circuit to enclose and permit access to electrical connections.
KCM -                                  1000 circular mils (see Circular Mil).


Keystone strand wire rope.

A type of rope in which the wires of the strands are of a keystone or wedge shape, so arranged that when the rope is in use the wear is evenly distributed over its outside surface.

Kilocycle    A term denoting one thousand cycles. Kilovolt    A term denoting one thousand volts. Kilowatt    A term denoting one thousand watts.
Knurling.    Rolling a pattern on wire (or other material) by means of a special tool.
KV -    Kilovolt (1000 volts)/
KVA -    Kilovolt ampere (1000 volt x amperes).
KWH -    Kilowatt Hours (1000 watt hours).
Lacquer    The term used in cable manufacture to designate the liquid resin or compound applied to a fibrous braid to prevent fraying, wicking, moisture absorption, etc., in the braid.
Lacquer Finish -    A finish applied over braided wire on cable for appearance, for moisture-proofing, to reduce friction and resist abrasion.
Laminated Tape    A term used to describe a tape consisting of two or more layers, usually each layer being a different material, sealed or laminated together to form one tape.
Laminates -    A build-up of layers of material to increase thickness.


LAN    Local area network.
Lang's lay wire rope.    Wire rope in which the wires in the strands and the strands in the rope are laid in the same direction.
Lanolin.    A grease used as a wire drawing lubricant and as a basis for grease type rust preventives.
Also known as wool fat or degras.
Lapping machine.    See  Taping machine.
Lapping.    (1) Winding one wire round another; (2) A polishing process due to the relative motion between a soft surface, in which an abrasive is embedded, and the surface to be polished, as in the polishing of wire drawing dies.
Laps.                                         (1) Folds of metal due to over-filling of any given pass which are folded over and rolled in on entry into the next pass.  The lap becomes apparent in the finished rod after further cold working or when any standard metallurgical tests are carried out. (2) Turns of wire round a capstan or block.
Laser gauging.    A process based on laser and electro-optical technology used for the inspection of parts such as pins, bolts and rivets at speeds up to 600/min.  A helium-neon laser generates a collimated beam of light which is optically focused, processed and split into three beams. One beam is stationary and acts as a reference, while the other two beams move with differential motion and define the "tolerance band".  The parts are fed automatically past the inspection beams and the interruption of these beams generates a sequence of events which indicate the length of the product.  Photo detectors convert the information to electrical signals for logic processing.  Electronic analyzing is then performed and any part found to be out of tolerance is rejected.
Laser.    A narrow and intense beam of light which can be focused in such a way that a very high energy density is attained at the point of focus.  See details of laser drilling under the entry for die manufacture.
Laser.    A light source producing, through stimulated emission, coherent, near monochromatic light.  Lasers in fiber optics are usually sold-state semiconductor  types.

Lateral displacement loss.

The loss power that results from lateral displacement from optimum alignment between two fibers or between a fiber and an active device.

Lay    A term used in cable manufacturing to denote the distance, of advance of one member of a
group of spirally twisted members, in one turn, measured axially.
Lay -    The distance taken to complete one revolution of helically laid strands or strand of wire around a central core.
Lay Direction -    The direction in which the members of a cable are applied, the direction of the twist, normally referred to as left hand "S" or right hand "Z".  The direction in which the strands diverge from an observer when looking perpendicular to a cable end.
Lay.                                           (1) The manner in which wires are helically laid into strands or strands into rope.  (2) Part of a weaving loom, also known as a slay or batten, which operates horizontally across the loom and which beats the wire into position during cloth weaving.
Length of lay.  The pitch or axial length of one complete turn of the helix formed by a single wire in a strand, or core in a laid up cable, or paper tape on an insulated core or cable.
Lay ratio.  The ratio of the axial length of a complete turn of the helix formed by the wire of a stranded conductor to the mean diameter of the helix.
Layered cable.    The older type of subscribers' telephone cable which has been largely superseded by unit cables (q.v.).  In the manufacture of layered cable, the reels of the stranding machine carry paired or quadded conductors, which are twisted together so that the conductors from the first carriage form the core of the cable, while those from subsequent carriages, which rotate in opposite directions, form layers over this.  Production of layered cables
eventually reached the point where the diameter of the smallest conductor was reduced to
0.4 mm. and the number of circuits was increased so that an 1818-pair cable required 26 layers, necessitating four or five passes through even the largest strander.  A similar unit cable requires only two passes and its diameter is smaller.  Conductors used in layered


type subscriber cable are usually of 0.4, 0.5, 0., 0.63 or 0.9 mm. dia.
Laying reel.    A stationary reel for taking up hot wire rod after rolling, the rod being distributed into a coil by a revolving delivery pipe or by a delivery pipe ending in an arc which causes the rod to coil by starting it on a circular path.  Not suitable for sizes above about 9.5 mm dia., because the rod is given a twist as each ring of the coil is formed.  Accepts rod at high speed because the coil is stationary and forms a more compact coil than the pouring reel (q.v.).  Mills handling both large and small diameter rods are usually equipped with both laying and pouring reels.
Laying-up machine.    Similar in principle to a stranding, but is used for laying-up or twisting together in helical form round or sector shaped insulated cores of a multicore cable.  The cores, with paper rubber, plastic or textile fillers placed at the interstices are led from bobbins through the lay plate in pre determined sequence and then drawn through a closing die to ensure that a compact circular cross-section is obtained.  Reels for use with these machines are described in the entry under reels.
Lead baths.                              Used for cooling after heat-treatment processes; gives much better heat transfer properties to many materials than when cooled in air.  The properties of heat treated products depend on the cooling rate.  Must be kept at 400 to 550 deg. C.  When used with the lead
patenting process gives approximately 5 tons higher tensile than that obtained when air patenting and also provides a more uniform metal structure.  Heating means are provided, but these are not normally needed when the plant is running, and heat carried into the lead by incoming rod necessitates forced air cooling.  More uniform temperature can be obtained by recirculating the lead.
Lead coating.    Was widely used for many years as a carrier coating for stainless and austenitic wires as it was the only means of obtaining an adequate bonding surface for dry lubricants to permit multi-hole reductions at reasonably high speeds.  Has since been largely superseded by oxalate and then other chemical coatings which are easier to apply and in particular do not present the very great difficulty experienced in removing lead coatings satisfactorily even after lengthy acid pickling.
Lead patenting.
LED    Light-emitting diode.
Life Cycle    A test performed on a material or configuration to determine the length of time before failure in a controlled, usually accelerated, environment.
Light metal.    A loose term which is usually understood to mean a metal with a specific gravity below
3.8.
Light rod.    Wire rod in sizes falling between 5 and 9.5 mm. dia.
Light-emitting  diode.    A semiconductor  diode that spontaneously emits light from the pn junction when forward current is applied.

Line Voltage -    The voltage existing in a phase conductor in an electrical circuit, either phase to ground
(neutral) or phase to phase.
Litz Wire    A conductor made up of several insulated twisted wires to reduce skin effect and lower radio frequency losses.
LMP -    Low molecular weight polyethylene.

Loaded cable.    An electric cable in which inductance is added along its length to reduce transmission losses.
Local area network.    A geographically limited network interconnecting electronic equipment.
Locked coil rope wire.    Wire shaped so as to lock with other connecting wire units to form locked coil wire rope.
To allow the point to pass through the die without fracture when commencing drawing, it
is necessary first to flatten it, and then groove the flat sides.  In fitting the point through the die, the rod should be placed that the grooves fit the projections.
Locked-coil conductor.    A stranded conductor in which the outer wires are so shaped that when assembled with a lay they are locked in position against radial movement.


Longitudinal Wrap    A tape applied longitudinally with the axis of the core being covered, as opposed to a helical, or spiral, tape wrapped core.
Longitudinal Wrap -    A tape applied longitudinally with the axis of the core being covered, as opposed to a helical, or spiral, tape wrapped core.
Loop Resistance    The total resistance of two conductors measured round trip from one end (twisted pair, shield and conductor, etc).
Loss Factor    The loss factor of an insulating material is equal to the product of its dissipation and dielectric constant.
Low Loss Dielectric    An insulating material, such as polyethylene, that has a relatively low dielectric loss making it suitable for transmission of radio frequency energy.
Low Noise Cable    A cable configuration specially constructed to eliminate spurious electrical disturbance
caused by capacitance changes or self generated noise induced by either physical abuse or adjacent circuitry.
Lubricants.    Two distinctive forms of lubrication are principally employed in wire-drawing  dry lubricants in the form of a solid dry soap compound, wet lubricants, which may be a wet pastel-like solution or emulsion, or a straight liquefied mineral or other type of oil.  In general, it is customary to use dry lubricants for dies drawing ferrous wires.  The wet system is largely confined to the drawing of the softer and more ductile nonferrous metals and alloys; steel wire coated with a thin  layer of some nonferrous metal, usually copper, is also drawn by the wet method, and in this case predrawing through one or more dies lubricated with dry soap is beneficial.
Distinction must be made between drawing to size and drawing for surface finish.  In the former, the aim is to draw the wire in the least number of passes and at the highest rate of output; the thickest possible film of lubricant is then desirable in the interests of lower friction and greater heat capacity.  When drawing to surface finish, the film should be thin, so as to give full rein to the smoothing action of the die which is assisted by high friction.
Dry lubricants.  Solid compounds usually having a sodium base and admixed with olive oil or aluminum stearite, or other additives to promote anti-welding, wettability, etc. Dry sodium soaps provide a lubricant film which will remain effective over a number of successive drawing operations if suitably applied.  Under pressure in the die, the soap forms an adherent plastic film of lubricant.  With increased drawing speeds, calcium soaps containing high-melting-point fillers such as lime have been introduced, the filler serving to raise to higher temperatures the persistence of a mixed solid-liquid phase.
The soap contained in a soap box is liable to "channel" and leave a clear passage in which the wire does not pick up lubricant; this can be overcome by an agitator in the soap box.  A more thorough and longer lasting coating of soap can be obtained using a nozzle die unit (q.v.) which serves to force the dry lubricant into the die.  By sull-coating after pickling steel wire, an oxide coating is formed which after lie coating forms a layer of suitable composition for the soap to adhere tenaciously.
Dry sodium soap, however, has several disadvantages.   It will not produce a high polish on the wire, it is frequently difficult to remove, it may cause an objectionable residue when the wire is annealed, and it does not have the physical cooling and heat dissipating powers of wet lubricants.  Also if the coating put on by passage through the first die is destroyed,
it cannot be renewed at the following dies and rapid die wear takes place.  For this reason,
non-slip machines are used for dry drawing o preserve the coating.  Considerable advantages have been claimed in recent years for borax and phosphate coatings to replace liming, particularly in regard to cleanliness, more exact control of the coating, and the fact that the coated rod or wire can be stored for longer before drawing.
Wet lubricants.  There are many wet lubricants available for general application and others which have special properties such as heat dissipation, and welding features, good wettability, etc.  These lubricants are usually in the form of solutions or emulsions, having water as the main content to a variety of concentrations to suit working requirements.   The paste-like mixtures usually formed are particularly east to handle, apply and store.  They


comprise compositions of water, vegetable or other fats and certain fatty acids or oils.
The mixtures are suitably saponified or emulsified by the addition of sodium, aluminum and potassium mineral soaps, frequently admixed with small quantities of such substances as light mineral oils, water-soluble oils, hydrogenated oils, surface-active chemical agents, inhibitors, germicides and other special additives to impart particular properties.  The commonest fat constituents are lard oil, rape seed oil, palm oil, tallow, or the sulphonated and hydrogenated oils.  The fatty acid content has to be controlled according to the wire to be drawn and the process used.  For drawing steel wire, there may be as much as 2 to 3 percent of free fatty acids.  It is essential that the wet drawing lubricants are cleaned to avoid build-up of cooper soap deposits and also to remove small metal particles.  This is best achieved by a system of settling tanks.
An abundance of hard water causes soap to be deposited, which has a detrimental effect on the stability of the grease content in the lubricant.  Soap deposits may block up the entrance of the die and lubricant holes of the wire-drawing machine.  The most favorable working temperature for emulsion lubricants are between 38 and 55 deg. C.  Higher temperatures will result in a shorter life of the dies.
Optimum results are obtained when the pH value of the emulsion lies between 8.5 and
9.6  Carbon dioxide reduces the phH factor hence it is recommended that the settling tanks should be kept closed.  Pickling acids will also reduce the pH value; their presence will soon be evident from the greenish tinge which the lubricant assumes.  The pH factor can
be raised again by adding an alkaline substance, for example 60 g. of caustic soda per 450 liters of lubricant, repeating after a few hours if necessary.
The appropriate grease content varies with the type of drawing.  A suitable grease
content for copper would be 7 percent for 2.5 mm. dia., reducing to 4 percent for 0.18 mm. and to 1.5 percent for 0.015 mm.  Heavy foaming because of a high grease content can be neutralized by using a commercial silicone based anti-foaming agent.  Grease content can be determined by adding 7 cc. of hydrochloric acid to 100 cc. of lubricant in a graduated flask and heating to 75 deg. for 15 to 20 minutes.  The reading in cc. of the grease floating on the surface represents the percentage of grease in the emulsion.
Experiments on increasing die life in copper wire-drawing have suggested that the "suds" solution used as both lubricant and coolant is rather a poor lubricant for the dies and changes in the design of copper wire-drawing machines to separate the lubricant and cooling functions might be an advantage.  When a small separate quantity of lubricant is used to lubricate the final die it is possible to keep this clean much more readily than the main body of the water-oil coolant and lubricant; there is less metallic debris and the wire emerges exceptionally clean.
Drawing oils and greases.  Usually mineral or vegetable oils, soluble oils compounded oils, wax mixtures, and other oil-based fluids.  These lubricants are being increasingly
used for drawing "difficult" metals such as stainless steel, nickel-chrome steel, Monel, etc. thus obviating troublesome lead coating and subsequent removal of this coating.
Aluminum wire.  The principal lubricants employed in aluminum drawing are compounded mineral oils, as these are superior to water solutions or emulsions for the drawing of this metal.  Aluminum is subject to attack by alkaline solutions and also water stains, which make their employment in the drawing of this metal unsatisfactory.   Mineral oils, in addition to producing a good finish, are less liable to stain the metal during any subsequent heat treatment.  Nevertheless the comparatively heavy mineral oils used for some purposes can be only partially decomposed to cause straining of the inner interstices of the coil during heat treatment, particularly of strip.  The amount of oil remaining on the wire or strip has to be minimized in such cases.  Controlled atmosphere or vacuum furnaces also offer a solution.
Aluminum and its alloys resist effective "wetting" by fluids, and additions of wetting agents are therefore necessary.  Mineral oils of fairly high viscosity with a small percentage of additives are used for heavier drawing, lower viscosity oils for smaller


diameters and soluble oils for fine wires.  Lubricants are usually recirculated and cooled to assist in preventing a temperature rise sufficient to cause softening of the metal.
Copper wire.  Copious quantities of wet lubricant are required in copper drawing to provide adequate cooling.  These lubricants are usually over 90 percent water, containing only 0.5 to 0.75 percent fat for fine-wire machines.  The quality of water used in preparing the lubricant is therefore very important.  Excessively hard water causes precipitation of soap in the lubricant, affecting the stability of the fat emulsion.  This tends to clog the dies, and possibly the pipelines of the lubrication system, resulting in surface particles from the wire being retained in the bell and throat of the die; this causes heavier die wear.
Wire-drawing or rod pastes consist of a mixture of fats, soaps, fatty acids and mineral oils; also they may contain free alkali content, usually potash or soda ash.  The fats most frequently used are tallow, lard, woolgrease, beeswax, and rape seed oil; they are rendered emulsifiable by partial saponification or sulphonation.  The soaps, when used, are sodium or potassium soaps according to circumstances.   The mineral oil used is general spindle
oil.  Dry lubricants may be used for the slower drawing operations; these are generally dry soaps, such as sodium soap of olive oil, or calcium stearate. Undiluted rod paste, beeswax, tallow, woolgrease or compounded vegetable and mineral oils may also be used. Degreasing, or immersion in boiling water, may be necessary if the wire is required
entirely clean for a subsequent operation.
Used mainly for drawing finer wires, soluble oils usually consist of a mineral oil plus an emulsifier, and are used in similar concentrations to the wire-drawing pastes.  Ideally, the wire-drawing machines should be fed in batteries from a common supply center as this gives a better opportunity of cleaning the liquor.  The most suitable working temperature of the solution usually ranges from 34 to 72 deg. C., a temperature over 72 deg. C. resulting in reduced die life with most compounds.
Stainless steel, nickel chrome, etc.  These metals and others such as Monel have presented difficulties in processing because of their tendency to rapid work-hardening,  and because it is not easy to produce a matt surface, apply lime coating or produce an adequate bonding surface for a dry soap lubricant by traditional means.  For this reason, in spite of its high cost and difficulty in removing it, lead coating was used over many years as the only consistent means of obtaining multi-hole reductions at reasonably high speeds.  The position was considerably improved with the introduction of oxalate coating particularly when the process was modified to give quicker and constant results provided that the correct procedure is carefully followed.  The oxalate coating is formed by a chemical reaction between the metal surface and the coating.  A later and widely used
nonconversion coating - a combined carrier/lubricant,  suitable for dry drawing of ferrous and nonferrous metals, particularly in stainless steel - needs no complicated pre-treatment and the bath is very easy to operate and control.
Tungsten and molybdenum.   For hot drawing tungsten and molybdenum, graphite is supplied in the form of a colloidal suspension in water (usually about 18 percent graphite) or as a fine suspension in oil; it is usually then diluted with distilled or demineralized water.  Complete homogenization  is of the utmost importance, and the lubricant must be very thoroughly mixed before use and after standing overnight.  Where wires are required in the as-drawn condition, chemical means are used for removing residual lubricant. Where a final anneal is necessary, annealing and cleaning are carried out simultaneously,
common practice being to use hydrogen saturated with water vapor at room temperature to assist in removal of graphite.
Cleaning of lubricants.  The fine particles of metal which would otherwise damage the dies and perhaps the wire being drawn are removed from the lubrication system of wire- drawing machines by means of a settling tank or by magnetic filtration.  A settling tank needs to be large if it is to be fully effective, with a 30 to 40 minute settling time and a conveyor to drag out sludge.  The flotation process is designed to act as a settling aid in a small settling tank to which contaminated coolant is pumped from a number of machines.


Electrochemical  lubrication.  Lubricants can be formed on any conducting surface connected as an anode in an electrolyte.  Molybdenum wire can be coated with molybdenum disulphide from a multen salt bath containing sodium disulphide. Thioacetamide  and ammonium molybdate in solution at room temperature deposit a lubricating coating on other wire under the influence of current and potential.  Research results appear to indicate reduction of friction equal to that obtained with molybdenum disulphide paste.  Coating takes several seconds and for high speed drawing a very long tank or multiple loops would be necessary.  The coating can be removed in a second electrolyte tank by passing a fairly large alternating current.
Hydro-dynamic  lubrication.  Lubrication which provides a continuous fluid film so that metal to metal contact in the die is largely prevented.  With wet lubricants, this is achieved by passing the wire through a tube with small clearance, firmly attached to the die.  This constricts the free flow of liquid fed to the tube entrance and pressure builds up in it.  Materials possessing yield strengths less than that of hard carbon steel wire can be drawn effectively (under conditions of hydrodynamic lubrication) from rod.  Equipment
has been designed which works effectively within this material strength limitation enabling different materials to be drawn with the same lubrication system without pre-coatings.
Hydrostatic lubrication.  A method of lubrication wire-drawing dies where the lubricant is kept under pressure.  The main pressure chamber, cylindrical in shape, has a central bore providing clearance for the wire passing through, and tappings are provide for pressurized-lubricant entry, pressure-gauge  connection, and bleed holes.  Two dies are fitted, on at each end of the pressure chamber.  Lubricants of any selected viscosity can be used providing the pressurizing source can handle them.
Removal of lubricants.  Water soluble coatings, such as borax and sodium stearate, can be removed quite simply by washing in hot water or dilute hot alkaline solutions.  The
more common insoluble lubricants, such as lime and calcium soaps, require more severe treatment and most methods employ acid cleaning, sometimes accelerated by electrolytic or ultrasonic action.  For ultrasonic removal of lubricants, the equipment used is similar to that described under the entry for pickling, but the cleaning chemical is different in each case to suit the lubricant concerned, while the chemicals are used in the ultrasonic tank rather than in a tank preceding it.  With a mildly acidic or alkaline detergent at low concentrations  and a temperature of about 40 to 60 deg. C., for example, ultrasonic cleaning will remove the persistent sticky soap often found on stainless steel or alloy wire in less than 10 sec.  Oxide and dust remaining on copper after sulphuric acid pickling can be removed with ultrasonic equipment to avoid longer immersion in the acid.
Lug    A term commonly used to describe a termination, usually crimped or soldered to the
conductor, with provision for screwing down to a terminal.
Magnesium (Mg).    The lightest of all atmospherically stable metals, is a silvery-white metal which tarnishes easily in moist air.  Forms a number of light alloys with aluminum which have wide uses in aircraft construction.  In one patented process, to increase ductility of magnesium wire during drawing reductions, it is heated to a temperature between 163 and 278 deg. C. and held at this temperature for initial reductions.  Thereafter the resulting wire is heated to a lower temperature between 153 and 56 deg. C. and held there down to final reductions.

Magnetic Field    The region within which a body or current experiences magnetic force.
Magnetic Field -    The region within which a body or current experiences magnetic force.
Magnetic Flux    The rate of flow of magnetic energy across or through a surface (real or imaginary).
Mandrel drawing.    The original method of tube production using a fixed mandrel bar. It is uneconomic in that much time outside the drawing cycle is consumed in loosening and extracting the mandrel bar.  Still used for the production of thin-walled tube and also for the production of very large tubes.
Mandrel test.    A test to determine the adherence of a galvanized coating on wire, in which the wire is wound round a mandrel, the diameter of which is a predetermined multiple of the wire


diameter.  Also known as the wrapping test.
Mandrel.    The tool round which wire is formed as for example in coiling of springs.  Originally a curved piece of wood, suitably grooved, upon which springs were made by hand.  The wire was guided by the operator with one hand along the groove while the other hand was employed in rotating the appliance by means of a handle.
Manganese. (Mn)    Included in practically all steels and increases resistance to tensile stress.  It also prevents red shortness and acts as a deterrent to coarse crystallization, usually induced by sulphur and similar impurities.  The range of manganese in mild steels is from about 0.3 to 0.6 percent, and in hard or medium steels from about 0.4 to 1 percent. The springiness of steel wire can be remarkably improved in the hardened condition by an increased manganese content (0.8 to 2 percent Mn, 0.4 to 0.5 percent C.) or by a manganese and silicon content (each about 1 percent). Austenitic manganese steels with manganese contents over 0.9 percent are suitable for mesh wire and welding wire as they have excellent resistance to wear while retaining good toughness.
Marker Tape -    A tape laid parallel to the conductors under the sheath in a cable, imprinted with the manufacturer's name and the specification to which the cable is made.
Marker Thread -    A colored thread laid parallel and adjacent to the strand in an insulated conductor which identifies the manufacturer and sometimes the specification to which the wire is made.
Marking insulated wire.    The insulation can be color-coded with pigments, striped with ink using a spiral striping machine, wrapped with sub-surface tapes beneath a transparent jacket, or marked by printing directly on to the wire with a hot-stamping machine.  A typical color marking machine applies up to three differently colored spiral stripes simultaneously and width of the stripe can be varied; it is said that one machine gives a choice of 30,000 wire color coding applications.  Hot stamp printing consists of  transferring the image from heated type to the wire surface by stamping or striking an ink-coated foil held in contact with the wire.
Material dispersion.           Dispersion resulting from the different velocities of each wavelength in an optical fiber.
Maypole braiders.    Braiders in which the carriers containing the bobbins follow a path similar to that of a maypole.  Flat maypole machines are used for the manufacture of ornamental braids, lace, etc., and these machines have been used with little basic change in design over many years.  Tubular maypole braiders are used for solid cords and for wire and cable covering,
but the high speed rotary machines, which may be two-and-a-half times as fast as a similar maypole machine and usually much quieter in operation, has made considerable progress.
Two different systems of tracking and propulsion are in general use for maypole braiders.  Simpler of the two is the slide plate braider, common in England and America, and so named because of the sliding action of the carriers as they are propelled round the tracking by horngears.  The other type, favored largely by European  manufacturers,  has the advantage that the main carrier tracking system is underneath the top plate and is arranged in such a way that the carriers are carried round on the rotating horngears, thus allowing the tracking to be used as an oilbath for the carrier track followers.
Medium voltage.                     Usually understood to mean a voltage normally exceeding 250 volts, but not exceeding
650 volts.
Megacycle                        One million cycles.
Megahertz (MHz).                 One million cycles per second.
Megavolt                          One million volts. Megawatt                         One million watts Megohm                          One million ohms.
Melt Extrude                   To heat a material above its crystalline melt point and extrude it through an orifice.
Messenger -    A bare cable used for its strength characteristics to support power conductors and insulated power cables.  A messenger can be used as a conductor, partial conductor, or non-conductor.
MFD                                     Mode field diameter.
MFT -                                   Abbreviation for 1000 feet.


MHD -                                  Medium hard drawn.
Mho    An electrical unit of conductivity, being the conductivity of a body with the resistance of one ohm.
MI -                                       Mineral insulated (metal sheath) 85øC dry and wet location, 250øC special application.
Microfarad                       One millionth of a farad Microhenry                      One millionth of a henry Microinch                        One millionth of an inch
Micrometer -                       An instrument used for measuring diameter usually in thousandths of an inch.
Micron.                                     One thousandth of a millimeter (0.001 mm.).
Microware    A short electrical wave usually a wave length of less than 30 cm. Microwave Frequency    The frequency of a microwave usually above 1000 megacycles per second. Mil    One one thousandth of an inch.
Mil -                                      One one-thousandth  of an inch. Milivolt                            One one thousandth of one volt Milivolt -                              One one-thousandth  of a volt.
Milli-Second.                           One thousandth of a second (10 -3 second). (ms)

Milliken construction.    A term applied to a method of stranding the cores of A.C. power cables whereby the skin and proximity effects are reduced.  In a stranded cable, the skin effect results  in each outer wire carrying more current than each inner wire.  The proximity effect causes the current
to flow more readily to one side of the conductor.  In the Milliken construction, the cable is made up of at least four segments.  Each segment consists of a number of helically stranded wires, these wires being lightly insulated from one another; the segments are then laid up helically to form a cable of circular cross-section, the segments being separated from one another by strips of insulating material.  The position of each segment and of each wire relative to the center of the cable is continually shifted, and each wire tends to carry an equal quantity of current.
Mineral insulated cable.    Manufactured by inserting from one to nineteen conductors (usually high conductivity but a large variety of materials can be used) into a solid drawn metal tube, (usually copper but again many alternative materials can be used). The conductors are held in a predetermined position and pre-treated dry mineral powder (usually magnesium oxide) is fed into the tube around the conductors.  The assembly is then drawn to its final size through dies in the manner of wire drawing.  Annealing is carried out between passes to counteract work hardening and at the finished size to give the correct electrical resistance.  The main characteristics claimed are: smaller than equivalent cables, is non-aging, has great mechanical strength and is water, oil and fireproof along with a high current carrying capacity, it can operate over a wide temperature range - 200° C. + 800° C. and is ideal for flameproof applications, the sheath can be used for earth continuity and is corrosion resistant.
Mining Cable                   A flame retardant cable especially constructed to withstand long time immersion or
exposure to moisture for underground use in the environment of a mine or tunnel.
Mis-match    A termination having a different impedance than that for which a circuit or cable is designed.
Misalignment loss.    The loss of power resulting from angular misalignment, lateral displacement, and end separation.
MKS -                                   Meter-kilogram-second.
Modal dispersion    Dispersion resulting from the different transit lengths of different propagating modes in a multimode optical fiber.
Mode coupling.    The transfer of energy between modes.  In a fiber, mode coupling occurs until EMD is reached.
Mode field diameter.    The diameter of optical energy in a single-mode fiber.  Because the MFD is greater than the core diameter, MFD replaces core diameter as a practical parameter.
Mode filter.                         A device used to remove high-order modes from a fiber and thereby simulate EMD


Mode.    In guide-wave propagation, such as through a waveguide or optical fiber, a distribution of electromagnetic  energy that satisfies Maxwell's equations and boundary conditions. Loosely, a possible path followed by light rays.
Modulation.    The process by which the characteristic of one wave (the carrier) is modified by another wave (the signal).  Examples include amplitude modulation (AM), frequency modulation (FM), and pulse-coded modulation (PCM).
Modulus of Elasticity    The ratio of stress to strain in an elastic material.

Modulus of Elasticity - The

ratio of stress to strain in an elastic material.

 
Mono Filament -    A term denoting a single strand filament as opposed to a braided or twisted filament. Monofilament    A term denoting a single strand filament as opposed to a braided or twisted filament. Monomer    A term denoting a single property or ingredient.  A molecule of low molecular weight used
as a starting material for polymerization to produce molecules of larger molecular weight called polymers.
Monomer -    A term denoting a single property or ingredient.  A molecule of low molecular weight used as a starting material to produce molecules of larger molecular weight called polymers.
MTW -    Thermoplastic insulated machine tool wire 60øC wet location, 90øC dry location.
Multiconductor    More than one conductor within a single cable complex.
Multiconductor  Cable -    More than one conductor within a single cable complex.
Multimode fiber.    A type of optical fiber that supports more than one propagating mode.
Multiple twin cable.    A type of four wire or quadded telephone cable made by twisting together two twisted pairs.  Unlike star quad cables, multiple twin types can be used to provide a third "phantom" circuit by connecting across parts of wires on a crowded network  Multiple twin cables have been displaced in Great Britain and many overseas countries by the star quad type which has a lower pair capacitance and can therefore provide up to 50 percent more physical circuits of the same capacitance in a given size of cable.
Multiplexing.    The process by which two or more signals are transmitted over a single communications channel.  Examples include time-division multiplexing and wavelength-division multiplexing.
Mutual Capacitance    Capacitance between two conductors when all other conductors including ground are connected together and then regarded as an ignored ground.
Mylar -    A synthetic compound with high dielectric qualities.  A product of Dupont.  Usually sold in film form.  Dupont.
N-Conductor Cable -    A cable having N-conductors that are insulated from one another.  "N" represents the number of insulated conductors in the cable.

N-Conductor
Concentric Cable -

A cable composed of an insulated central conductor with tubular stranded conductors concentrically twisted around it and separated from each other by layers of insulation.

NA    Numerical aperture.
NA-mismatch loss.            The loss of power at a joint that occurs when the transmitting half has an NA greater than the NA of the receiving half.  The loss occurs when coupling light from a source to fiber, from fiber to fiber, or from fiber to detector.
NBR -    Natural Butyl Rubber.
NEC -    National Electrical Code.
Necking down.                        The narrowing of the diameter of a wire at the point at which a break is about to occur, as appears in tensile testing.

Needle die polishing machine.

Employs a rotating needle and revolving die spindle fed with diamond powder for polishing wire-drawing dies.

NEMA    National Electrical Manufacturers Association.  It is known in industry for its standardization  of electrical motors and gear reducers and for cable specifications.
Neoprene    Trade name for polychloroprene,  used for jacketing (SEE polychloroprene).
Neper    An electrical unit similar to decibel, used to express the ratio between two amounts of power existing at two distinct points.  A neper is 8.686 decibels.
Neutral Conductor -    In multiphase circuits the conductor used to carry unbalanced current and in single phase


systems the conductor used for a return current path.
Nickel alloys.    Some of the commonest nickel alloys include the following.
Nickel bronze.  A series of bronzes in which part of the tin content is replaced by nickel. Usual composition would be 1 to 20 percent tin, 3 to 40 percent nickel, up to 30 percent aluminum, up to 3 percent lead, and up to 12 percent zinc.
Nickel chrome.  Nickel base alloys in which iron is usually also present, used for electric resistant heating wire and heat resistant products. Nickel-chrome iron is an alloy supplied in varying content usually defined by the figures given after the name, thus -
37/18=37 percent nickel, 18 percent chromium, and the balance ferrous.  Supplied in a wide range.
Nickel-chromium-iron alloy wire for general purposes as specified in B.S. 3074
consists of not less than 72 percent nickel, 14-17 percent chromium, and not more than the following percentages of other materials: iron 10.0 manganese 1.0, copper 0.5 silicon 0.5, sulphur 0.015.
Nickel copper.  Cupro-nickel,  an alloy of copper and nickel varying in content and usually defined by the figures applied to the name, thus - Cupro-nickel 96/4 = 96 percent copper and 4 percent nickel.  Nickel copper alloy wire for general purposes as specified in B.S. 3074 consists of not less than 63 percent nickel, and not more than the following percentages of other materials: iron 2.5 manganese 2.0, aluminum 0.5, silicon 0.5, sulphur
0.02.
Nickel iron.  Wire in this alloy usually contains from 25 percent to 50 percent nickel according to quality.
Nickel manganese.  Nickel wire of this type contains up to about 15 percent
manganese; used largely for electric resistance purposes.
Nickel silvers.  White alloys consisting of copper, zinc and nickel.  The copper content usually lies between 55 and 63 percent, while the nickel ranges from 10 to 30 percent.
The most widely used grades for wire have a nickel content of between 12 and 18 percent. As the nickel content is increases, the color of the alloy changes from a very pale yellow to silver.  At the same time, the corrosion and tarnish-resisting  properties in certain media are improved.  In the annealed condition the tensile strengths of these alloys range from about
34 to 47 kg./mm.square  and increase slightly as the nickel content increases.  In the work-
hardened condition, however, the strength of all the alloys is very similar, usually being about 70 kg/mm.❷  , although for spring-temper wire, strengths as high as 86 kg./mm❷  may be attained.  Nickel silver wire is used in jewelry and for other decorative purposes, for cold heading, thread rolling, and for springs, etc.  The alloys serve as an excellent basis for
silver plating.
Nickel.    (N) As an alloying element in steel imparts a finer and more homogeneous structure. The most suitable composition for cold working is said to be 0.2 to 0.5 percent carbon and 2 to
3.5 percent nickel.  A silvery-white metal of medium hardness, highly ductile and resistance to chemical and atmospheric corrosion.  Widely used as an alloying agent in iron and copper base alloys.  When heat treating alloys containing nickel, the refractory and insulating materials in the furnace should be free from sulphur; sulphur content of protective atmospheres must also be reduced to a minimum.
NM -    Designation for nonmetallic sheathed cable, building wire
NMC -    Nonmetallic sheathed cable, corrosion resistant, 60øC wet or dry location.
Nominal (NOM) -    The preferred size or weight that is specified or indicated for a certain cable element.

Non-Contaminating
Compound
Non-slip drawing machine.

A compounded material that will not leach ingredients so as to contaminate or degrade adjacent material under given environmental conditions.
A wire-drawing machine in which the capstans run at exactly the same speed as the wire being drawn.  Usually driven by DC motors or other variable speed methods.  Used for dry drawing usually for ferrous wires.  Non-slip machines of the accumulation type with


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Nonmetallic Sheathed
Cable -

individual AC motor drive use simple electrical control gear, are consequently much cheaper, and have the advantage of better cooling facilities between reductions.  Later machines of the double block type have the advantage of producing wire without twist between reductions.
A cable assembly consisting of individually insulated conductors, jacketed, or sheathed,
with a nonmetallic material.  The material usually consists of PVC or polyethylene.

Nordel®    DuPont trademark for EPDM synthetic rubber.
Normalizing.                            Heating steel to and, holding at a suitable temperature above the transformation range, followed by cooling freely, in order to modify the grain size, render the structure more uniform and usually to improve the mechanical properties.
Numerical aperture.    The "light-gathering  ability" of a fiber, defining the maximum angle to the fiber axis at which light will be accepted and propagated through the fiber.  NA = sin O, where O is the acceptance angle.  NA is also used to describe the angular spread of light from a central axis as in exiting a fiber, emitting from a source, or entering a detector.
Nylon.    A plastic with great toughness, strength and elasticity, high melting point and good resistance to water and to most chemicals.  Its abrasion resistance is superior to polythene and PVC and because of this it is often used as a sheathing material on previously jacketed polythene or PVC cables or wires, and is simple to apply to wire or cable.  For non- electrical-uses its toughness and hardness make it especially suitable for coating heavy
duty articles such as shafts, bearings and handwheels.  It cannot be pigmented to give pastel shades required in decorative work, but can be used for wirework if the need for its special properties justifies the higher cost.
The nylon is usually applied to electrical wires or cables by one of two methods.  In the solution method it is dispersed in a liquid solvent, principally crysylic acid, and is applied as a liquid using equipment somewhat similar to that for enameling.  This method, used for wires of 0.08 to 2 mm. dia., applies relatively thin tenacious coats of nylon using a relatively small floor area, and has its greatest advantage for wires smaller than 0.9 mm. The hot melt or extrusion method, used for the largest multiple conductor cable down to about 0.5 mm. dia. single copper conductor, employs adaptation of plastic extrusion equipment to hot melt granular nylon and apply it to the wire, after-cooling being required to solidify the coat.  Speed depends directly upon nylon wall thickness.
Nylon 11 is one of the most versatile and popular plastic finishes available for coating wirework.  It has excellent compact resistance which led to its use in the furniture industry and also for supermarket self-service baskets.  It is also used for part of a dish-washing machine which must be resistant to hot detergent.
OAW -    Overall width.
OD -    The overall diameter of a cable, including conductor(s), insulation(s), jacket (if used) and concentric neutral (if used).
Ohm    A unit of electrical resistance, the resistance of a circuit in which a potential difference of one volt produces a current of one ampere.
Ohm -    A unit of electrical resistance, the resistance of a circuit in which a potential difference of one volt produces a current of one ampere.
Ohm-pound/mile    A unit of weight resistivity expressing the resistance of a wire one pound in weight and one mile in length.
Oil lubricants.    There are two types - vegetable oils and oils produced from a mineral base.  The lubricant must have sufficient viscosity at the temperature present in front of the die to form a satisfactory oil film; electrically refined oils have proved very suitable in this respect.
Oil-filled cable.    An impregnated paper-insulated  cable so designed that the impregnating medium is free to flow at all working temperatures.  One or more internal oil ducts are provided and oil is maintained under pressure by means of oil tanks connected to the cable at suitable positions along the route.  In British cables of this type the oil is kept under a pressure of




Open Standard
Interconnect.

up to about 120 kg./mm.❷
A seven-layer model defined by ISO for defining a communication  network.

Optical fiber.    Almost pure silica glass with small additions of Germanium and Borum used as the light carrier in optical fiber cables.  The lamelar light can be produced by lasers or LED's.

Optical time-domain reflectometry.

A method of evaluating optical fibers based on detecting backscattered (reflected) light. Used to measure fiber attenuation, evaluate splice and connector joints, and locate faults.


Orbital wire packaging.        Laying wire round a dead block and depositing it in orbit round a central point to obtain a low wide coil.  One type of equipment for this consists of a hydraulically driven flyer with a secondary hydraulic system driving the orbiting device.
Organic Fiber    A fiber derived or composed of matter originating in plant or animal life or composed of chemicals of hydrocarbon origin, either natural or synthetic.
Oscilloscope -    Test instrument for showing visually the changes in a varying current by displaying the corresponding voltage wave form on a fluorescent screen.
OSI    Open Standards Interconnect.
OTDR    Optical time-domain reflectometry.
Ovality of wire.    A defect in drawing usually caused by wrong positioning of the drawing die holder in relation to the drum.  Care should be taken to see that the axial direction of the bore conforms to the drawing direction of the wire.  May also be caused to some extent by uneven or inadequate lubrication, or by scale which has not been removed completely in the course of pickling.  Casting of wire is also a contributory cause, and where ovality is met with in a finishing die which is also used to cast the wire, it may be mitigated by casting outside the die, either by killing the wire or passing it over a small pulley.
Overlap    The amount the trailing edge laps over the leading edge of a spiral tape wrap.
Oxidation    The process of uniting a compound with oxygen, usually resulting in an unwanted surface degradation of the material or compound.
Oxidation -    The process of uniting a compound with oxygen, usually resulting in an unwanted surface degradation of the material or compound.
Ozone -    Form of oxygen produced by discharge of electricity into air.  Chemical symbol O3.
Ozone Test    Exposure of material to a high concentration of ozone to give an accelerated indication of oxidation in normal environments and in proximity to ozone producing apparatus.
PAC -    Preassembled aerial cable.
Package -                            An object used for accumulating and dispensing wire and cable for further processing or end use.  A few of the more popular types of packages are reels, bobbins, spools, stems, and coils.
Pad.    Name given to the supply disc of paper, fabric tape or metal tape used on paper lapping machines for covering electric cable, laying up machines for binding the insulated cores together, or steel tape armoring machines for the metallic protection of lead covered cables.
Paste Extrude    An extrusion method whereby the extrudable material is in a fine powder form mixed with a lubricant and is forced through a die of given size, without heat, as opposed to melt extrude.
Pay-Off -    The process of feeding a cable or wire from a bobbin, reel, or other packages.  Also a device used for paying out wire or cable into a piece of equipment or machinery.
Pay-off stand.    Used where it is required to unwind wire from a reel, the necessary equipment being included to apply the requisite tensions.
PC    Physical contact.
PCM    Pulse-coded modulation.
PCS    Plastic-clad silica.
Peak Voltage    The maximum instantaneous voltage.

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Peak Voltage -    The maximum instantaneous voltage of an electrical circuit.
Percent Conductivity    The conductivity of a material expressed as a percentage of that of copper.
Percentage reduction.    The reduction in the cross sectional area of a wire after passing through a die expressed as a percentage of the cross-sectional  area of the wire before entering that die.  The specification for a wire may also call for a certain percentage reduction in area during necking down immediately prior to fracture during the tensile test.
Petroleum jelly.    Used as a filler for subscribers' telephone cable (q.v.) to prevent ingress of water, the filling taking place layer by layer as the cable is built up.  Petroleum jelly meets the various requirements for a filing material - compatible with polyethylene insulation; does
not drain at highest cable temperatures; does not become stiff at low temperatures to affect cable flexibility; safe, pleasant and easy to work with; does not materially affect electrical performance of the cable; does not impede jointing; low cost.  Either solid or liquid filling methods may be used.  Solid filling is pumped under pressure from barrels to each die position, making sure that there is always a surplus of jelly which falls into collecting
boxes when it is returned to the suppliers for reconditioning.   This reclamation is avoided by the liquid method which is also claimed to have advantages in handling, storage and control of quantities applied to the cable.  The jelly is delivered and stored at liquid temperature and distributed to each stranding die position at just above its solidifying temperature so that as it is applied to the cable it solidifies and is carried away.
Phase    A particular stage or point of advancement in an electrical cycle.  The fractional part of the
period through which the time has advanced measured from some arbitrary point usually expressed in electrical degrees where 360º represents one cycle.
Phase Shift    A change in phase of a voltage or current after passing through a circuit of cable. Photodetector.    An optoelectronic transducer, such as a pin photodiode or avalanche photodiode. Photodiode    A semiconductor  diode that produces current in response to incident optical power and
used as a detector in fiber optics.
Photon    A quantum of electromagnetic  energy.  A "particle" of light.

Physical contact connector.

A connector designed with a radiused tip to ensure physical contact of the fibers and thereby increase return reflection loss.

Pick    Distance between two adjacent crossover points of braid filaments.  This measurement, in
picks per inch, indicates completeness of coverage (the more per inch, the more complete the coverage).

Picofarad    One micro-microfarad.
Pigtail    A short length of fiber permanently attached to a component, such as a source, detector, or coupler.
Pin    Denoting an electrical terminal, usually in a connector.  Normally a smaller termination than a lug.
Pin photodiode    a photodiode having a large intrinsic layer sandwiched between p-type and n-type layers.
Pistoning    The movement of a fiber axially in and out of a ferrule end, often caused by changes in temperature.
Pitch Diameter    The diameter of a circle passing through the center of the conductors in any layer of a multiconductor  cable.
Pitch Diameter -    The diameter of a circle passing through the center of the conductors in any layer of a multi-conductor  cable.
Pitch.    (1) Distance between the centers of a pair of rolls, when tight against each other with hardly any parting between them.  (2) The distance between the coils of a spring.
Planetary Twister    A twisting machine whose payoff spools are mounted in rotating cradles that hold the axis of the spool in a fixed direction as the spools are revolved about one another so the wire will not kink as it is twisted.
Plastic dicers.    Machines for cutting plastics material in strip form into regularly shaped cubes which ensures that they flow evenly from the hopper into an extruder, and that they are closely packed into the barrel or cylinder of the machine to leave the minimum volume of


intergranule air, so ensuring uniform heating of the plastic material.
Plastic fiber                        An optical fiber having a plastic core and plastic cladding.
Plastic granulators.    Machines for cutting up plastics into granules for feeding into extruders or other machinery for re-use.  See entry on plastic dicers.
Plastic-clad silica fiber     An optical fiber having a glass core and plastic cladding.
Plasticizer                        A chemical agent added in compounding plastics to make them softer and more flexible. Plasticizer -                        A chemical agent added in compounding plastics to make them softer and more flexible. Plating                             The application of one metal over another.
Plating -                               The application of one metal over another.
Plenum    The air space between walls, under structural floors, and above drop ceilings, which can be used to route intrabuilding cabling.
Plenum cable    A cable whose flammability and smoke characteristics allow it to be routed in a plenum area without being enclosed in a conduit.
Plug.    The die inserted into the inside of a tube while it is being drawn to control the bore and wall thickness.  It is so situated and shaped as to induce the metal to flow between its surface and the internal wall of the drawing die which is reducing the overall diameter of the tube.  Plugs are often designed to float in this position by the interaction of the compressing forces involved:  in some cases they are rigidly mounted at the end of a mandrel over which the tube is threaded before drawing.  There are three types: captive, semi-captive and floating.
Pointing.                                   Tapering the end of rod or wire to facilitate threading the wire through the drawing dies.
Pointing machines consist of two rolls which turn round their parallel axes.  The rolls have grooves which elongate the wire into a point when it is inserted between the rolls.  A similar effect is achieved by swaging or reducing machines, in which rotating hammers work the wire into a uniform point.  Electrical machines are also used for pointing wire, which is clamped between two contacts and heated till it is red hot.  By turning a lever, the wire is stretched until it breaks leaving a conical point easily inserted in a die.
Later pointing machines have two sets of rolls, one horizontal, on vertical.  This saves twisting the rod to obtain a satisfactory point.  For large sizes on drawbenches,  it is possible to push point the wire through the die, enabling the reduced end to be gripped by the pulling in dogs.
Polar Ingredient              An ingredient in a material or complex capable of ionization.
Poly -                                   Polyethylene.
Polyamide.                               The same as nylon.
Polychloroprene    Chemical name for Neoprene.  A rubber-like compound used for jacketing where wire and cable will be subject to rough usage, moisture, oil, greases, solvents and chemicals.  May also be used as low insulating material.
Polychloroprene.    A synthetic rubber, characterized by its outstanding ozone and weather resistance, good resistance to oils and solvents, and the fact that it does not support combustion.  This latter property results from the fact that the material contains 35 percent combined chlorine. Insulation and electrical properties are of a lower order than natural rubber and therefore this material is usually only used as a sheath over insulations made from other materials. Main application in the electrical industry is in mining and ships cables where flame resistance is required and for cables where sheaths are likely to be exposed to aging and weathering.  Chemical name for neoprene.

Polychlorotrifluoroethyle ne (P.C.T.F.E.)

A similar material to P.T.F.E., but is a true thermoplastic and can be injection molded.  Its chemical resistance is not quire as outstanding as P.T.F.E. and the temperature limit is lower, but is has higher tensile strength.  Although very suitable for chemically resistant plant, because of its high cost, use is usually limited to gland packings in acid pumps and other small components working in severely corrosive conditions.

Polyethylene    A family of insulating material derived from polymerization of ethylene gas.  They are
basically pure hydrocarbon resins, with excellent dielectric properties.
Polyethylene.    A family of insulating materials derived from the polymerization of ethylene gas.  They


are basically pure hydrocarbon resins, often with small amounts of other additives to impart needed properties.  All members of the polyethylene family are excellent dielectrics.  Electrically they are far superior to any other extrudable solid dielectrics in use today.  Outstanding electrical properties include high insulation resistance, high dielectric strength, low dielectric constant, low dielectric loss at all frequencies, excellent resistance to cold flow, and good abrasion resistance.  One or more members of the
polyethylene family also have the following properties:  resistance to sunlight, weathering, chemicals, flame.  Polyethylene is being widely used for insulation on telephone signal and control cables, high frequency electronic cables, high and low voltage power cables, line wire, neutral supported secondary and service drop cables.  They are suitable for direct earth burial.  Temperature ratings vary with type and application, from 750 deg. C. up.
Polymer    A material having molecules of high molecular weight formed by polymerization of lower
molecular weight molecules.
Polypropylene.    A thermoplastic material whose properties are intermediate between those of polythene and nylon, but substantially cheaper than nylon.  It offers excellent insulating properties for cables combined with a relatively high mechanical strength, and its surface hardness and good abrasion resistance make it suitable for sheathing co-axial and other types of cables.  Widest use is likely to be for moldings where the rich colors in which it is available are of particular value.  It needs to be pigmented with carbon black to protect it against ultra-violet light.  Polypropylene  is very light with a specific gravity of 0.90.  Its melting point is 165 deg. C., and it is suitable for many applications at or above 100 deg. C.  Has been used for construction and lining of chemical plant and offers much promise for use in pickling plant.  It has been used for example for a large bore pipeline to carry waste acid effluent a distance of 3 1/2 km. from a wire mill.
Polystyrene.    An acid and grease resistant plastic with good insulating properties.

Polytetrafluoroethylene
(P.T.F.E.)

A plastic material used for insulation of cables and wires which has very low dielectric loss and great resistance to heat.  It will operate a temperatures of up to 240 deg. C. and remains flexible down to very low temperatures.  It is non-inflammable  and is completely unaffected by oils, fuels and solvents.  The material also possesses low permittivity and power factor, together with very high insulation resistance.
Its properties are also very suitable for chemical resistant plant, but because of high cost, use is usually limited to gland packings in acid pumps and other small components working in severely corrosive conditions.
Use as a coating for wirework is limited to applications where its non-stick and release properties are important, as on fish and chip frying units for ease of cleaning and on filter mesh to improve the flow through the filter.

Polythene.    A thermoplastic which is a pure synthetic hydrocarbon  having excellent electrical characteristics which make it very suitable as an insulating material for practically every type of cable.  Produced by the direct polymerization of ethylene.  Has good abrasion resistance, but a tendency to cutting by a sharp edge; it has fair flexibility, though it tends to be stiff in thicker sections.  It is unaffected by fresh of salt water, and dilute acids and alkalis, but slowly oxidizes in the presence of air and ultra-violet light unless precautions
are taken against this.  It is widely used in the cable trade, where its principal application is as an insulant, though it is frequently also used for sheathing.  Addition of a plasticizer
such as butyl rubber is necessary to prevent cracking and an anit-oxidant to counter the tendency to oxidation at the higher temperatures necessary for extrusion.  See entry for plastic insulation.
The original low density (L.D.) polythene has a tensile strength of 105 to 154 kg./cm. squared, and a softening point of 66 to 86 deg. C. while high density (H.D.) polythene has a tensile strength of 189 to 294 kg./cm. square and a softening point of 110 to 122 deg. C.
Both forms are used for coating wirework and other metal goods, articles so coated being resistant to rust, detergents and abrasion, while the polythene surfaces are resilient to a varying degree.  See entry for plastic coating of wirework.  The usual method is to


preheat the metal at temperatures up to 300 deg. C. depending on size of the object and thickness of coating required and then to dip the metal into a bath of polythene powder which is fluidized by a flow of air through the powder.  The powder in contact with the metal fuses to the surface and a coating of 0.25 to 3.2 mm. thick is formed, according to
the preheat temperature.  The coated object is removed from the fluid bed while still hot so
that the surface of the coating can completely fuse and give a smooth glossy finish.
Polyurethane.    Enamel that has excellent moisture resistance, easily soldered, also has excellent winding properties as a magnet wire insulation.
Polyvinyl chloride.    A synthetic polymer produced by the combination of acetylene and hydrochloride acid.
Widely known as P.V.C.  The basic polymer is a hard white infusible substance which can only be rendered thermoplastic by the addition of plasticizers.  By varying the nature and quantity of the plasticizer, a wide range of properties to suit a particular use can be obtained.  Has very god abrasion resistance, particularly in the softer cable-sheathing grades, and good flexibility, particularly the softer compounds.  It is unaffected by fresh or salt water, dilute acids and akalis, oils and petrol.  It is flame retardant, since it does not continue to burn when the source of heat is removed.  Has a somewhat low insulation resistance when compared with vulcanized rubber or with the very high resistance of polythene, but it is sufficient for practical purposes in cable manufacture.  It is therefore widely used as an insulant at a power frequencies and low or medium voltages.  Flexible cords may be composed of either two insulated cores twisted together without any further coverings, or two, three or four cores twisted together with textile wormings and strengthening cords, sheathed overall with P.V.C.
Neither rigid nor plasticized P.V.C. are suitable for tank and fume extraction work on their own, but plasticized P.V.C. can be cemented to a steel tank, or a laminate of rigid and plasticized P.V.C. can be used in this way to combine the properties of both.  Many tanks are now made from stout P.V.C. with external P.V.C. reinforcements,  from P.V.C. laminates incorporating expanded metal reinforcements or from thin P.V.C. sheets with external cladding of reinforced plastic.
High impact P.V.C. is not brittle like rigid P.V.C., yet retains appreciable hardness and stiffness.  Its impact strength is 15 times that of rigid P.V.C. and softening point 70 to 80 deg. C., the tensile strength of 420 kg./cm square. being not far below that of rigid P.V.C. High impact P.V.C. is particularly suitable for pipework.
Because of the wide range of hardnesses available from soft and rubbery to extremely hard, its uses for coating wirework are very varied.  Can be applied as a liquid or as a powder, the fluidized bed coatings being generally harder than the liquid coatings and having superior cut resistance and abrasion resistance compared with polythene. Therefore used where polythene is inadequate, for example on display wirework particularly for outdoor use.  With a suitable plasticizer, oil resistant and low temperature flexibility grades are obtained.
Post-heating.    A heating operation applied to welds as soon as possible after welding for the purpose of relieving stresses, and of tempering the weld metal and the heat affected zone.
Post-stressing.    A method of strengthening concrete by stressing after it has been cast.  Ducts are first placed in position before casting, through which wires or stands can later be introduced. Recent developments of unbonded tendons can eliminate conventional ducts by using a greased strand in a plastic tube, these being placed in position before casting.
After the concrete is cured the wires or strands are stressed to a predetermined figure, usually 70-80 percent of the braking load which introduces sufficient compressive stresses in the concrete to withstand the design loads.
Where ducts are used it is usual to introduce grout afterwards to prevent ingress of
water and to provide a better load distribution.
Potting    The sealing of a cable termination or other component with a liquid, which thermosets into an elastomer or solid compound to exclude moisture.
Power Cable -    A cable of various sizes, various construction and insulation.  Used to supply power to a


variety of types of equipment.
Power Factor    The ratio of the power to the effective values of the electromotive force multiplied by the effective value of current in volts and amperes respectively.  The cosine of the angle between voltage applied and the current resulting.
Pre-drawer.    A drawing unit synchronized with a cold header to draw rod to close tolerance and feed it to the header.  Permits lower rod stocks and claimed to give cleaner products, increased tool life and higher tensile strength because the wire is fed warm to the production machine.
Pre-impregnated  cable.    A paper insulated cable in which the paper tapes are impregnated before application and not subsequently impregnated.
Preformed wire rope.    Wire rope whose strands are permanently shaped to the form they assume in the finished rope, before the rope is fabricated.
Pressurized cable.    A cable in which the dielectric is maintained at a pressure in excess of atmospheric pressure to combat the effect of ionization of gas in voids (See "Solid cables").  There are two types - one in which thin oil under pressure completely fills the dielectric under all conditions of load, and the other in which gas at high pressure prevents ionization in voids. The sheaths of most pressurized cables have to be reinforced to prevent undue distension. the amount of reinforcement depends on the operating pressure.  A single helix of hard- drawn copper or copper alloy tape is usually sufficient for low pressure oil-filled cable.

Prestressed concrete strand.

Enables a greater force to be applied with fewer stressing operations and therefore saves time on the site where costs are higher than in a factory.  The strand consists of a straight core wire around which arranged one or more layers of wires formed into helices by means of a die.  All helical wires are laid in the same direction and have the same pitch.  If a second layer of helical wires is added, they will have the same pitch as the first layer, although the helix angle of the two layers will be different.  This formation is desirable for use in prestressed concrete construction where the tendon may have to withstand large transverse forces, and remain undistorted.  The pitch or lay length of the outer helical
wires is normally between twelve and sixteen times the diameter of the strand.  During stressing, these outer wires are subjected to a combination of tension, torsion and bending, the bending stresses being greater in a strand with a smaller pitch.  For this reason the breaking stress of a long lay strand is rather higher than that of a strand with a shorter lay.
The 7-wire strand is available in sizes up to 15 mm. dia. which will provide a
prestressing force of about 170 kN.  Over this size the individual wires would become so large that the resulting strand would become inflexible and so 19-wire construction is more commonly used.  Up to 19 mm. dia. a Seale construction is used, which consists of an
inner layer of nine small helical wires laid on a straight core wire and an outer layer of
nine larger helical wires laid on top.  Such a strand would give a prestressing force of about 300 kN.  Over 19 mm. dia., strand is usually made in Warrington Seale construction to give more flexibility.  28 mm. dia. strands are produced in this construction, the latter giving a prestressing force of about 580 kN.
For a given overall diameter, strand is much more flexible than wire because the radius around which is may be bent without plastic deformation depends on the diameter of the largest component wire used, rather than the overall diameter of the strand.  Due to the external shape, it has a much better bond with concrete.  The transfer length of 18 mm.
dia. strand is similar to that of a plain 5 mm. dia. wire, even though the prestressing force
is over ten times greater.
Most 7-wire strand is produced on six or seven bobbin tubular machines that run at speeds up to 500 r.p.m., although machines capable of 7,000 r.p.m. are now being designed. 19-wire strand is made on large planetary machines which in general produce at a rather lower rate than the 7-wire tubular machines.  The running speeds are considerably slower, but this is partially offset by the increased number of wires used.  During
stranding, the helical wires are bent around the core wire and as a right cross-section of the strand is an oblique section of the helicals, the sections of the helicals are elliptical.  In













Prestressed concrete wire.

order to allow for the increased lateral dimensions of the helical wires, they are made some
3 percent less in diameter than the core wire; this avoids "tubing" of the outer layer.
The mechanical properties of strand are slightly inferior to the aggregate of the same wires before stranding; however, strand responds equally well to the heat treatments described  for wire.  Due to practical difficulties strand over 19 mm. dia. is not usually subjected to a low temperature strain aging treatment and so the stress strain curve is non- elastic.  Up to 19 mm. dia. strands can be heat treated without difficulty and the stress strain characteristics are closer to those of wire, although the relaxation losses are considerably higher.  See also entry for Stabilized wire and strand and also the previous entry for prestressed concrete wire.
The British Standard for this wire specifies the following composition:  carbon 0.60 to
0.90 percent, silicon 0.10 to 0.35 percent, manganese 0.50 to 0.90 percent, and sulphur and phosphorus 0.050 percent maximum for each.  Hot rolled rods are patented in carefully controlled conditions, pickled with precautions against hydrogen absorption, washed, coated with zinc phosphate or lime and then with lime, borax or sodium metasilicate.  Drawing methods vary widely depending on chemical composition and type of drawing equipment available.  It is important to avoid variations in physical properties
of the wire which may occur through uneven temperatures in the lead bath or through a fall in temperature if drawing machines are stopped and re-started; the prestressed concrete product maker usually applies a fixed extension to the wire calculated to give the required tension and variations in the wire used will create differences in the compressive stresses
in the concrete, although these variations tend to cancel out due to using wires from different coils in the same member.  To reduce this disparity and improve the properties, a considerable proportion of wire is given a low temperature heat treatment, usually 300-350 deg. C. but quite often up to 400 deg. C., to increase the elastic limit, proof stresses and elongation at fracture; residual compressive stresses at the center of the wire and residual tensile stresses at the surface are redistributed by this process to give increased ductility.
For post tensioning work, large diameter coils from which the wire pays out straight are obtained by passing the wire mill coils through a spinner straightener at 6 to 45 m./min., depending on wire diameter, and then through a stress relieving furnace or lead bath which heats the wire to 300 to 400 deg. C.  It is subsequently quenched in water and
wound into coils of between 1.2 and 2.4 m. dia. to avoid physical bending of the wire.  See
also entry for Stabilized wire and strand.
Where bond is a critical factor as in short beams or railway sleepers, lubricants have to be removed from the wires by cracking the soap in an acid bath, followed by a degreasing treatment, usually based on a caustic alkali with various additions.  After washing, a light rust is allowed to form, said to increase the bonding efficiency.
The bond can be further improved by mechanically deforming the wire in a number of
ways.  One is to indent the wire by passing it between indenting rolls.  Some objections have been raised to the indents acting as local stress raisers and affecting the fatigue properties.  They are therefore kept small to avoid any deleterious effect and consequently the benefit to be gained from extra bond is generally considered to be small also.
Another method of improving bond is by crimping or preferably helically crimping.
The former involves crimping in one plane while in the latter, as its name suggests, the wire is crimped in an elongated helix.  It has been shown that the transfer length (the length of wire needed to transmit full compression to concrete by means of the frictional effect between steel and concrete) of a 5 mm. dia. wire with a helical crimp is only 60 percent of that of a plain 5 mm. dia. wire.  This is achieved without any notching of the surface of the wire as in indenting.  Shorter transfer lengths can be achieved by using a
higher cube strength concrete, and this also reduces the differences between plain, crimped and indented wires.

Prestressed concrete.    During the process of manufacture the high tensile steel tendons are subjected to a tensile stress which in turn introduces compressive stress in the concrete.


Prestressing a wire rope.    Stressing a wire rope or strand before use under such a tension and for such a time that the constructional stretch is largely removed.
Prestressing.    A process during which internal stresses are induced into a spring which have the effect of increasing the apparent elastic limit of the material.  It is achieved by subjecting the spring to a stress greater than that to which it is subjected under working conditions and higher than the elastic limit of the material.  The plastically deformed areas resulting from this stress cause an advantageous redistribution of the stresses within the spring.  Since stress is a vector quantity, advantage from prestressing can only be obtained from springs which
are loaded so that the algebraic sum of the prestress and the applied stress is less than the applied stress.
Primary Insulation    The layer of material which is designed to do the electrical insulating, usually the first
layer of material applied over the conductor.
Primary Insulation -    The layer of material which is designed to do the electrical insulating, usually the first layer of material applied over the conductor.

Process annealing.    To remove the effects of cold working and so permit further cold working, wire is process annealed by heating it, usually to a temperature below the transformation range.

Profile wire rolling equipment.

A frame holding four (sometimes three) undriven rollers between which wire is drawn for production of square, rectangular and a wide variety of special shapes.

Profilometer.    An instrument for determining the profile of the bore of wire drawing dies.  It consists of a feeler arm reflecting any movement of the feeler which can then be translated into the required outline of the die profile.  The Profilometer is a highly accurate research tool, which is accurate to 0.0025 mm., and intended for laboratory use.  For use in the die shop, the Profiloscope has been developed.
Propagation Constant    A complex quantity characteristic of a radio frequency transmission line which indicate the
effect of the line on the transmitted wave.  The real part indicates the attenuation and the imaginary part of the phase shift.
Properzi process.    A process by which aluminum rod is continuously cast and rolled directly from the molten metal in well under two minutes, completely eliminating conventional pre-heating and billet casting.  A furnace, a casting machine and a rod mill form the three basic pieces of equipment.  The furnace feeds a continuous stream of molten aluminum at controlled temperatures into a rim cavity of triangular cross-section on the rotating wheel of the casting machine.  An endless steel belt covers the wheel through an arc of 180 deg. and when the belt comes in contact with the wheel a cavity is formed into which molten aluminum is poured.  As the wheel rotates the resultant material emerges as a solid bar of
as much as 11.5 cm. 2 cross-section depending on the model used and is introduced into
the 13-stand rolling mill to produce a 9.5 mm. dia. rod.  Larger rod can be obtained by omitting some of the stands.  As further experience is gained with direct cooling of the casting wheel, employment of the process for the more complex alloys of aluminum and zinc seems likely to develop, and casting of some grades of steel, including stainless and nickel based alloys, may also be possible.
A process similar to the Properzi process has also been developed in the U.S.A. for the continuous casting of copper wire rod.  At one plant a continuous strand of 16 cm2 cross- section is produced on the casting machine with adjustable cooling sprays to ensure that
the cast rod is at correct temperature to pass continuously to a seventeen strand hot rolling mill which reduces it to 6.35 mm. dia.  Advantages claimed include: coil weights limited only by furnace and handling facilities - 4,530 kg. coils have been regularly produced; the rod is more homogeneous and has fewer inclusions than rolled rod; the extremely small amount of scale necessitates only brief pickling; the plant area is comparatively small and both capital investment and labor requirements are greatly reduced.


2


Protective atmosphere.    Necessary in a bright annealing unit to preserve the bright surface of the wire.  For copper or brass a neutral or slightly reducing atmosphere is necessary; for ferrous material, a reducing atmosphere free from moisture is required.  Under normal production conditions, the most unusual mixture of gases found in furnace atmospheres contains  CO, H2, CO2
and H2O, together with N2.  The seven gases used as atmospheres and their effects on steel
are: N2 (bone-dry molecular nitrogen) is neutral, with no oxidation or carbon potential;
O2 (oxygen) reacts with iron to form iron oxide and combines with carbon in steel forming CO or CO2; causing decarburisation;  H2 (bone-dry hydrogen) is strongly reducing and reduces any oxide to iron but is slightly decarburising; CO (carbon monoxide) is an important heat treatment gas having a carburising effect at elevated temperatures, and it also reduces any oxides; CO2 (carbon dioxide) decarburises and oxidizes iron at elevated temperatures; CH4 (methane) is strongly carburizing and also reduces any iron oxide at elevated temperatures; H2O (water vapor) decarburises and oxidizes iron at elevated temperatures.
For carbon control, as when heating to austenitising temperature and above, endothermic is the main control atmosphere.  For material treated in or below the transformation range, low carbon potential mixtures of endothermic and exothermic are used.  For subcritical annealing nitrogen atmosphere is usual for safety reasons; this usually has slight decarburising tendencies, and is normally enriched with small quantities of endothermic.  Where combustible mixtures are used below safe ignition temperatures, automatic inert gas purge systems are usually installed.  Mixed atmospheres permit a wide materials range through the same furnace; the range of carbon potential required can vary quite considerably.
Apart from the relatively expensive atmospheres derived from ammonia, the more common ones are obtained from gas.  In some cases this may be used direct from the mains, but normally it is mixed with air and partially burnt in the combustion chamber of an exothermic plant.  These plants can be connected in series with an automatic regenerative dryer for certain processes, this being normally dependent upon the particular analysis of the charge being processed.  The addition of a drying plant is particularly
useful where decarburisation  has to be minimized.  A further type of atmosphere is obtained from an endothermic plant in which a mixture of gas and air is heated and cracked in the presence of a catalyst.  The heat is applied externally around containers through which passes the gas/air mixture.  Atmosphere generators are available which do not involve a catalyst and which are insensitive to changes of feed gas.  The atmosphere is highly reducing and suitable for bright heat treatment, while removal of carbon dioxide and water vapor in a scrubber provide a suitable carrier gas for such operations as
carburising.  Since the same design of generator can produce a slightly reducing or slightly oxidizing atmosphere this one basic design supplies the whole range of atmospheres made from fuel gases without the need for an elaborate control system.
Prototype -    Original design or first operating model.
Proximity Effect -    The phenomena of nonuniform current distribution over the cross-section of a conductor caused by the variation of the current in an adjoining conductor.
PSI -    Pound per square inch.
Pulling-in machine.    Used for threading up rods or heavy wires in a wire drawing machine; frequently
combined with a pointing machine.  Used chiefly on nonferrous tandem machines enabling a number of dies to be threaded up in sequence for easy threading of the machine.
Pulse Cable    A cable specifically constructed to withstand and transmit repeated high voltage pules
without undue physical or electrical degradation.
Pulse spreading    The dispersion of an optical signal with time as it propagate through an optical fiber.

Pulse-coded modulation

A technique in which an analog signal, such as a voice, is converted into a digital signal by sampling the signal's amplitude and expressing the different amplitudes as a binary number.  The sampling rate must be twice the highest frequency in the signal.

Push Back    That property of a braid or shield which allows the braid or shield to be pushed back along


the cable core easily.
Put-Up -    Refers to packaging of wire and cable, the term itself refers to the packaged product that is ready to be stored or shipped out.
PVC -    Polyvinyl Chloride.
Quad-Rated Wire    ITT name for 90ºC and 105ºC wire which replaces four other types of wire - CSA TEW
105ºC; 90ºC MTW 600V; 90ºC AWM 1000V; and 105ºC AWM 600 V.
Quad/Quadding.    An assembly of four separately insulated conductors.  May be either a multiple-twin quad in which two twisted pairs are twisted together or a star quad in which four wires are twisted about a common axis.  A cable containing a number of units each consisting of four twisted pairs about a common axis is known as a quad-pair cable.
Quadruplex Cable -    A cable composed of four conductors twisted together, usually three insulated and a bare neutral.
Quantum efficiency    In a photodiode, the ratio of primary carriers (electron-hole pairs) created to incident photons.  A quantum efficiency of 70% means 7 out of 10 incident photons create a carrier.
Quench aging.    Aging which follows rapid cooling.
Quenching.    The rapid cooling of a heated metal through its transformation range, usually by immersing it in a liquid such as oil, water, molten salt or lead.  Quenching is an integral part of all processes for the hardening of steel.  It is essential that the cooling medium be controlled at a specified temperature and the material be immersed until it has attained the quench temperature throughout its mass.
The rate at which heat is extracted from a rod during quenching is governed by rod size, thermal conductivity of the material, type and thickness of scale on the rod, temperature difference between rod and quench medium, and the heat-transfer coefficient at the interface between the steel and the quench medium.  For wires of 5.5 mm. and less, conventional lead patenting installations achieve the desired results, but for heavier gauges, cooling rates in static or near-static quench baths are slow to produce an isothermal transformation at the optimum temperature.  Nevertheless, the process is still used in commercial practice.
Double cascade quenching (DCQ).  After austenitising the rod is prequenched in a salt bath at a temperature just over the Ms point (29°C.).  It is then transformed in a second
salt bath at a temperature around 510°C., both baths being in tandem.  Approximate isothermal transformation is said to take place, providing a fine even structure and, consequently, high tensile strength, higher ductility for a given strength and improved fatigue properties.
Rated Voltage    That maximum voltage at which an electrical component can operate for extended periods
without undue degradation or safety hazard.
Rayleigh scattering    The scattering of light that results from small inhomogeneities  in material density or composition.
Reactance    That part of the impedance of an alternating current circuit which is due to capacitance or inductance.
Recrystallization.    The change in crystal size and structure which occurs in a cold worked metal when it is heated to a specific temperature, known as the recrystalization  temperature of that metal, or for a longer period at a lower temperature.  When the change is complete, the metal has lost all the improvement of mechanical properties that were confered on it by the cold work.

Redraw -    The consecutive drawing of wire through a series of dies to reach a desired wire size.

Reducing atmosphere.    An atmosphere which reacts with oxygen, particularly on heating, and so is used to extract oxygen from the charge in a furnace.

Reel -    A revolvable flanged device made of wood and/or metal which is used for winding flexible


metal wire or cable.
Reels.    There is an enormous number of different types and sizes or reels, due to different
methods used by individual manufacturers.   A brief description of the main types and their standard sizes are given below.  Reels, of course, used for many purposes other than those described; some of the other purposes for which specially designed reels are available, being: vulcanizing, enameling, tinning and bunching.
Braiding reels.  Ideal reels for this purpose have beaded edge flanges, which should be made from a tough steel (approx. 55 kg./mm②   tensile strength).   These reels are naturally of lighter construction than those required for wire drawing and stranding, etc.  Friction rings can be fitted, but in many cases these are attached to the machines.  This type of reel
is also suitable for general shop use and in some cases for longitudinal machines.  Flange diameters of standard sizes are as follows: 150, 300, 400, 600, 750, 900 and 1,000 mm.
Closer reels.  See entry in this section under "Laying up reels."
Collapsible reels.  Reels specially constructed so that the flanges can be easily removed, so making a considerable saving in space for transport and storage.
Laying reels.  Stationary reels used for taking up hot wire rod after rolling, the rod being distributed into a coil by a revolving delivery pipe or by a delivery pipe ending in an arc which causes the rod to coil by starting it on a circular path.  Not suitable for sizes above about 9.5 mm. dia., because the rod is given a twist as each ring of the coil is formed.  Accepts rod at high speed because the coil is stationary.  See also entry under this heading for pouring type reels.
Laying up reels.  These are usually of large dimensions to hold a good capacity of cable or strand, and the design is similar to closer reels used in the wire rope trade.  Reels for these purposes should have saw blade steel flanges in the smaller sizes, and tough steel flanges in the larger ones.  They are usually fitted with friction rings, and are of very
strong construction.  Flange diameters of standard sizes are  600, 750, 900, 1,000,
1,200, 1,400, 1,500, and 1,800 mm.
Plastic reels.  Suitable for taking up from fine or very fine wire-drawing machines, where the product is required in its hard drawn state as for enameling.  Advantages claimed are: price, freedom from crevices, low weight consistent with a god flange barrel ratio resulting in low spool shaft r.p.m. and corresponding lower flier take off revolutions;
greater accuracy over the traverse; and damaged reels will be easily identified.  Toughened polystyrene is a suitable plastic material for this purpose except that certain lubricants can cause serious cracking under stress, while other lubricants are virtually innocuous.

Pouring type reels.  Consist of a horizontal disc revolving at the delivery speed of the rod to be reeled, the rod being guided into position by pins as it pours from the end of a delivery pipe.  Maximum speed about 1,200 m./min., but will accept heavy diameters of rod or non-circular sections without twisting them.  See also entry under this heading for laying reels.
Stranding and armoring reels.  These reels are often designed so that they are also suitable for wire drawing and annealing (see "Wire-drawing reels").  They must be of very strong and rigid construction to stand up to modern high speed working conditions.  This type of reel is nearly always made complete with a friction ring, which for most up-to-date practice should be made from steel.  Flange diameters of standard sizes are as follows:
160, 230, 320, 360, 380, 400, 450 and 600 mm.
Tilting reels.  Conventional reels to the bases of which are fastened a counter balance weight, the whole mounted on a spindle on the fixed base.  The empty reel is tilted and locked in position.  The coil having been placed on the reel, the locking latch is removed, and the balancing weight lifts the reel with the coil to an upright position.
Reels for water immersion.  To test the insulation qualities of certain types of cable, reels full of cable are totally immersed in water and a current is passed through the cable and any weaknesses in insulation can be very quickly shown up.  Reels for this application


must have some form of corrosion resistance; reels in aluminum alloy or in steel with the beaded edge type of flange (the same type as used for braiding purposes - see "Braiding reels"), and the whole of the reel galvanized, zinc sprayed of stove enameled, are ideal for this particular application.  Standard sizes appear to be in the region of 400 to 600 mm. flange diameters.
Wire-drawing  reels.  For the drawing of the finer gauges of wire at high speeds, solid type all-steel reels, which are machined all over an therefore run dead true, are normally used.  These reels are made from a steel which is exactly suitable for annealing purposes, so that the wire may be annealed on the reels if required.  Flange diameters and approximate capacities of standard sizes are as follows:  135 mm. (2.5 kg.); 135 mm. (4 kg.); 155 m.. (10 kg.); and 235 mm. (27 kg.).
For the drawing of heavier gauges of wire, the reel are often made so that they are suitable for annealing on, and will also fit the stranding machines, thereby saving rewinding.  Modern practice for the design of this type of reel is to use saw blade steel
flanges (tensile strength 100 Kg./mm2  ) and friction rings made from steel forgings.
Flange diameters and approximate capacities of standard sizes are as follows: 320 mm. (45 kg.); 380 mm. (90 kg.); 400 mm. (115 kg); 460 mm. (135 kg.); 560 mm. (230 kg.); 600 mm. (450 kg.); 760 mm. (680 kg.); 900 mm. (900 kg.).  (Note: The capacities given above relate to average winding with copper wire.).
Length of wire on reels.  The length of wire in meters on a reel can be calculated by the following formula (bearing in mind that the stiffness of the wire causes some variation):

WπN/2,000  (B ⋅ d) ⋅ (B ⋅ 2Nd d)  + 10%
where W    number of helices laid across the reel approximate traverse of reel (or width between flanges) in mm., divided by wire diameter in mm. and corrected to the next lowest whole number
B     barrel diameter in mm. d    wire diameter in mm.
N    maximum number of layers of wire on the reel
od. (D-B) where D  diameter of reel flanges in mm.

The use of an automatic wire winding machine with an accurate lay mechanism capable of precise setting is essential if reels are to efficiently wound.  However, it is possible with a machine to wind much less than the maximum quantity of wire on to a reel.  This will occur where a machine of fixed lay is used for winding wire of a diameter considerably
less than the available winding lay or pitch, i.e. the wire helices are much more than one
diameter pitch.  A similar condition arises on a variable lay machine if the lay setting is too great.  Makers of fixed lay machines will state the lay available, and variable lay machines are provided with a chart giving instructions whereby any lay within its range may be obtained.
Reflection Loss    That part of a signal which is lost due to reflection of power at a line discontinuity.
Regenerative repeater    A repeater designed for digital transmission that both amplifies and reshapes the signal.
Reinforced Sheath    The outermost covering of a cable that h as a cable sheath constructed in layers with a reinforcing material, usually a braided fiber, molded in place between layers.
Reinforced Sheath -    The outmost covering of a cable that has a cable sheath constructed in layers with the addition of a reinforcing material, usually a braided fiber, molded in place between layers.
Repeater    A device that receives, amplifies (and perhaps reshapes), and retransmits a signal.  It is used to boost signal levels when the distance between repeaters is so great that the received signal would otherwise be too attenuated to be properly received.


Resilient -    The property of a substance to return to its original  configuration after release of an applied force.
Resin.    A solid or semi-solid organic substance, originally of plant origin but largely synthesized now.  It may be clear, yellowish or brown, ranging from transparent to translucent, typically a non-conductor  of electricity and soluble in organic solvents, but not in water. Consequently resins are widely used in insulating potting and encapsulating.   Resins are broadly classified as thermoplastic or thermosetting or according to whether they soften or harden with the application of heat.
Resistance    The property of an electric circuit which determines for a given current the rate at which
electric energy is converted into heat and has a value such that the current squared multiplied by the resistance give the power converted.
Resistance -    The property of an electric circuit which determines, for a given current, the rate at which electric energy is converted into heat and has a value such that the current squared, multiplied by the resistance gives the power converted.
Resistance wire.    Wire suitable for use as electrical heating wire because of its electrical heating wire because of its electrical resistance and resistance to oxidation at high temperatures.  Most commonly used are nickel-chromium  alloys, such as the nickel-chrome  80-20 or 60-15 quality.  Drawn to various fine sizes.  Also produced in nickel silver.
Resistance.    The property of a conductor by which energy is expended in it when a current flows or a transfer of electricity takes place.  The resistance of a conductor remains constant under constant physical conditions and can be obtained by the formula R    pL/A ohms, where p is the resistivity or specific resistance, and L and A are the mean values of the length and cross-section of the conductor in cm.
Resistive Conductor -    A conductor used for its high electric resistance characteristics.
Responsivity    The ratio of a photodector's electrical output to its optical input in amperes/watt. Return reflection    Reflected optical energy that propagates backward to the source in an optical fiber. Return reflection loss    The attenuation of reflected light; high return loss is desirable, especially in single-mode
fibers.
Reverse bend test.    Also known simply as the bend test (q.v.).  A test of ductility of wire, carried out by holding the wire at one end and repeatedly bending it in reverse directions through 90 deg. at each bend.
Reverse torsion test.    A test applied to wire in which the test piece is twisted axially first in one direction and then in the opposite direction for a specified number of turns.  Fracture should not occur and no surface defects become visible.
RH -    Rubber insulated, heat-resistance cable, 75øC dry locations, now allowed to be cross- linked polyethylene insulated.
RHH -    Rubber insulated, heat-resistant cable, 90øC dry locations, now allowed to be cross-linked polyethylene insulated.
RHW -    Rubber insulated, heat and moisture resistant, 75øC dry and wet locations, now allowed to be cross-linked polyethylene insulated.
Ribbon Cable    A cable consisting of two or more conductors laid parallel in one plane and held in place some means.

Ribbon Cable -    A cable consisting of two or more conductors laid parallel in one plane and held in place by the insulation or some other means.
Ring network    A network topology in which terminals are connected in a point-to-point serial fashion in an unbroken circular configuration.
Rise time    The time required for the leading edge of a pulse to rise from 10% to 90% of its amplitude; the time required for a component to produce such a result.  "Turn-on time." Sometimes measured between the 20% and 805 points.
Rockwell hardness test.    A test to determine hardness by measuring on a dial the depth of the impression caused by an indentor in the form of either a diamond cone or a hardened steel ball (See B.S. 891).
Rod -    The solid round metallic form of copper and aluminum which is the most effective shape

from which to draw wire.
Rod.    The semi-finished coiled product from which wire is made.  See entries under wire rod.
Roller die.                                Equipment very similar to a turks head but designed to replace conventional die boxes in drawing round rather than shaped wire.  See under entries for die types for more detailed description.
Romex    Non-Metallic Sheath Cable.
Romex -    Nonmetallic sheath cable.
Root Mean Square    The effective value of an alternating periodic voltage or current.
Rope lay strand.    A conductor made of multiple groups of filaments.  A 7 + 19 rope lay strand has 19 wires laid into a group and then 7 such groups laid cabled into a conductor.
Rope Strand    A conductor composed of a center group of twisted strands surrounded by one or more layers of similar groups of twisted strands.
Rope wire.    Produced in various qualities and tensiles from mild steel to 0.89 percent carbon, dependent on the type of rope and service.  In carbons from 0.45 percent upwards, it is, in general, produced from basic material.  Steel wire for ropes is specified in B.S. 2763, which deals with: bright wire; drawn galvanized wire with the same tolerances on diameter and torsion and bend values as for bright wire; and galvanized wire which carries a weight of coat in accordance with B.S. 443, and for which requirements as to tolerances, torsion and bend values are less stringent.  It is specified that rope wire shall be drawn from steel made by the acid or basic open hearth or electric process with neither sulphur nor phosphorus content greater than 0.050 percent.  Details are given of methods of testing
and test requirements for tensile, torsion, 180 deg. reverse bend and wrap tests and for tolerances on diameter.
Rope-Lay Cable -    A concentric stranded cable designed for flexibility with its individual members made up of strands which are either concentric stranded or bunched.
Rope.    Types of wire rope are described under the entries for wire rope.  For rope specifications, see list of British Standard Specifications.
Rotolay.    A type of stationary coiling block in which the axis of the block is vertical, the wire being discharged vertically downward with the coils always in a horizontal plane.  The wire is led through the center of the block to the underside and then taken out to the block surface
over a distributor arm which with each revolution lays one turn of wire on to the block and allows one turn to drop from the block on to a stationary former or container placed underneath.
Round Wire    A wire circular in cross section as opposed to flat, square, etc.
RPM -    Revolutions per minute.
RTS -    Reverse twist secondary.
Rubber insulation.    Used for power cables of up to 1kV and usually applied by extruding the rubber around the conductor.  Another method is to pass the conductor sandwiched between two rubber tapes through grooved rollers which pressure-weld the rubber to form an insulating layer. The longitudinal machine used to carry out this process has tow or three sets of rollers in series to apply layers of rubber to a number of conductors simultaneously.   A third method is to wrap or lap rubber tape round the conductor.  Whichever method is used the rubber is applied in an unvulcanized condition.  It is sometimes vulcanized immediately after extrusion by passing the cable through steam-heated tubes, the process being known as continuous vulcanizing (C.V.); otherwise it is extruded and coiled in pans containing fine talc and subsequently vulcanized in special ovens  the procedure used for rubber applied be either of the other two methods.
RUH -    Latex rubber insulated, 75øC dry location.
Running out.    Increase in wire size during drawing, due to excessive wear of the die.
Rupture    In the breaking strength or tensile strength tests the point at which a material physically comes apart as opposed to yield strength, elongation, etc.
Rupture -    That point at which a material exceeds its elastic limit and physically comes apart as opposed to yield strength, elongation, etc.


RUW -    Latex rubber insulated, 60øC dry and wet locations.
SA -    Silicone asbestos insulated, 90øC dry location, 125øC special application.
Sag (conductor) -    The vertical distance between a suspended conductor and an imaginary straightline connecting the points of suspension.  Sag may be measured at the mid point between the suspensions, the lowest point of the conductor or at any specified point.
SBR -    Synthetic Butyl Rubber.
SCR -    Southwire Continuous Rod.
Screen wire.    Screen cloth wire is a fine low carbon steel wire, bright, tinned or galvanized for the manufacture of filters, sieves, etc.  Sizes and composition vary according to the needs of the end product.  Also in stainless steel or nonferrous metals.  See also "Insect Screen wire". Heavy screen wire is produced from high carbon and stainless steel wires for the fabrication of coarse screens which require very severe deformation in the crimping operations.  Small sizes of wire are usually .40 to .60 percent carbon steel and are hard drawn to finished size.  Larger sizes are usually .50 to .75 percent carbon steel and are patented at finished size.  If over about 10 mm., may be annealed at finished size.
Screened cable.    As used for electricity supply.  A multicore cable in which the insulation of each conductor is separately enclosed in a conducting film in order to ensure a radial electric field surrounding the conductor, the films being in electrical connection with one another and with the metallic sheath of the cable, and usually earthed.  In the Hochstader or H type each core is fully insulated and provided with a layer of metal tape of metallized paper.  A copper-woven fabric tape is applied over the laid-up cores to ensure contact between the core screens and the lead sheath.  In the H.S.L. type the individual cores are lead sheathed.
Screw Extruder -    A machine which accepts solid particles (pellet or powder) or liquid (molten) feed; melts and conveys it through a surrounding barrell by means of a rotating screw and pumps it, under pressure, through a die.
SD -    Service Drop Cable.
SDC -    Self Damping Conductors.
SEA -    Service Entrance Cable (type SE, style U).  (Armored).
Seale.    A strand construction having one size of cover wires with the same number of another size of wires in the inner layer and each layer having the same length and direction of lay.
Most common construction is one center wire, nine inner wires and nine cover wires.
Sector Cable -                    A multicore cable in which the cross section of each conductor is substantially a section of a circle, an ellipse (oval), or a figure intermediate between them; when cabled, contributes to a smaller overall diameter.
Sector strand.    A group of wires laid in triangular shape with rounded corners, for use as one conductor of a three conductor cable with 120° angle between faces, and with 90° angle for a four conductor cable.

Sector-shaped
conductors.

Often employed when more than one core is to be enclosed within a single sheath in order
to achieve a more economic design.  In the case of stranded conductors the shaping is carried out by passing the conductor through special rotating dies or rolls in the stranding machine.

Segmental conductor.    A conductor in which each layer is made up from a suitable number or trapeze shaped wires which fit together to form an annular ring.

Self-Supporting  Cable
-

Made with a steel support strand capable of supporting its own weight across spans.

Semi-C Cable -    See Arrowstraight Cable.
Semi-Conducting    A non-conducting  material made slightly conducting by the addition of a conducting material such as carbon.
Semi-Rigid    A cable containing a flexible inner core and a relatively inflexible sheathing material, such as a metallic tube, but which can be bent for coiling or spooling an placing in a duct or cable run.
Semi-Rigid -    A cable containing a flexible inner core and a relatively inflexible sheathing.
Semiconductor  -    A nonconductive  material made slightly conductive by the addition of a specific sum of


conductive material.
Sensitivity    For a fiber-optic receiver, the minimum optical power required to achieve a specified level of performance, such as a BER.
SER -    Round Service Entrance Cable (type SE, style R).
Series Resistance    Any sum of resistance's installed in sequential order within one circuit.
Serve    Any filament or group of filaments, such as wires or fibres helically wound around a central core.
Serve -    Any filament or group of filaments, such as wires or fibers, helically wound around a central core.
Serving.    A layer or layers of fibrous material impregnated and coated with waterproof bituminous compound applied to the exterior of the cable to give corrosion protection of the sheath and armor.  Additional bitumen is applied over each layer in the machine and the outer surface is coated with whitewash to prevent sticking.
SEU -    Service Entrance Cable (type SE, style U).
Shaped conductor.    A conductor the cross-section of which is other than circular.  Manufactured in stranding machines by passing the strand through special rotating dies or rolls.
Shaped wire.    Can be formed from round wire by drawing through tungsten carbide dies or drawing plates, by power rolling or by free rolling as in a turks head (q.v.).  Either one or a combination of these methods can be used to give one or  more passes to develop a shape. A wide range of products is suitable or can be modified to be suitable for continuous manufacture from a compact traverse wound coil of shaped wire instead of being individually machined from solid metal with higher labor costs and much wastage of time and material.
Power rolling is basically expensive but provides the finishes and accuracy's often demanded and is more versatile than drawing.  Free rolling units for the simpler sections are less expensive, more adaptable and rolls can be changed very quickly, but pulling-in equipment has to be provided.  Advantages claimed for rolling over drawing include:
even increase in tensile strength, whereas tensile strength of drawn material increases more where the deformation has been greatest; higher speeds; fever heat treatments; varying
sizes of flat sided sections by adjusting roll position  dies are made to a specific size; worn rolls produce same wire size after regrinding  dies have to be opened out to larger size; rolls accurately reground on a conventional cylindrical grinder with a template for complex shapes  accuracy of a shaped die depends on dexterity of die maker and becomes more difficult to maintain as complexity of the shape increases; rolled shaped wire can be produced with sharp angular projections and indentations  such sharp corners lead to lubrication breakdown in a die.
Materials in common use in one modern shaped wire mill include mild and high carbon
steels, stainless steel and phosphor bronze.  Square and low aspect ratio flat wires for springs and washers are produced by simple turks head pull rolling.  Higher aspect ratio flat and tapered sections for washers and vehicle upholstery are made by power roll flattening followed by turks head pull rolling.  Flat wire with a convex and a concave edge for flexible conduit is produced with profile ground rolls in a turks head.  A combination
of power roll flattening and turks head pull rolling in intermediate sizes is used for the production of higher aspect ratio flat and tapered wire for washers, circlips, springs and upholstery.  Profile grounds pull rolls are incorporated to manufacture full and half lock coil roping wire.
Shaving aluminum rod.    Where a very high surface quality of aluminum wire is required this can be obtained by shaving the hot rolled rod to remove about 0.075 mm. radial thickness of metal from the surface of the rod by passing it through a specially designed shaving die.
Shaving copper rod.    Where the production of copper wire is required for enameling purposes, it is of paramount importance that the surface of the wire should be completely free of any impurity or imperfection in order that a satisfactory product may be produced.  Shaving of the wire rod has been found to be the most satisfactory way of producing the required


finish.
After a light draw, the hot-rolled rod is shaved by passing through a series of dies, one of which is a shaving die, which removes the requisite amount of material from the circumference of the wire.  For a 12 mm. diameter rod it has been stated that the diameter should be reduced by 0.6 mm.  The input size should be as large as possible, as the larger the diameter of wire which is shaved, the smaller the proportion of scrap produced.  It has been found in practice that the minimum entry rod for shaving is 9.5 mm. diameter soft copper and that the optimum size is 16 mm. diameter.  The sequence of operations on 9.5 mm. dia. rod is:  rounding-up die (7.6 mm.); marking of the rod with a shallow spiral groove to facilitate break-up of swarf during shaving; shaving die (7mm); and final drawing die (6.1 mm).  Cold drawing should, of course, follow the shaving operation, and this process can be carried out continuously in series with the wire-drawing machines.
Other approaches have been made to the problem including machining (scalping) of the wire bar followed by no further treatment of the rod or wire to improve the surface,
various scouring methods designed to remove the surface layers by abrasion, and very careful control during rolling and drawing in order to produce a product with a surface of good quality.  Shaving is, however, considered to be the only really satisfactory method.
Sheath    The material, usually an extruded plastic or elastomer, applied outermost to a wire or
cable.  Very often referred to as a jacket.
Sheath -    The material, usually an extruded plastic or elastomer, applied on the outside of a wire or cable.  This is very often referred to as a jacket.
Sheathing.    Provision of an outer protective covering for cables.  It is usually extruded and is of either tough rubber, thermoplastic, lead or aluminum.  A further protection against corrosion and mechanical damage may also be given to the sheath itself, particularly if it is of metal. Protection against corrosion usually takes the form of bitumen, bituminized paper, hessian, etc., or P.V.C. wire or metal tape armoring (q.v.) is often applied over hessian or jute bedding to guard against mechanical damage.
Aluminum cable sheathing.  There are three basic methods of providing an aluminum sheathing on cables:
1.    The cable core may be inserted into an oversize tube of aluminum which is then rolled or swaged so that it becomes a close fit on the cable core.  The cost of forming this tube is high compared with other methods and there is a limitation on the length of the sheath depending on the billet used for the extrusion process.  Where more than one billet has been used the stop marks have not proved to be of the same high quality as the tube and therefore when a billet is changed a fresh run of tube is started.
2.    A tube is formed by folding aluminum strip around the cable core and jointing the edges either by pressure welding, by argon-arc welding or by induction  heating.
3.    An aluminum sheath may be extruded directly over the cable core, taking care to keep heat away from the core while the extrusion operation is performed.  One method is to wind an aluminum foil over the cores before the sheath is extruded.  By this process long lengths of sheath may be extruded at one time obviating stop marks.
Aluminum sheathing is light, has good mechanical strength and resistance to vibration, high conductivity and good screening properties to A.C. hence its use in British Railways 25 kV electrification.   It often obviates armoring, usually required with lead sheaths.
Corrosion can be overcome by applying a thin P.V.C. sheath over the aluminum where
the cable would generally be laid in the ground or in ducts without further protection offered by usual servings.  The grade of material often used for cable sheathing in extruded form is 99.5 percent purity aluminum to B.S. 1471 with limited impurities, particularly regarding copper, the presence of which tends to initiate corrosion.  Cables to B.S. 6480, and to B.S. 6007 and 6500 utilize aluminum sheath, but apart from A.C.
applications, where the screening properties are advantageous, the economies of aluminum compared with lead determine its use in many cases.


Lead-covered cable.  A cable provided with a lead sheath for the purpose of excluding moisture from the conductors and insulation; also used as earth return.  The sheath consists either of commercially pure lead to which a small percentage of rarer metals has been added for hardening purposes.  The extrusion of lead and its alloys in the screw type of continuous machine, as used in cable making, from time to time runs into difficulties, particularly with the harder alloys.  The factors which affect the extrusion include the surface friction characteristics between lead and steel, the hot shear strength of the lead alloy, and the adhesion between the lead and the steel.
Different screw speeds are necessary for different alloys depending on the hardness of the alloy.  Alloys such as 0.85 percent antimony, and 0.5 percent antimony 0.25 percent cadmium, can only be extruded satisfactorily at relatively low rates.  Careful control of certain impurities, notably copper and silver, is essential, since their presence can cause segregation resulting in defects such as blisters, ridges or wrinkles on the inside or outside of the sheath.
The lead sheath may be reinforced by metal tapes against internal pressure in pressurized cables.
Testing lead sheaths.  There must be an adequate and uniform thickness of lead.  A quality control device, to be practical, should be able to measure sheath thickness in the middle of the run, not just at the ends.  An ultrasonic gauge does this, and can give eccentricity tolerances of  7 percent of the average wall thickness, or less than half those required for minimum quality by industry or customer acceptance specifications.   See entry for ultrasonic gauge.

Shield    In cables, that metallic layer applied over the dielectric or group of dielectrics, composed of woven braided, or served wires, foil wrap or tubular metallic construction to prevent electrostatic or electromagnetic  interference between the enclosed wires and external fields.
Shield -    Power Cable, see strand shield, insulation shield.  Communications  cable-a covering consisting of any of the following:  foil wrap, continuous tube, metal wire braid, applied over a conductor or cable used to prevent electrostatic or electromagnetic  interference between the shielded conductor(s) and it's surrounding field.
Shielded Cable -    Usually concerning a high voltage power cable 5000V and above enclosed in a nonmagnetic conducting envelope, so constructed that substantially every point on the insulation is at ground potential or some pre-determined  potential with respect to ground. Can apply to multiple conductor cable in which each single conductor is shielded or to a multiple conductor cable where the overall assembly is shielded.
Short Circuit -    Loads which occur during fault conditions and are characterized by very heavy current flow.
Shot noise    Noise caused by random current fluctuations arising from the discrete nature of electrons.
Shunt    A device used to divert part of an electric current.
Signal    An electric current used to convey information either digital, analog, audio, or video.
Signal-to-noise  ratio    The ratio of signal power to noise power.
Silicon bronze wire.    Consists of about 3 percent silicon, 1 percent manganese and the balance copper.  It is strong and tough with excellent corrosion resistance.  The tensile strength of this alloy is greater than that of brass and comparable to that of many ferrous materials, varying
between about 40 kg./mm②   in the annealed condition to upward of 85 kg./mm②   when
hard drawn.  Applications include nails, rivets and wood screws for boat-building and fitting, cold heading, thread rolling, and springs.  Also woven wire filters for such purposes as brewing, waterworks and sewage disposal plant.

Silicon manganese nickel wire.

A nickel base alloy wire containing from about .5 to 3 percent manganese and from 1 to 4 percent nickel, has a very high resistance to corrosion and high-temperature  effects.

Silicon-manganese alloy.    Steel alloys with an approximate composition of 2 percent silicon and 1 percent manganese are often used for springs subjected to sever fatigue conditions, while 1.8 to


2.5 percent silicon, 0.70 to 0.90 percent manganese and 0.50 to 0.70 percent carbon composition is used for instrument springs.
Silicon.    A powerful de-oxidizing agent, its inclusion improves the physical properties of steel.
Combined with manganese, it is used in materials for springs of various types, and give best service in this capacity when combined with a carbon content of from 0.45 to 0.70 percent.  A silicon content generally limited to 4 percent is used for electric resistance wires as it increases electrical resistance.
Silicone rubber.    Possesses great chemical stability, and what is for a rubber-like material an extraordinary degree of heat resistance, in that it can be used for cable insulations at temperatures up to about 150 deg. C. for long periods without any apparent changes.  It usually needs some form of external protection.  Cables of this type are costly and are used in specialized applications such as wiring of flues and brick kiln where high temperatures are encountered and also in aircraft and naval ships.
Silver steel wire.    A general purpose wire manufactured from high carbon steel, .95 to 1.25 percent carbon, used for drills, spindles, pinions, etc. A widely used specification is that laid down in B.S.
1407.
Simplex cable    A term sometimes used for a single-fiber cable.
Simplex transmission    Transmission in one direction only.
Single-mode fiber    An optical fiber that supports only one mode of light propagation above the cutoff wavelength.
Sinter    To thermally cure or treat a material.
SIS -    Rubber insulated Switch Board Wire, 90øC.
SJ -    Portable cord junior hard service.  Rubber insulated 300V.
Skin Effect -    In an alternating current system, a phenomenon that occurs at increased frequencies causing an increase in resistance of the conductor leaving the outer skin to carry most of the current.  The phenomenon increases in intensity the higher the frequency.
Skin effect.    The tendency of alternating current flow to concentrate at the surface of a conductor.
Skived Tape    Tape shaved in a thin layer from a cylindrical block of material.
Slip.       (1) On a wire-drawing machine the difference between the circumferential speed of the drawing blocks and the surface speed of the wire.  In slip type machines, the capstans are driven faster than the wire which skids over them, the drawing liquor preventing undue wear.  To avoid slip, special costmeet variations of elongation in the wire so that the capstans run at the same speed as the wire being drawn.
(2) The mechanism of deformation wherein one part of a crystal glides over another part along certain planes known as slip planes.
Slip bands are a microstructural feature showing as a series of parallel lines across individual crystals when a polished surface is deformed cold.
Smooth-conductor cable.    A cable in which a smooth metallic layer in intimate contact with the conductor is interposed between the conductor and the dielectric; the object is to provide the conductor with a smooth surface instead of the corrugated surface existing in the case of a stranded conductor.


Snake type strander.    An alternative name for a tubular strander (q.v.), in which the stranding bobbins are mounted in floating frames along the center line of a large rotating tube.
SNR    Signal-to-noise  ratio.
Soaking.    Holding steel at a certain temperature for a period sufficient for uniform heat penetration, and to permit essential changes to take place.
Soft drawn wire.    Drawn with a reduction of area from the rod or annealed base of about 10 percent.
Solid cables.    Refers to all designs of medium and high voltage paper-insulated  power cables except pressurized types.
Solid Conductor -    A solid conductor is a conductor is a conductor consisting of a single wire.
Solidal cable.    A  P.V.C.-insulated  power cable with solid aluminum phase conductors and concentricaly


applied neutral conductor comprising aluminum strips.  A trade name.
Solution    An optical pulse that does not disperse over distance.
Solution heat treatment.    Heating of an alloy to a pre-determined  temperature, holding it at that temperature to enable a maximum amount of the secondary phase to dissolve in the primary phase, followed by cooling to room temperature.  Heating temperature is governed by the melting point of the constituents and the prevention of excessive grain growth.
Sonet    Synchronous optical network, an interational standard for fiber-optic digital telephony.
Source    The light emitter, either an LED or laser diode, in a fiber-optic link.
Spacer Cable -    A distribution cable designed to be used in conjunction with insulating spacers which maintain conductor spacing in overhead line installations.  This cable is considered uninsulated and installed likewise, but the covering on the conductors does allow for conductor close proximity and reduce faults due to the touching of tree limbs.

Spark Test    A test designed to locate pin-holes in an insulated wire by application of an electrical potential across the material for a very short period of time while the wire is drawn through an electrode field.
Spark Test -    Test given to wire or cable to determine if there are defects in the insulation.
Spark testing.       1.    A means of testing cable by passing it through a metallic electrode which makes contact with the surface.  The electrode is maintained at a high voltage with respect to the cable conductor, which is earthed, and when a fault in the cable insulant enters the electrode, a spark passes.
2.    A simple method of identifying the approximate carbon content of a steel by  holding it against a grinding wheel when the type of spark indicates the approximate carbon content.  With experience the presence of the common alloying metals can also be identified.  Also, if the steel composition is known and the spark indicates a lower carbon, this shows that decarburization  has taken place.
Specific Gravity    The ratio of the weight of any volume of substance to weight of an equal volume of some
substance taken as a standard, usually water for liquids and hydrogen for gases.
Spectral width                    A measure of the extent of a spectrum.,  for a source, the width of wavelengths contained in the output at one half of the wavelength of peak power.  Typical spectral widths are 20 to 60 nm for an LED and 2 to 5 nm for a laser diode.

Spinner.    In a straightening and cutting machine, a rotating member, containing the dies which straighten the wire.  The wire does not rotate.
Spiral Wrap    A term given to describe the helical wrap of a tape of thread over a core.
Spiral Wrap -    A term given to describe the helical wrap of a tape or thread over a core.
Splice    An interconnection  method for joining the ends of two optical fibers in a permanent or semipermanent fashion.
Splicing.    The joining of two ropes by cutting out alternate strands from the end of each rope, the length of cut being determined by the diameter, the remaining strands being interlaced in place of the strands cut out of the outer rope.
Spooling.    Winding wire on to a spool in an exact pattern and at a carefully controlled tension.
Precise operation of the spreader, which traverses the wire across the spool, is essential, particularly in regard to the dwell as it reaches each flange.  The speed of the drive also has to reduce steadily to take account of the coil diameter as the spool is filled.
To enable continuous production to be maintained at high speeds, automatic spool changeover is frequently provided.  Two spools are mounted side by side and while one spool is receiving the wire, an empty spool is placed on the other spindle and driven so
that the spools are running together at the same linear speed.  When the first spool is full, a
guide arm transfers the wire to the empty spool, and when sufficient turns have been put on to the empty spool, a knife automatically severs the wire between the full and empty spools.  Since the linear speed of the empty spool is not exactly that of the full one, an accumulator (q.v.) must be included before the spooler to take up the excess wire until the


spooling speeds are matched.
In nonferrous wire-drawing  there is a tendency to change from coils to reels of very large dimensions such as 1.5 tons.  The reason is the advantage gained from heavier pieces.  The reel offers protection in handling and transport for copper wire, which in the soft condition is very soft.  With this shift to spooling, precision of the spreader is very important, but this need is adequately met by the machine manufacturers.   The spooling tension must be carefully controlled if annealing is to be carried out on the spools, for if
the wire is too tight, welding will occur between the coils.  Many machines producing rope wire are provided with spooling devices, the spools being the same as those used in the stranding machines.  This eliminates a separate winding operation.
When nonferrous wire is annealed on spools, discoloration of the outer wires on the
spool can be lessened by lapping the loaded spools with copper strip or fine copper wire. The discoloration can be eliminated by using spools with the flange in two parts  an
inner part with a number of radial arms integral with the barrel; and a detachable outer part
consisting of a disc with projections on its inner face to fit between the arms to provide a smooth inside wall.  During winding both parts of each flange are used.  During storage, shipment or annealing, only the inner parts of the flanges are in use.  Lower grade steel can be used for spools of this type, and furthermore one pair of outer flange parts can be used with a large number of the inner spools.
During storage and transport, spools can now be protected by an expanding corrugated paper sleeve.  The elasticity of the sleeves allow them to be passed over the flanges and they then contract to lie between the flanges and grip the wire.
SPT -    All parallel construction, thermoplastic jacket, two conductor portable service cord, for lamps and small appliances, clocks, radios.
Square Mil -    The area of a square, one mil by one mil.
ST -    Thermoplastic jacketed service cord, portable use.

Stabilized wire and strand.

Prestressed concrete wire and strand which has undergone special treatment to further improve quality beyond that achieved by normal stress-relieving.   Wire is plastically stretched about 1 percent while it is at a temperature of 350 to 400 deg. C.  It is thought that this has the effect of creating more dislocations and also directing precipitates to where they are most needed., i.e. on planes where slip is actually taking place.  The very short time involved also ensures that precipitate growth is restricted and is therefore more effective.  The overall effect is to raise the limit of proportionality to a value about 80 percent of the u.t.s., the 0.1 percent proof stress to 90 percent and to reduce relaxation losses to about one fifth those of stress relieved wires.
As applied to strand, stabilizing gives properties more or less identical to those of stabilized single wires.  After stabilizing, strand has the added advantage of being perfectly straight without any pre- or post-forming operation.  In addition the individual wires are so closely compacted that it is possible not only to part the strand with a slitting
wheel without any tendency for the wires to move, but also to unthread and refit the helical wire without difficulty, thus facilitating handling on site.
The process of stretching 1 percent also ensures that all strand is automatically tested;
thus any faults in the wire are found during production rather than during prestressing.

Stabilizing.                               A term applied to a GKN process for increasing the elastic limit of hard drawn carbon steel wire used for prestressing purposes.  The effect is to increase resistance to stress relaxation.  The process involves straining at elevated (400 deg. C.) temperatures.
Stainless steel.    High chromium steel, often including nickel, which is resistant to corrosive and oxidizing influences.  The best known form of stainless steel is 18-8, an austenitic steel containing about 18 percent chromium, 8 percent nickel, the carbon content being kept low.  A suitable solution for cleaning 18-8 stainless and similar qualities is 35 percent hydrochloric acid, 5 percent nitric acid, 5 percent restrainer and 55 percent water.
Star coupler    A fiber-optic coupler in which power at any input port is distributed to all output ports.
Star network    A network in which all terminals are connected through a single point, such as a star


coupler.
Star quad.    Telephone cables consisting of four individual insulated conductors twisted round a paper or other core to form one unit, with the conductors at the four corners of a square, diametrically opposite wires being used to provide the circuits.  Have largely displaced multiple twin types as the star quad has a lower pair capacitance and can therefore provide up to 50 percent more circuits of the same capacitance in a given size of cable.
Stationary blocks.    Blocks on which the wire is wound by a rotating arm thus producing a stationary coil.   A difficulty is that a twist is put into the wire as each turn is wound on the block.  Killing rolls are used to assist in "casting" the wire.  Owing to inherent twist in the wire, application is limited to milder qualities and sizes.
The maximum speed of a coiling unit of this type fitted with a 700 mm./dia. block is approximately 12.5 m./sec. as at about this speed the angle of wire pay-off is horizontal and the wire is deflected by the rotor arm.  Within these limitation of wire quality and
speed, these units have considerable value in permitting continuous running of the drawing machine to produce coils of any weight and size.  Continuous running is achieved by
means of a conveyor which received the wire beneath the rotor arm and transfers it to the tubular former below; when this former is full the wire is cut and the wire builds up on the conveyor while the conveyor is swung over another empty former.  A similar effect is achieved with vertical units by allowing the wire to build up on the "neck" of the guides which transfer the coils of wire to the horizontal plane before they drop onto the former.
Steady state    Equilibrium mode distribution.
Steel cored aluminum.    An alternative name for aluminum conductor, steel reinforced (q.v.)
Steel wire gauge.    The commonly used name in the United States for Washburn & Moen Gauge.  It is used by practically all steel wire manufacturers in the United States, though sometimes under other names.  For copper and other nonferrous wires, American Wire Gauge (Brown and Sharpe Gauge) is used.  Anew series based on the preferred number series is also being introduced in the U.S.A., intended to replace all gauges in common use.
Step-index fiber    An optical fiber, either multimode or single mode, in which the core refractive index is uniform throughout so that a sharp step in refractive index occurs at the core-to-cladding interface.  It usually refers to a multimode fiber.
Sticking of copper wire.    Occurs during annealing of copper wire on spools when adjacent turns of wire become welded together.  It can be minimized by avoiding excessively tight windings or high annealing temperatures.  Annealing of deoxidized or oxygen-free coppers in a reducing atmosphere may also cause stickiness by reducing superficial oxide films that would otherwise tend to inhibit the welding process.  Annealing in a vacuum is being widely adopted, partly to eliminate stickiness.  The slower annealing cycle time can be shortened by introducing an inert gas during the cooling-down period following the annealing operation.  Experiments have shown that an invisible film of lubricant left on the wire after drawing can have a marked beneficial effect in preventing sticking.  Sticking is sometimes also referred to as welding together.

Straightening  and cutting machines.

In the usual type of machine, wire from the coil is drawn into the machines by a pair of push feed rolls, passed through a rotating spinner containing dies to straighten the wire and then pulled by a further pair of feed rolls to a cutting mechanism which cuts off any predetermined  length.

Strain aging.    The slow rise in hardness and tensile strength which occurs in some metals at room temperature, after cold working.
Strain.    Deformation produced by a stress and expressed as the change per unit of original dimension or in the case of shear as angular displacement.
Strand    A single uninsulated wire.
Strand -    One of the wires, or one of the groups of wires of a stranded conductor.  Also a term applied to steel strand.
Strand Lay    The distance of advance of one strand of a spirally stranded conductor, in one turn, measured axially.


Strand Lay -    The distance of advance of one strand of a spirally stranded conductor, in one turn, measured axially.
Strand Shield -    A layer of semiconducting  material or tape applied directly over the stranded conductor of cables rated 2000 volts and higher.  This reduces the possibility of high stress points occurring between the conductor and insulation.
Stranded bunch.    A number of bunches twisted together so that each bunch (q.v.), with the exception of the center one, has a helical form of predetermined lay ratio.  When the number of bunches exceeds four they are arranged in concentric layers, alternate layers usually being stranded in opposite directions.
Stranded Conductor -    A stranded conductor is a conductor composed of a group of wires, or of any combination of groups of wires.
Stranded conductor.    A conductor made up of a number of wires twisted together, usually built up on a single central conductor, with 6 wires in a first layer, 12 in a second, 18 in a third, and so on. Most conductors therefore have 7, 19, 37, 61 or 91 wires, frequently designated 7/0.74 mm. Or 37/2.1 mm., the first number showing the number of wires and the second the diameter of the individual wires in inches.  When there is more than one layer in a stranded conductor, the direction of lay is reversed in adjacent layers.  Oval or sector shaped conductors are often used where more than one core is to be enclosed in a single sheath.

Strander machine/Planetary stranding machine.

A wire rope stranding machine of the planetary type is one in which the spools of wire are supported in cradles suspended in a rotating carriage; the cradles supporting the spools operate with planetary motion derived from sun and planet gearing located at one end of the rotating carriage.  The wires are led from the spools through the front trunnion of the supporting cradles to the lay plate, forming die and then to the capstan haul-off and the take-up drum.  The rotating carriages for planetary stranding machines are frequently arranged to accommodate spools of wire in multiples of six, i.e. 6, 12, 18, etc., but other arrangements occur. A disadvantage of these machines is the restriction on their speed and excessive down time as compared with tubular type machines.


Stranding dies.    A pair of steel blocks, which when put together in a die holder, form a circular or sector shaped hole through which the stranded wires pass to form the finished strand.
Stranding.    Laying together of a number (generally 3,7,19,37,61,91,127 or 168) of hard or soft wires in such a way that each wire holds its place in the strand.  For details of equipment used in stranding, see entries for tubular strander, planetary strander, and reels.  A number of stranding machines may be coupled together; for example in a triple tandem strander for
37-wire strand, the first machine spins six wires round a core wire, this strand being led through the center of a 12-bobbin machine making 19 wires and on being led forward again through an 18-bobbin machine, a 37-wire strand is formed.

Strength member    That part of a fiber-optic cable composed of Kevlar aramid yarn, steel strands, or fiberglass filaments that increase the tensile strength of the cable.
Stringing-up.    Threading a wire, after pointing the end, through successive dies and round successive capstans until a wire drawing machine is ready to commence running.
Strip.    Orders should specify width, thickness, whether in straight lengths or coils; radius of corners, if rounded.  If coiled, weight of coils.  Temper (annealed, 1/4, 1/2, or 3/4 hard, hard, spring hard or by Brinell or diamond pyramid number).  Strip is usually considered to refer to material between about 1.5 mm. And 9.5 mm. Thick and a width not over 460 mm.; thinner material is known as foil and thicker material as plate. Strip is often in fact flattened wire (q.v.).  Narrow strip in both ferrous and nonferrous metals is produced for many  purposes by rolling wire as described under the entry for flattened wire, or in some
cases by a combination of drawing and rolling as described under the entry for transformer strip.
Submarine power cable.    Used to transfer surplus power between areas where peak demand occurs at different times























Submarine telephone cable.










Subscribers' telephone cables.

or to supply islands from the mainland.  Because of difficulties in repairing and strains which may occur in laying, particular care has to be taken to avoid damage or corrosion  a much greater problem with heavy power cables than with submarine telephone cables. Details of some of the constructions employed can be seen from two examples.
The cable used for the cross-Channel power link is of the impregnated paper insulated
solid type.  It is of 370 mm2 cross section and consists of stranded copper wire lapped with an electrostatic screen.  The solid type impregnated paper insulation, also lapped externally with an electro-static screen, is sheathed with lead alloy "E" which is protected against corrosion by vulcanized rubber tapes.  Armoring is provided by a single layer of
5.9 mm. Galvanized steel wires with appropriate beddings and servings.  Anti-twist tapes
are applied over the lead sheath and under the anti-corrosion protection to ensure that the cable is not damaged during recovery.
The three 250 kV D.C. power cables across the Cook Strait, New Zealand, are of single core gas filled type; each was made in a continuous length and weights 1,500 tons.  A hollow steel strip spiral duct has copper wires stranded over it in two layers to form the conductor, which is screened by metallized paper, lapped with impregnated paper tape and screened with copper tape.  This is contained within a lead alloy sheath reinforced with four layers of steel tape, this reinforcement being protected against corrosion by a vulcanized tough rubber sheath and against marine borers by bras tapes.  The armoring consists of 5.9 mm. Heavily galvanized 60/70 ton steel wires on a bedding of jute strings. The latest type of deep sea coaxial cable has no external steel wire armor.  A single cable
to carry speech in both directions will provide 60 telephone circuits.  The strength member is a steel strand placed at the center which is ineffective so far as carrier-frequency transmission is concerned.  Steel of a much higher tensile strength  190 kg./mm.2  can be used in strand form, and the strand can be designed to be balanced so that there is no tendency to twist under tension.  Deterioration of the strength of the cable through corrosion of the steel strand is also completely eliminated.  The central steel strand is enclosed in a copper tube to provide the central conductor, and insulated with
polyethylene to a diameter of approximately 25 mm.  Aluminum tapes (outer conductor)
together with a polythene binder tape and one aluminum screening tape with a polethylene interleaving tape are applied, and the whole given a lapping of anti-corrosion tape and an outer covering of polyethylene to an overall diameter of about 32 mm.
Many of these consist of bare overhead copper conductors, but in towns insulated under ground cables are usual.  In the for example, the cables used between the exchange and the distribution cabinet are unit twin types with between 100 and 4,800 pairs in wire of 0.32 to
0.9 mm. Dia.  Paper and polyethylene insulation is used and the cable is polyethylene/aluminum laminate sheathed; it is pressurized to provide protection against ingress of water.  From the cabinet to the subscriber, cables containing 100 pairs and less of 0.4 to 0.9 mm. Dia. Copper wire are used also aluminum alloy wires of 0.5 mm. Dia. These cables are insulated with cellular polyethylene and polyethylene sheathed. Following difficulties with water ingress through small pin-hole faults in the insulation, these cables are now fully filled with petroleum jelly (q.v.) during manufacture, it is important to choose cellular polyethylene and a grade of petroleum jelly which are compatible.  In the U.K. each layer of the cable is separated from the others by a narrow polyethylene binding tape, so that it is most convenient to apply the filling layer by layer as the cable is built up.

Sun and  planet strander.    A strander in which the spools of wires are supported in cradles suspended by a rotating carriage, the cradles moving with a planetary motion.  See entry for Stranding machine/planetary  stranding .
Superconductive  wire.    Wire that is superconductive,  i.e., wire that has no electrical resistance at temperatures near 0 deg. absolute.
Surface Resistivity    The surface resistivity of a material is the ratio of the potential gradient parallel to the current along its surface to the current per unit width of the surface, usually expressed in


ohms.
Note:  Surface resistivity of a material is numerically equal to the surface resistance between two electrodes forming opposite sides of a square, the square size being immaterial.
Surface Resistivity -    The resistance of a material between two opposite sides of a squared unit (of measurement) of its surface.
Suspension cables.    For suspension bridges of great span a large number of parallel galvanized high tensile steel wires are used, the wires running backwards and forward the length of the bridge in one long length, secured in strand shoes at each end.  Groups of wires are banded at intervals for form strands and the strands are then squeezed tightly together with hydraulic jacks to form a compact circular section.  Cable bands of cast steel are then bolted around the cable at intervals and over these are placed long wire rope suspenders which hang down and carry the deck of the bridge.  The cables are painted and wrapped around with binding wire between the bands.
The suspension cables of the Forth Road Bridge are each made of 11,618 parallel wires, divided into 37 groups or strands, and are about 570 mm. Dia.  The lighter streamlined deck structure of later bridges needs lighter suspension cables; in the Severn Bridge for example 8,000 parallel wires are gathered into 20 strands to form a cable of about 500 mm. Dia.
With a later method, used in the Rhode Island bridge, smaller parallel-wire strands are precision-manufactured, measured and banded in the shop, placed on reels and then socketed.  Each strand is erected on the bridge towers by simply towing the socketed leading end across; the strand is then adjusted to its correct sag in the cable.  This avoids the lengthy process of spinning the bridge cables wire by wire.
Swaging, rotary.    A means of reducing the ends of rods, tubes, and wire by rotating hammers and dies.  The shape of the dies decides the reductions to be produced.
Swift.    The simplest type consists of a rotating holder on a vertical pillar, the wire being uncoiled by the pull exerted by the machine or equipment which it is supplying.  A refinement of this type is a tipper swift which has a spring loaded base so that it may be tilted to facilitate loading and unloading and can then be positively locked when returned to its normal position.
Many wire manufacturers have developed swifts of their own design to operate with high speed equipment and to facilitate changing a new coil after welding on.  With a flipper swift, each warp of wire is pulled off a stationary coil of wire on a horizontal or inclined pole or framework.  The boom of a boom truck can be made detachable so that the complete boom load of wire can deposited on a special cradle to form such a flipper swift.
A turntable of flipper swift with a number of arms is sometimes used for supplying high speed machines, the end of a coil on one arm being welded to the front of the coil on the next.  By turning the apparatus on its turntable base, a continuous supply of rod or wire is thus assured.  Double headed swifts are employed for supplying furnaces, galvanizing plant, etc.  With these swifts, the coil in use is on the base of the swift and its end is joined to another coil supported by arms halfway up the swift.  When the lower coil is nearly exhausted, by turning a simple release on top of the swift, the upper coil is allowed to fall to the base.
Power-operated  swifts are employed for feeding one ton coils without any drag, being adjusted to the speed of the machines they are serving.
Switchboard cable.    Similar construction to subscribers' telephone cable (q.v.), containing paired, tripled or quadded insulated conductors but used for internal wiring of telephone exchange apparatus.
Switchboard Wire    Chemically cross-linked polyethylene or asbestos insulated wire resistant to heat, flame
and corrosive vapor.
T -    Thermoplastic.


TA -    Thermoplastic and asbestos insulated switch board wire, 90øC.
Take-Up -    The process of accumulating wire or cable onto a reel, bobbin, or some other type of package.  Also refers to the device utilized for pulling wire or cable through a piece of equipment or machine.


Tandem drawing machine.

Wiredrawing machines arranged with two or more dies in succession.  See further details under the entry for wiredrawing machines.

Tandem mill.    Rolling mills arranged in a direct line so that the material passes from one set of mills to the next.
Tank Test    A term used to describe a voltage dielectric test where the specimen to be tested is submerged in a liquid (usually water) and a voltage potential applied between the conductor and the liquid as ground.
Tap loss    In a fiber-optic coupler, the ratio of power at the tap port to the power at the input port.
Tap port    In a coupler in which the splitting ratio between output ports is not equal, the output port containing the lesser power.
Tape Wrap    A term denoting a spirally or longitudinally applied tape material wrapped around the wire, either insulated or uninsulated, used as an insulation or mechanical barrier.
Tape Wrap -    A term denoting a spirally or longitudinally applied tape material wrapped around the wire, either insulated or uninsulated, and used as an insulation or mechanical barrier.
Taper drafting.    Employing a reducing area reduction throughout a wire-drawing machine, thereby evening out the motor loads on a machine employing a motor of the same power to each block, so enabling a greater output to be achieved.
Taping machine.    These are of three main types.
The tangential type taping machine usually consists of a series of eight pads arranged in four pairs, each pair being mounted on a suitable stem projecting from a rotating head on a hollow mandrel through which passes the cable to be taped.  All the taping heads can run
in the same direction or they can be made to run with alternate heads reversed.  The lay is determined by the relative speed of the cable and the head.
The vertical cage type taper has the capstans at the top of the frame and the take-up drums on the opposite side of the machine to the taping heads.  There are usually four or more vertical cages side by side, each cage having a number of taping heads all running in the same direction at constant speed.
the horizontal cage type taper has a number of radial arms fastened to a common
spindle and enclosed in a cage.  Up to about 200 tapes can be applied in one operation by operating a number of these cages in series.

Taping machines.    Machines for covering electric cable with tape for insulating purposes.  One machine for winding tape on to large wire conductors rides on the wire itself after this has been threaded through the machine before being joined to the coil former.
Tarnish    A term used to describe a discolored or stained conductor or shield wire caused by
exposure to the atmosphere.
Tarnish -    A term used to describe the discoloration of a material caused by exposure to a corrosive environment.
TAS -    Shielded thermoplastic appliance wire.
TBS -    Thermoplastic and fibrous outer braid, 90øC switch board wire.
TBWP -    Triple braided weatherproof cable.
TDM    Time-division multiplexing.
Tear Test    A test to determine the tear strength of an insulating material.
Tee coupler    A three-port optical coupler.
Teflon.    Trademark of the DuPont de Nemours Co. For Polytetrafluoroethylene.
Telephone cable.    In most cases is formed by assembling a number of small cables consisting of  two, three, or four insulated copper or aluminum wires twisted together, but tubes and strip are used in coaxial cables.  See entries for unit cable, star quad, subscriber telephone cable, carrier


frequency trunk telephone cables, coaxial cable and submarine telephone cable.  The annealed copper wires used in telephone cables other than coaxial types are usually of the following standard diameters: 0.32 mm.; 0.4 mm.; 0.5 mm.; 0.63 mm.; 0.9 mm.; 1.0 mm.;
1.2 mm.; and 1.27 mm.  Aluminum wires have to be of larger diameter for equal
performance.  Paper has been widely used as the insulating material for telephone cables, loosely wrapped round the copper conductor so that advantage is taken of the properties of air as an insulant, but polyethylene is increasingly used.  Polyethylene, either solid or with some form of air spacing, is now widely used in telephone cables, polyethylene insulated telephone distribution cables being specified in B.S. 3573.  Testing of the finished cables
is on a sampling basis using Quality Assurance techniques, although the electrical characteristics of long distance audio cable are tested with automatic testing sets which carry out unbalance and mutual capacitance tests, and measure the insulation resistance of each wire.
The worst enemy of the telephone network is water seeping into cables through holes or cracks in the sheaths.  This will be a greater problem for cables with aluminum conductors, since aluminum is much more vulnerable to corrosion than copper.  The Post Office in the U.K. has filled most of its cables with dry compressed air, so considerably reducing the effect of cable sheath faults.  Internal air pressure of 0.070 kg./cm2 above normal atmospheric pressure is sufficient to prevent water entering a small hole or crack even
when the cable is under 600 mm. of water. For subscribers' telephone cable (q.v.), water seepage is prevented by filling the cable with a water impermeable medium based on a pharmaceutical  grade of petroleum jelly.


Temperature Coefficient of Resistivity

The amount of resistance change of a material per degree of temperature rise.

Temperature Stress    The maximum stress which can be applied to a material at a given temperature without physical deformation.
Tempering.    Heating hardened, normalized, or mechanically worked steel to some temperature below the transformation range, and holding for a suitable time at that temperature, followed by cooling at a suitable rate.  This process is usually applied for the purpose of producing a desired combination of mechanical properties, as for instance in valve spring wire.

Tensile Set -    The condition when a plastic material shows permanent deformation caused by a stress, after the stress is removed.
Tensile Strength    A term denoting the greatest longitudinal tensile stress a substance can bear without tearing apart or rupturing.
Tensile Strength -    A term denoting the greatest longitudinal tensile stress a substance can bear without tearing apart or rupturing.
Tensile strength.                     The maximum load reached in a tensile test divided by the original cross-sectional  area of the gauge length portion of the test piece.  Also termed maximum stress or ultimate tensile strength.
To find the tensile strength of round wire in kg./mm2 divide load in pounds by the square of the diameter, and by 10.  The result is the tensile strength in tons per sq. in.
Tensile Stress    Force per unit cross-sectional  area applied to elongate a material.
Tensile test.    Performed by griping both ends of the wire or material to be tested, applying a pulling force to one end, and to the other a tensional load of sufficient capacity just to balance the applied load.  The tensional strength, expressed in Newtons, is the maximum load which the wire will satisfactorily withstand prior to fracture.
Tension Set    The condition when a plastic material show permanent deformation caused by a stress, after the stress is removed.
Test Reports -    The permanent records made by a wire manufacturer of the tests performed on a batch of wire to a specification.


TF -    Thermoplastic covered fixture wire, with solid or 7 strand conductor.
TFE -    Teflon insulated cable, 250øC dry location, for apparatus leads.
TFF -    Thermoplastic covered flexible fixture wire, with stranded conductor.
Thermal Aging    Exposure to a given thermal condition or a programmed series of conditions for prescribed periods or time.
Thermal Aging -    Exposure to a given thermal condition or a programmed series of conditions for predescribed periods of time.
Thermal Alloying    The act of uniting two different metals to make one common metal by the use of heat.
Thermal Expansion    The expansion of a material when subjected to heat.
Thermal Expansion -    The expansion of a material when subjected to heat.
Thermal noise    Noise resulting from thermally induced random fluctuation in current in the receiver's load resistance.
Thermal Rating    The maximum and/or minimum temperature at which a material will perform its function without undue degradation.
Thermal Rating -    The maximum and/or minimum temperature at which a material will perform its function without undue degradation.
Thermal Resistance    That change in the electrical resistance of a material when subjected to heat.  Resistance to heat flow from conductors to outer surface of insulation or sheath in a wire or cable.

Thermal Resistance of a Cable -

The resistance offered by the insulation to the flow of heat from the conductor(s) to the sheath.

Thermal Resistivity    Thermal resistance of a unit cube of material.
Thermal Shock -    The resulting characteristics when a material is subjected to rapid and wide range changes in temperature in an effort to discover its ability to withstand heat and cold.
Thermocouple    A device consisting of two metals usually in wire form joined in two places.  If a temperature difference exists between the junctions, a voltage is generated which can be calibrated to indicate temperature.

Thermocouple Lead
Wire

Similar to thermocouple wire except the degree of accuracy in temperature measurements is not as high and it is used to transmit thermocouple information to remote indicators.

Thermocouple Wire    A two conductor cable, each conductor employing a dissimilar metal, made up specifically for temperature measurements.
Thermocouple Wire -    A two conductor cable with each conductor employing a disimilar metal, made up specifically for temperature measurements.
Thermoplastic    Insulation that will resoften and distort from its formed shape by heating above a critical temperature peculiar to the material.
Thermoplastic  -    Insulation that will soften and distort from its formed shape by heating above a critical temperature peculiar to the material.

Thermoplastic
Elastomer

Used for insulation and jacketing compound for portable cords with the following U.L. designations. SE, SEO, SRDE, SPE, SJE, SJEO.

Thermoplastics.    Materials which are deformable at elevated temperatures and harden again on cooling, retaining the shape imparted to them when hot.
Thermosetting    Term describing insulation that will not resoften or distort from its formed shape by heating until a destructive temperature is reached.

Thermosetting  -    Term describing insulation that will not re-soften or distort from its formed shape by heating until a destructive temperature is reached.
THHN -    Thermoplastic insulated, high heat resistant, nylon jacketed cable, 90øC dry location.
Throughput loss    In a fiber-optic coupler, the ratio of power at the throughput port to the power at the input port.
Throughput port    In a coupler in which the splitting ratio between output ports is not equal, the output port containing the greater power.
THW -    Thermoplastic insulated, heat and moisture resistant cable, 75øC dry and wet location.
THWN -    Thermoplastic insulated, heat and moisture resistant, nylon jacket cable, 75øC dry and wet location.



Time-division multiplexing

A transmission technique whereby several low speed channels are multiplexed into a high- speed channel for transmission.   Each low-speed channel is allocated a specific position based on time.

Tinning -    Tinning is divided into two types:  Electrotinned and Hot Dipped.  Electrotinned is the process of electroplating the surface of a conductor material with a tin or tin-lead alloy. Whereas, Hot Dipped is the process of pulling the conductor material through a molten bath of the tin or tinlead alloy.

Tinning.    Both ferrous and nonferrous wires can be coated by either electrolytic or hot-dip processes, and both processes are also used for coating small components.  The various processes are summarized below.
Electrolytic tinning.  There are two processes.  In one  an alkali process  the electrolyte is a solution of sodium stannate containing free caustic soda.  The other process uses an electrolyte of a stannous sulphate solution, cresol-sulphonic  acid, sulphuric acid, gelatin and beta-naphthol and also bright tin.  The weight of tin deposited in either process depends on the speed of wire travel, the current used, the size of the anode (tin) and the ratio of its surface area to that of the cathode (the steel wire) and their distance apart.
Hot tinning steel wire.  Common procedure is to clean the wire by passing it through
30 to 50 percent by volume cold hydrochloric acid at low line speeds.  Electrolytic alkaline degreasing or acid pickling is much quicker.  A typical solution for electrolytic degreasing would be 5 percent sodium hydroxide at 80 to 95 deg. C. while pickling would most often be carried out in 5 to 20 percent sulphuric acid at room temperature followed by water rinsing. A brief immersion in a flux solution is necessary before tinning.
The tinning bath temperature necessary for steel wires is from 280 to 320 deg C. After emerging from the tinning bath the wires are wiped to remove excess coating metal; this subject is discussed under the next entry for tinning copper wire.
To obtain a highly lustrous tin coating, the wires are passed through a water tank after they have been wiped, so that they are cooled quickly.  A yellowish tinge to the coat is caused by oxidation due to the tin in the bath being too hot.  It is frequently desired that the temperature of the tin bath at the point of entry of the work shall be relatively high (say, 300 deg. C.) compared with the finishing temperature (say, 250 deg. C.).  Moreover, it is good practice for the surface of the molten tin at the point of withdrawal to be free
from any active flux which may be picked up on the work and cause subsequent corrosion.
Medium grade rubber is the most widely used wiping material and is generally suitable for fine and intermediate gauge soft-wire. A precision die may also be used especially for the finer gauges or wire. Asbestos is suitable for heavy gauged wire.
Testing tinned steel wire.  It is possible to adapt the thiocyanate test used for tin-plate and the results obtained in tests on 1-meter lengths of wire have given a fair indication of the rust resistance of the wire as judged by direct corrosion tests in humid and sulphur dioxide polluted atmosphere. It has been found essential for a fair assessment in any of the tests to take samples at frequent intervals along the length of a coil of wire.
Tinning of copper wires.  Carried out in the electrical industry to prevent chemical interactions between the copper and rubber in rubber-covered  cables and to improve solderabilty.  Because it is not known at what point the copper wire or cable may have to be soldered, it is necessary to ensure good solderability throughout the whole length of the wire or cable; tinning the ends of uncoated wires where they have to soldered is very time consuming.
Copper wire for cable manufacture is usually tinned by the hot dip process, and generally the readiness with which copper reacts with molten tin allow the omission of any complex preparative treatment.  The wire is usually therefore fed directly from the
uncoiler into the fluxing tank and then into the tinning bath, with occasionally a brief
intermediate dip in cold dilute sulphuric or hydrochloric acid.  The temperature of the tinning bath need only be 260 deg. C., provided that this is sufficient to raise the heavier

wires to the tinning temperature within the immersion period.  Excess tin is usually removed by wiping between rubber blocks, but the wear of the blocks is rapid and wiping can be uneven so that a great deal depends on the skill of the operator in judging the correct amount of wiper pressure required or when to renew the rubber blocks.  For this reason the wire is sometimes passed through a diamond wiredrawing die of aperture size about 0.075 mm above the wire diameter as a more reproducible wiping method. Less expensive ceramic type dies serve equally well. A difficulty with the use of a die for wiping is that the wire may not pass centrally through the die aperture.
An alternative method is by electro-deposition,  in which the copper wire is degreased and passed through electro-plating baths, either sodium or potassium stannate, stannous sulphate, or fluoborate.  It is practicable to build up a coating comparable in thickness to a hot-dipped tin coating, say from 0.005 to 0.03 mm., but it is generally not economic to allow plating time for greater thickness to be built up.  It is also not usually economic to apply the coating as the final process, and plating is often carried out when the wire is still in the region of 2.5 mm dia., followed by drawing down and annealing by resistance heating in a steam atmosphere.  With electro-tinning there is no intervening layer of
copper-tin compounds as there is on a hot-dipped copper wire, and there is a danger that a thin electro-deposited  coating may dissolve in the molten solder leaving the wire bare of tin and almost unsolderable.
Virtually all tinned copper wire is coated in pure tin, but 60 percent tin and 40 percent lead is sometimes used; for electro-plated coatings, 30 and 40 percent tin plus lead alloys are sometimes used particularly for heavier coatings (3-5 µm.) designated for electronic component terminations.  This plating is carried out at the final wire size at low speed.
Geoffroy-Delore  process.  A method of hot-tinning a single strand of copper wire at
high speed; it can take wire direct from a continuous wiredrawing machine and a continuous annealer.  The wire receives a final sizing pass through a diamond die before passing through in-line annealing, fluxing and tinning sections.  The aperture of this die differs from the final wiping die by a known controlled amount and by altering this differential the coating thickness may be controlled accurately.  The diamond wiping die is held loosely so that it is relatively free to move in a horizontal plane either above the bath or in the surface of the tin, so ensuring concentric coatings.  Speeds of 6 to 22.5 m./sec are possible because the tension in the wire is maintained at a low controlled value by passing the wire as it enters the plant, and again after completion of tinning, around the same drive pulley.
The single stand of wire, after being drawn to size and annealed, enters a covered trough and descends into the totally enclosed pickling and fluxing cabinet below the ventilation ducts.  The excess of flux on the wire is removed centrifugally while the wire passes around pulleys, and the last traces of flux are blown off with air jets in the cabinet. The wire issues through the hood downwards into the tinning bath and emerges vertically through the diamond die in the wiping unit and then enters the tubular cooling chamber on its way to the coiler.
Tinning small components.  For hot-tinning small and intricate components, such as terminals, direct immersion in molten tin or solder followed by centrifuging, separating and quenching, gives excellent results in many cases, but when tinning brass, of which the majority of these small wares are made, the dipping bath may rather quickly become contaminated with copper and zinc. This may be mitigated, where convenient, by plating the articles with a 3 µm. coating of electro-deposited  nickel prior to hot-dipping.  The effective clearance of narrow or re-entrant configurations may be achieved by the use of high centrifuging speeds, but this may result in an unduly thin coating on the exterior surfaces.  Barrel hot-tinning , wherein the work is rotated in a heated container together with a measured quantity of molten tin or solder and flux, is satisfactory for many shapes and sizes of article.  Coatings formed by electro plating followed by melting are increasingly utilized, the process consisting of electroplating tin or tin-lead alloy to the


desired thickness followed by monetary melting of the coating in hot oil or other suitable medium.  Generally melted coatings are considered as useful alternative to hot-dipped coatings in cases where articles or components are of small size or complicated shape where there may be strict requirements for adherence to fine dimensional tolerances. Using suitable techniques, components with apertures about 0.8 mm. may be hot tinned without blockage, and threads as fine as 10 B.A. fit satisfactorily after tinning.
Tinning fluxes.  Usually a mixture of some chlorides, such as those of zinc, sodium, ammonium, potassium and stannous tin, with glycerin, lactic acid, urea or other compounds, in aqueous solution.  Zinc chloride is often avoided as it can carry over on to the finished product and cause corrosion.  The concentration of salts is normally within the range of 4.5 to 14 kg. Of solids per 45 lit. of solution.  Sometimes, simply very dilute hydrochloric acid is used.  Fatty acids have also been found suitable as fluxes and particularly mixed fatty acids containing about 65 percent, unsaturated acids, mainly oleic acid, with up to 20 percent each of palmitic and stearic acid.  Adequate fume extraction is necessary.
Tin-nickel coating.  A coating consisting of two parts of tin with one part of nickel developed by the Tin Research Institute.  Claimed to be equally as lasting and of warmer luster than chromium.
Tin-zinc coating.  Developed by the Tin Research Institute as an alternative to cadmium, this coating used as a protective coating on steel has been found to have wide applications.  It consists of three parts of tin to one of zinc.
Cleaning of tinning baths.  To purify and clean hot tinning baths, pass air through, with the tin just above its melting point until the dross formed is no longer grey.  To remove copper, dredge with a perforated ladle or stir in flowers of sulphur.
Tinsel cord.    Extra flexible cord made with tinsel conductors to give the ultimate in flexibility.  Used mostly in the communications  field on headsets, hand sets, and anywhere that repeated flexing is necessary.
Tinsel Wire    A very flexible conductor made by serving one or more very small flat conductors over a
fibrous core such as a high tenacity rayon, nylon, fortisan or cotton fibers.
Tinsel wire.    A low voltage, stranded wire where each strand is very thin copper ribbon spirally
wrapped around a textile yarn.  Insulation is generally a textile braid. Intended usage is for severe flexing.
Token ring    A ring-based network scheme in which a token is used to control access to a network.
Used by IEEE 802.5 and FDDI.
Tolerance.    The amount by which the diameter of a wire may vary above and below the stipulated size.
Torque Test    A test designed to ascertain the stiffness of a material under given environmental conditions.
Torsion test.    Wire undergoing the test must withstand the number of torsions or twists specified for that quality without fracture, splitting or other defect.  A length of wire is twisted o nits own axis in one direction until it breaks.  A definite length of the wire to be tested is held horizontally and clamped at both ends in the separate grips of the torsion machine, one set of grips being caused to revolve at a specified speed either by hand or by electric drive until fracture occurs; the other set of grips is not permitted to revolve but only to slide forward as the wire is twisted to prevent the formation of longitudinal stresses.  Some specifications do, however, call for a specified load to be applied to these sliding grips.
The number of complete revolutions or torsions before fracture is usually specified in a length 100 times the diameter of the wire, although the test piece may be of  fixed length, often 100 or 200 mm., and the number of torsions calculated to 100d.
Wire that has been overdrawn, underdrawn, or badly patented, or that has been overheated during drawing, gives low or erratic torsion results and the twisted wire may be lumpy or split along its length or the fractured end may break off and fly.  The speed of twisting must be such that the wire is not heated appreciably during the test.  The speed may be laid down in the particular specification and  60 r.p.m. is a common maximum.


Torsion test and twisting test are the same.
A second form of the test is to make up to about six revolutions in one direction, unwind and then six torsions in the opposite direction followed by unwinding.  Fracture should not occur but any surface imperfections are revealed.  See entry for reversed torsion test.
A scientific form of torsion test is used to determine modulus of rigidity, yield point
and elastic limit stresses in torsion, and shear stress.  A machined specimen is clamped at one end and a torque applied at the other end.  Values of torque and angle of twist are recorded and required values calculated.
Tough pitch copper.    Refined copper in which the oxygen content has been adjusted to between about 0.02 and
0.08 percent.  It is at least 99.5 percent pure.  Tough pitch copper having a conductivity of
100 percent. I.A.C.S. minimum is the normal material for electrical conductors of all kinds, especially wire.
Tracer Stripe    When more than one color coding stripe is required, the first, or widest, stripe is the base
stripe, the other, usually narrower stripes, being termed tracer stripes.
Tracer Stripe -    When more than one color coding stripe is required, the first (or widest) is called the base stripe, whereas the narrow stripes are termed tracer stripes.
Transducer    A device for converting energy from one form to another, such as optical energy to electrical energy.
Tree Wire -    A cable designed to be used in conjunction with insulators, for overhead distribution, having heavy covering which reduces faults due to the touching of tree limbs in heavily wooded areas.  (See spacer cable, sometimes one in the same).
Triaxial    A cable construction, having three coincident axes, such as conductor, first shield and second shield all insulated from one another.
Triaxial -    A cable construction, having three coincident axes, such as, conductor, first shield, and second shield all insulated from one another.
Trichlorethylene.    The most commonly used solvent for degreasing, it is a clear, colorless, non-inflammable liquid, boiling at 87 deg. C. The low specific heat and latent heat of volatilization make it especially useful in hot solvent and vapor degreasing plants, since it is readily raised to boiling point with a small input of heat.  Having a low surface tension it also penetrates readily into crevices, and as it is not affected by water, the contaminated solvent can be recovered by steam distillation.  Trichlorethylene  decomposes at temperatures in excess of
120 deg. to  130 deg. C., so that local overheating has to be avoided.
Triplex Cable -    A cable composed of either three insulated single-conductor  cables twisted together or two insulated single-conductor  cables twisted together with a bare conductor or messenger.
Trolley wire.    For electric traction.  Composition  hard drawn copper or hard drawn cadmium copper.
Cadmium content 0.5-1.2 percent.  Drawn to a section having a cross-sectional  area of 80 mm.2
True Concentric    A true concentric stranding or twisted cable is when each successive layer has a reversed direction of lay from the preceding layer.
True Concentric -    A true concentric stranding or twisting cable is when each successive layer has a reversed direction of lay from the preceding layer.
Tubing-on.    A method of extruding plastic material on pre-spiraled shaped conductors.  A special core is used so that the plastic and the conductor are held separate until the final forming in the die has taken place, when the tube so formed is drawn on to the conductor by adjustment of  haul-off and extruder speeds.  This type of extrusion is ideally suited to fine wires where a heavy coating is required such as that used for electrical installation and other similar insulation.  It also gives good concentricity, but adhesion is not as good as is possible with other methods.
Tubular braider.    This works on a different system to the maypole braider.  The wires or yarns are passed over and under each other by the use of deflectors, rocker arms or both.  Two and a half to


three times as fast as the maypole machine, these braiders are much quieter in operation.
Tubular strander.    A high speed stranding machine in which the stranding bobbins are mounted in floating frames along the center line of a large rotating steel tube which is cut away at intervals so that the bobbins can be inserted.  A wire from one bobbin runs through the center of the tube; the remaining wires pass long the internal periphery of the tube to the end of the machine where they are threaded through the hardened steel dies of a revolving lay plate. The wires then pass through a fixed die having an internal diameter corresponding to the external diameter of the stranded wire.
Tungsten carbide.    This is the hard constituent of cemented tungsten carbide which is used in the manufacture of cemented tungsten carbide wiredrawing dies and cutting tool tips.
Cemented tungsten carbide is prepared by milling tungsten carbide powder with cobalt metal powder in ball mills and subsequently pressing the mixed powders in dies to give the required shape.  The amount of cobalt added controls the degree of hardness of the pellet after hardening, the more cobalt the softer the insert.  Usual additions are 10 to 14 percent, though less cobalt is sometimes used.  The compacts are then pre-sintered under a protective atmosphere, after which they can be machined to the required shape.  The
shaped pieces are then sintered in an electric furnace under vacuum or in a hydrogen atmosphere to impart final hardness.  Appreciable shrinkage takes place during sintering and this must be allowed for in calculating pre-sintered dimensions.  See also entry for tungsten carbide dies under "Dies".
TW -    Thermoplastic insulated, moisture resistant cable, 60øC wet or dry location.

Twin Cable -    A cable composed of two insulated conductors laid parallel and having a common covering.
Twin Coaxial    A configuration containing two separate, complete coaxial cables laid parallel or twisted around each other in one complex.
Twining machines.    This single twist type of machine is used to twist or twin together two single wires or flexible cores.  The machine comprises a counterweighted  cradle supported with a bow frame which is capable of being rotated on trunnions around the cradle, a layplate, forming die, capstan haul-off and take-up reel.  The cradle is counter-weighted  so as to prevent its rotation within the bow frame, but the reel supported in the cradle is free to rotate on its own spindle, which it does as the wire is pulled by the capstan through the layplate and forming die.  The second spool of wire is located outside of the machine and the wire is taken from this through one of the trunnions supporting the bow, around the bow to the layplate (where the two wires are twisted together) and through the forming die.  When twining plastic insulated wire, particularly wire with a thin insulation coating, the
insulation may be damaged by rubbing on the lips of the bobbins or by the traverse guide rollers.  This is overcome in one machine in which the haul-off wheel and measuring wheel are mounted on a housing which oscillates in relation to the take-up bobbin so that the twin passes directly to the bobbin.
Twisted Pair -    A cable composed of two small insulated conductors twisted together, but having no common covering.
Twisted pair.    Two insulated conductors, twisted together and coded.
Twisting test.    Another name for the torsion test (q.v.)

Tyre cord wire.                       High tensile steel wire of 0.65-0.85 percent carbon.  Usually drawn to 0.15 mm. dia., and fabricated into cord of 7 x 3 construction.  Requires particularly clean steel and great care at all stages of manufacture.
UD -    Underground distribution.
UF -    Underground feeder cable, thermoplastic insulated 60øC wet or dry location.
UL -    Underwriters Laboratory.  Standards and tests that wire must meet in order to receive UL
approval.
Ultimate tensile strength.    The maximum load reached in a tensile test divided by the original cross-sectional  area of




Ultra Violet
Degradation

the gauge length portion of the test piece.
The degradation caused by long time exposure of a material to sunlight or other ultraviolet rays containing radiation.

Ultrasonic gauge.    A non-destructible  test instrument using the principle of ultrasonic resonance to establish the thickness of metals and plastics.  Mechanical vibrations are sent into the material under test, and the resonant frequency returning from the sample appears as two or more vertical traces on a cathode ray tube.  Suitably calibrated scales make it possible to read the thickness directly without calculation or complicated manipulation of dials.  This type of instrument can be used for quality control in the production of such items as lead sheathed cable.
Ultrasonics.    High frequency sound waves produced by transducers which convert radio frequency current to sound waves of the same frequency.  These can be used in a liquid bath to cause the constant formation and collapse of cavities in the liquid to promote or accelerate surface cleaning of material placed in the liquid.  The process is increasingly used for removing grease, etc., from components and precision parts including clearing the holes of diamond drawing dies (see entry for cleaning under die maintenance), for the descaling of wire (see entry for ultrasonic cleaning under the heading "Pickling") and for removal of lubricants (see entry for ultrasonic removal of lubricants under the heading "Lubricants");
a further use is for the agitation of the liquid in which wire is drawn to clean the wire before it enters the die to improve the drawn finish (see entry for ultrasonic agitation of drawing liquid under "Wire Drawing").  Ultrasonic energy can also be used to transmit vibrations to a drill tip for cutting holes of any shape in tungsten carbide, ceramics, etc. (See entry for ultrasonic drilling under "Die Manufacture").

Ultraviolet Degradation
-

The degradation caused by long time exposure of a material to sunlight or other ultraviolet rays containing radiation.

Underfill.    A cross-section which has not filled up the roll pass so that it is inaccurate in both shape and dimensions.

Undirectional
Conductor -

Unidirectional Concentric Stranding Unidirectional Stranding

Conductor constructed with a central core surrounded by more than one layer of heilically laid with all layers having a common direction of lay, with increase in length of lay for each successive layer.
A unidirectional stranding is where each successive layer has a different lay length thereby retaining a circular form without migration of strands from one layer to another.
A term denoting, that in a stranded conductor all layers have the same direction lay.

Unilay Conductor -    Conductor constructed with a central core surrounded by more than one layer of helically laid wires, all layers having a common length and direction of lay.
Unilay Stranding    A bunched construction having 19,27,37 or any number of strands which might be found in a concentric stranding.
Unit cable.    The most widely used type of subscribers' telephone cable, which as largely superseded the layered cable (q.v.).   Made up from paired cables on a stranding machine with the carriages rotating in the same direction to produce a very flexible cable.  50 or 100 pairs are usually assembled in this way and then bunched to form one cable, 18 units of 100 pairs for example forming an 1800 pair cable.  Easier to manufacture than layered cable, with less danger of stretching the conductors beyond their elastic limit, and enabling much smaller conductors to be used.  Conductors used in unit type subscriber cable are usually of 0.32, 0.4, 0.5 or 0.6 mm. dia.

United States steel wire gauge.

A name sometimes applied to Steel Wire Gauge (Washburn & Moen Gauge) to distinguish it from Standard Wire Gauge.

URC -    Weatherproof cable type, TBWP, DBWP as developed by the University Research
Commission.
URD -    Underground residential distribution.
USE -    Underground service entrance cable, 75øC wet location.
V -    Varnished cambric, 85øC dry location.




Velocity of
Propagation

In cable measurements,  a function of dielectric constant.  The transmission speed of an electrical signal down a length of cable compared to speed in free space - expressed as a percentage of speed in free space.

Vibration-free  conductor.     For overhead lines when a steel cored aluminum conductor is manufactured so that the aluminum "sheath" fits very loosely over the steel core, it is considered that as each tends to carry its load independently and the two metals  have different elastic moduli the vibrations in each are on a different harmonic and damp each other out.

VIP -    Vulcanized interlinked polyethylene.
Viscous    Thick - Resistant to flow.  Applied to a liquid.
Volt    A unit of electromotive force.
Volt -    A unit of electromotive force.  It is the difference in potential required to produce a current of one ampere through one ohm of resistance.
Voltage Drop    A term expressing the amount of voltage loss from original input in a conductor of given size and length.
Voltage Drop -    A term expressing the amount of voltage loss from original input in a conductor of given size and length.

Voltage Standing
Wave Ratio

The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of a mismatched radio frequency transmission line.

Voltage Stress    The stress found within a material when subjected to an electrical charge.
Volume Resistivity    The volume resistance between two electrodes of unit area and unit distance apart that are in contact with, or imbedded in, a specimen, is the ratio of the direct voltage applied to the electrodes to that portion of the current between them that is distributed through the volume of the specimen.  Usually expressed in ohms/centimeter.
Vulcanization.    The process of extruding on a wire, under high pressure a uniform seamless, close fitting tube of a rubber or rubber like compound. The covered wire then continues into a vulcanizing chamber, where, under high pressure and temperature control, the insulation is vulcanized continuously.
Vulcanizing.    Se entry for rubber insulation.
W/G -    With ground.
W/O/G -    Without ground.
Wall Thickness    A term expressing the thickness of a layer of applied insulation or jacket.
Wall Thickness -    A term used expressing the thickness of a layer of applied insulation or jacket.
Warrington.    A strand construction in which one layer of wires, usually the outer, is composed of alternating large and small wires.
Water Absorption Test    A method to determine the water absorbed through an insulating material after a given water immersion period.

Water Absorption Test
-

A method to determine the water absorbed through an insulating material after a given water immersion period.

Waterblocked Cable    A cable specially constructed with no internal voids in order to allow no longitudinal water passage under a given pressure.
Watt    A unit of electrical power; the power of one ampere of current pushed by one volt of electromotive force.
Watt -    An electrical unit representing power.  One watt is the amount of power dissipated, as heat, when a current of one ampere flows through one ohm of resistance.
Wave Length    The distance, measured in the direction of propagation, of a repetitive electrical pulse or waveform between two successive points that are characterized by the same phase of vibration.
Wavelength    The distance between the same two points on adjacent waves; the time required for a wave to complete a single cycle.

Wavelength-division multiplexing

A transmission technique by which separate optical channels, distinguished by wavelength, are multiplexed onto an optical fiber for transmission.


WDM    Wavelength-division multiplexing.
Welding machines.    See descriptions of the various types of welding processes under "Welding", the majority of these processes requiring a machine designed to suit that process.
Machine setting.  A table of proved weld settings should be consulted to obtain the recommended  secondary current, electrode force, and weld period figures for the specific gauge of wire to be joined.  If the metal to be worked is heavily mill-scaled or dirty and it is not proposed to remove this, due allowance must be made in the final setting figures. The electrode force must be increased, maybe 10 percent or 20 percent above the recommended pressure to break down the surface oxides and the welding current stepped up a small amount.  On the air or hydraulically operated welder, pressure is adjusted on a pressure gauge to the stipulated value, although it is often the case that this instrument registers unit pressure in kg./mm.2 or lb./in.2 and not total load on the electrode tips.
kVa Rating.  Modern spot or projection welders are assessed on a basis of a nominal rating, representing 50 percent of the maximum kVa, when the machine is et to the limit of the transformer output.  This takes into account the high instantaneous current loading of
an intermittent nature, for the machine working duty cycle is often less than 10 percent and thus the heating effect on the distribution system is very small.  The main purpose of nominal kVa rating is to convey to the installation engineer information from which he can calculate the size of feeder, isolating switch-fuse, etc., he must make available for a given size of machine.  A machine with a low duty cycle, having a nameplate rating of 25 kVa, can draw a maximum instantaneous demand of 50 kVa from the electrical supply, but can be installed where a load of only 25 kVa, can be drawn under continuous conditions.  The relationship of secondary current or welding output to the kVa rating is dependent on
many factors, but is principally governed by the area surrounded by the arms of the machine or the secondary loop.  The greater the gap or throat dimensions in the secondary circuit, the higher will be the impedance and therefore the voltage  must be stepped up for a given current to flow.
Welding electrode.  See "Electrode".
Welding.    Forming a union between metals, the surfaces of which have been reduced to a plastic or liquid condition by heating, with or without added metal, and with or without the application of pressure.
In electric welding, the two metals to be united are placed in contact and a powerful electric current is passed through them.  The high resistance of the metal junction, because of the poor contact, creates intense heat, which welds the metals together.  The weld metal is the whole of the metal which has been melted in a fusion weld.  By resistance welding standards, a steel is usually termed low carbon or mild steel when the carbon content does not exceed 0.20 percent, and there are no other alloying elements or high percentage of impurities.  Even this moderate percentage of carbon gives rise to brittle welds and it is advisable to utilize a softer wire if possible.  A mild drawn steel wire of the following percentage analysis give extremely ductile and consistent welding results: carbon .07 to
.11; sulphur .05 max.; phosphorus .05 max.; silicon a trace; and manganese .3 to .55.
The most important factors which determine the final welding result are the type of material, the condition of the surface, the diameter of the wire, the welding current, the welding time and the electrode force.
Arc.  Welding by means of an electric arc formed between the electrode and the metal being welded.
Butt.  Welding of two wires end to end particularly to allow continuous drawing from one coil of wire to another.  A recent investigation has shown that the quality of the weld in a high carbon wire depends to a large extent on the skill of the operator, the heat
treatment cycle necessary to anneal the welded section being judged by visual examination which could be affected by the lighting conditions.   Some difficulty is experienced with weld breaks when drawing fine higher carbon grades, and the resultant re-threading of the drawing machine wastes valuable machine time.  It has been found that the majority of


breaks occurred in a fine grain region at the end heat affected zone formed during the conventional annealing cycle, whereas if the full anneal is followed by a low temperature tempering cycle the fine grain region is eliminated.  A semi-automatic  welder with controlled welding, heat treatment and cooling cycles has also been found to make end preparations and selection of heat treatment conditions less critical.
Cold pressure. A method of jointing aluminum or copper wires and sheets by bringing the scrupulously clean wire brushed surfaces of the parts into contact and pressing them together with considerable deformation.  A perfect metallurgical bond can be achieved
with or without applied heat.  Tools have been developed for butt-welding of wires and the technique is successfully used for making electrical joints in wire and strip.
Cross wire.  A point contact is provided by the natural incidence of the two wires, and consequently a localized area offers high resistance to the flow of welding current.  This type of joint, therefore, represents a principle of projection welding.  The interfaces rapidly reach welding heat, and mechanical pressure is available to forge the joint into a homogeneous weld with a strength factor comparable to the parent material.  See next entry for fabric welding.
Fabric welding.  Production of fabric in large panels or rolls can only be profitably operated by the use of high speed special purpose machines, capable of running continuously with a minimum of supervision.  Such equipment can be broken down into three or possibly four pieces of mechanism: (1) straightening and guiding of main wires, (2) straightening,  guiding and maybe cropping to the length of cross wires, (3) a machine for welding areas and indexing gear for holding the cross wire pitch, (4) a weld counter, mat guillotine or power operated spool for the completed fabric.
Flash butt.  Resistance welding in which the components are brought lightly together after the voltage has been applied so that sparking and local arcing take place, heating the contact areas progressively and burning off portions of them. When the whole surface is thus brought up to the welding temperature, the weld is made by forcing the parts together.
It is claimed that flash welding gives higher weld strength, that it is not so important to
prepare the ends for welding and that there is a smaller flash burr or upset.
One purpose for which this process is used is for welding on wire coils for continuous drawing.  It has also been used for welding together 250 kg. coils into 1 ton coils at the rod stage before heat treatment and cleaning.
Friction.  One of the two components to be welded is rotated while being pressed against the other.  Heat is generated by the friction of the abutting faces, and at an appropriate moment the rotated component is braked and additional pressure applied through the axis of the other component to consolidate the joint.  When applied to joining of rod or wire coils for drawing, it is proposed that a short length of the rod or wire would be rotated between them to produce two welds close together, the quality of the welds being such as to offset any disadvantages of an additional weld.  Micro friction welding apparatus has been developed for welding wires down to 0.76 mm dia., particularly important for joining dissimilar material; hard and soft materials successfully joined include nickel/iron, nickel/aluminum  and copper/nickel chrome.
Fusion.  Any welding process in which the weld is made without mechanical pressure.
Multiple spot.  Spot welding in which a number of spot welds are carried out simultaneously by fitting bar electrodes, usually limited to 150 mm in length as there is a tendency for the extremities to defect, thus causing uneven pressure distribution.  The tee shaped electrode is usually profiled out of hard drawn high conductivity copper bar and the taper which may be 19 or 25 mm wide 5 deg inclusive is machined and the cooling water holes drilled and plugged where necessary.  It is easier to complete welds in single rows when using taper seating electrodes not mounted on substantial bolsters and platens, rather than in rectangular patterns, as the electrode faces have only to be aligned in one plane and not two as in the latter case.
Projection.  Resistance welding in which one or more areas of contact, in the form of

projections, are made in the components before welding and which a number of welds may thus be made simultaneously be means of projection welding dies.
Since current and pressure are automatically concentrated at the welding points when welding a number of cross wires together, the electrodes only transfer the current and pressure as opposed to spot welding where the necessary concentration is obtained by special shaping of the electrodes; cross wire welding is therefore an example of projection welding.  A characteristic of projection welding is that a certain setdown takes place during welding, and this makes possible automatic distribution of current and pressure to
several welding points simultaneously;  it is not unusual to make 10 to 50 welds at one time with one pair of electrodes.
Resistance.  Implies passing a heavy current for a certain period through two or more metal components squeezed together by a substantial pressure.  Heat is generated by the electrical resistance of the work-pieces to the passage of this current and they are forged together to forma weld without the addition of filler metal.
Seam.  The parts to be welded are overlapped and gripped between circular electrode wheels or between a bar and a wheel.
Series.  Welding in which the current is allowed to flow through approximately one half of the wire joints via a copper back-up block and through the balance of wires in contact to complete the circuit.  This enables every pair of welds to be completed for only a little more than the current required when direct welding single joints.  For a given size of transformer, the welding capacity is the same for machines having 300, 600, 900 mm., throat dimensions, etc.  The capital cost of a long throated machine is not therefore much in excess of a welder having less clearance but the same welding capacity.
The wires resting immediately on the lower electrode dies, which are split in the center and connected to each end of the welding transformer secondary turn, must run parallel to this division.  If the lower wires were inadvertently positioned laterally across the secondary conductors, the lower wires only would take place.  The over number of joints being welded on one platen must be not less than 85 percent of the total on the other in the case of light gauges, or one group of welds will be overheated or conversely fall to attain welding temperatures.  The factor for relative platen loadings is proportionately reduced as the gauges of wire increase.  Diameters grater than 4 mm should be welded under
equalized platen conditions.  It is also quite practical to series weld different gauges of main and cross wire within the usual limits employed on direct welding to ensure correct heat balance.
Spot. Welding at a closely defined spot. Accomplished  by holding together the parts to be welded under mechanical pressure between two electrodes, though which a current is passed for a pre-set period.
Wet drawn wire.    Wire drawn through a liquid lubricant to give a bright polished finish.  Wire required with a wet drawn finish is not necessarily wet drawn all the way from the soft condition to finished size.  In the case of galvanized wires, copper, bras or bronze coated wires, and some classes of bright wire this can be done if machinery is available to give the required reduction or area.  Where a fully coppered coat is required, a much heavier coat must be used before drawing, or the final wet reduction must not exceed 30 percent RA after coppering.  With bright wire, if no discoloration is permitted, the degree of wet drawing is limited by the necessary lack of coating and weakness of lubricant to about 20 percent R.A.  According to the tensile requirements in the finished wire the gap which may exist between the size at which the wire is heat-treated and the size at which wet drawing can commence, has to be bridged by dry drawing.  Any soap or similar deposits on the wire must then be removed during the preparations before the final wet drawing.  Immersion in boiling soda ash is one way of doing this.
Wetting    The ability of a material to absorb moisture.
Wetting -    The ability of a material to absorb moisture.


Wetting agent.    A product added to the pickling solution which causes the surface of the pickled metal to be simultaneously and uniformly moistened so enabling the acid to work more evenly and quickly.
Wicking    The longitudinal flow of a liquid in a wire or cable construction due to capillary action.
Windability.    A term, usually applied to copper winding wires, which implies good elongation, flexibility, abrasion resistance and lubrication.
Winding helical coils.    The length of wire required for an element and the space it will require when close- spiraled may be obtained from the following formula:

L    25/1000    π (m ⋅ d)
L= length in meters of a 25 mm long close coils. d = diameter of wire in mm.
m = diameter of mandrel in mm.

Tables are available from which space a known length of wire will occupy when close- spiraled may be easily obtained for all common mandrel sizes.
Winding machines.    Used to wind a perfect bobbin quickly, being fitted with a traversing mechanism for this purpose. Machines are available to wind all sizes of wire from the heaviest wire ropes on cable take-up units to the very finest wires on coil winding machines.  Most designs employ a mechanical device to operate the traverse mechanism, for example, a uniform motion cam or screw-shaft with engaging nut, the various lays being obtained by means of a gear box or change wheels.
Winding wires.    Single round or rectangular conductors used for winding a large proportion of rotary and static electrical equipment ranging from large motors and transformers to small relays. Insulation may be of paper, fiber glass, asbestos, cotton or enamel.  Both copper and aluminum wires are used see entries for enameling and for ceramic coating.
Winding.    A general term applied to an assemblage of insulated conductors forming part of a machine, transformer, or piece of apparatus, and intended either to produce a magnetic field or to be acted upon thereby.
Wire    (1) A single piece of slender, flexible metal ranging in approximate size from a piece that
is difficult to bend by hand to a fine thread. (2) Several wires as in (1) twisted together  (3) Wires as in (1) or (2) insulated.
Wire -    Wire can be divided into two areas:  (1) a slender rod or filament of drawn metal, (2) a rod of drawn metal filament covered with insulation.  These can be classified as drawn metal wire and insulated wire respectively.
Wire diameter.    Can be verified by weighting a given length of wire, the specific weight of which is exactly known.  The diameter is then found from:

D =  4W/LxS.W. x π    (Note: a symbol omitted -not avail.)

where D = diameter of the wire; W = weight of the wire; S.W. specific weight; and L =
length of the wire.
Wire drawing dies.    See entries under "Die"
Wire drawing machines.    Nearly all wire drawing machines are basically a number of power-driven capstans which draw the wire through the dies.  These are arranged in sequence with speeds to suit the elongation of the wire at each reduction.  There are three basic types - with capstans running at exactly the same speed as the wire, with capstans running faster than the wire allowing the wire to "slip", and accumulation machines which collect more wire on each block than is necessary to feed the following reduction.  "Slip" machines are used for nonferrous wires and finer sizes in ferrous and alloy wires.  Machines and capstans at synchronous speeds are necessarily expensive in design due to complicated electrical controls.  Accumulation machines have better cooling properties due to storage on each block and have more flexibility for production on intermediate blocks.


There are many points to be kept in mind when choosing the appropriate drawing machine for a particular duty, and usually it is a matter of compromise between the various factors to get as near as possible to the ideal.  For rod sizes over 6 mm dia. Handling problems on accumulation machines become sever.  Higher speeds are possible with pickled rods than with mechanically descaled rods because they are easier to lubricate. Overhead take-off units may not be sufficiently fast in the later stages of the machine; on the other hand one man can operate a number of slower machines.  When cooling is important for quality reasons, accumulation machines operate under very cool conditions because of the long length of wire stored between dies, but modern machines of other
types are equally efficient in cooling.
High carbon wires are now often drawn with relatively small reductions per die to limit temperature rise, whereas low carbon wires are reduced as rapidly as possible.  Short runs are more readily produced on tension arm and back-pull machines owing to the shorter threading time and the small amount of wire in the machine at any one time.
A.C. machines are cheapest, particularly if a motor of the same power is fitted to each block for standardization,  but since the power demand increases to the finishing block if level drafting is used, the motor power n this block limits machine output; by employing taper drafting and adjusting the area reduction throughout the machine, motor loads are evened and a greater output is achieved.  Choice of ancillary equipment, and particularly choice of coiling equipment, can considerably influence the type of drawing machine chosen for a particular duty.
Accumulation type.  Drawing machines in which each block is made to run at a speed a little higher than would be necessary to supply exactly the amount of wire called for by its succeeding block , so that the amount on each block slowly accumulates.  On A.C. driven machines in practice this is achieved by arranging the drafting such that the elongation between drafts is slightly larger than the speed difference between blocks.  Each block is,
in fact, a separate machine drawing wire through a die and coiling it up.  By means of the waffle arm (q.v.) wire can be picked up from the running block and transferred to its succeeding block, where it is drawn and coiled through the next die in the series, and so on until the final block is reached.
When the accumulation of wire on any block becomes too great, this block and all the
preceding blocks are stopped and not started again until the excess wire has been drawn from it by its succeeding block, when it is again started.  These machines have the great advantage that a wide variation of die reductions can be used on them without the need for complicated and expensive gear automatically controlling the speed through each die to line up exactly with the elongation of the wire passing through it.
There are disadvantages however, particularly when the wire has a high tensile strength to start with, owing to the difficulty of manipulating this stiff wire over a number of comparatively small pulley.  They take a long time to thread up before they can produce the finished wire on the last block owing to the quite considerable amount of wire carried on each block.  They are not satisfactory at finishing speeds in excess of about
760m./min., owing to the difficulty of unwinding the wire turn by turn from each block by the waffling apparatus, and lastly, they can be dangerous should the wire break while running at a high speed.  The difficulty over finishing speed is sometimes overcome by using overhead take-off blocks for the first three or four reductions, where this type is very suitable for large sizes, and then using double blocks for the remainder.
Bull block.  A single-hold wire drawing machine of very heavy construction capable of drawing all sizes or rods between 29 and 9 mm dia.  Also used for drawing shaped wire and certain materials which need intermediate annealing after only a few drafts.  Usually provided with a single die box, but sometimes provided with an additional capstan to produce a double draft.
Double block.  The double block consists of a second block mounted above the drawing block and on the same spindle, the drawing block being keyed to the spindle but


the upper block being free to rotate on the spindle in either direction.  The accumulated wire is stored on both blocks, a pulley transferring wire from the lower to the upper block operating in a similar way to the wapping off pulley on an overhead takeoff machine.  This provides an accumulations type drawing machine which eliminates the axial twist in the wire as it is removed from one block to another tangentially and most usually as occurs on the overhead takeoff type of machine.
With this design, it is possible to stop one block in the middle of the machine and keep all others running until the stored wire on the stopped block is run down.  Also, if the last block is set to run at the maximum speed at which the wire can be drawn, and a spooler or block for coiling the wire is fitted, then by spooling or coiling at a speed greater than the maximum drawing speed, the finished wire can be removed from the machine while it is drawing and accumulating wire at maximum drawing speed, provided this speed is moderate, or the spooled weight is low.  Very difficult to achieve in practice.
The double block system is not so convenient for large sizes at the in going end of a wire drawing machine, and this is overcome in some machines designed for large inlet sizes by using overhead take-off blocks or straight through type blocks for the first few reductions and double blocks for remainder.
Morgan-Connor  type.  An accumulation type of non-slip machine in which each block is surmounted by pillars carrying a circular cp.  Wire for each block is uncoiled rather than unwound from the top of the loose coil on the preceding block, passed down the center spindle, and via pulleys the wire is directed upwards to the next die-box.  This design avoids a lot of mechanical parts and overhead structure.  Intermediate preceding blocks
can be stopped by means of a clutch to reduce the accumulation of wire while the subsequent blocks continue to draw.
Non-slip type.   Drawing machines in which the capstans run at exactly the same speed as the wire being drawn.  Used with plastic or non-liquid lubricants such as dry soap, wax, tallow, thick grease or graphite.  Generally for ferrous wire drawing.  Basically, a continuous machine of this type consists of a finishing block and a number of drawing capstans or cones in line with this.  The dies are placed before the first capstan, between each capstan and before the block.  A box usually integral with the die holder is fitted in front of each die to contain soap or other dry lubricant, and all dies are water cooled.  The wire passes through the first soap box and die, round the first capstan a number of times, through the second box and die, round the second capstan, and so on until it reaches the finishing block.  The same weight of wire is produced at each capstan as the weight fed into the machine, and since the length of the wire increases at each die as its diameter is reduced, successive capstans are run at increasing speeds.
With D.C. drives, the speed of each capstan can be varied to match variations in die diameter, and full power and speed can be used corresponding to wire load.  With  the less expensive A.C. drive, each capstan is limited to its predetermined  speed and die tolerances have to be watched to see that each capstan takes on slightly more wire than is required by the next capstan, the surplus building up on each capstan.  Each capstan is usually driven by a separate motor and a good deal of floor space is needed for multi-hole machines.
Non-slip machines of the accumulation type with individual motor drives using simple electrical control gear, are consequently much cheaper and have the advantage of better cooling facilities between reductions.  Later machines of the double block types have the advantage of producing wire without twist between reductions.
Automatic systems have been developed to control A.C. driven blocks.  By passing the wire between calipers on its passage from one block to the next die, as the block fills with wire, the wire eventually touches the top finger of  the caliper and that block is stopped. The wire level then falls until the wire contacts the lower finger of the caliper when the block is re-started.  Two contact buttons let into the block itself can be arranged to work on a similar principle - when the top button is covered the block stops, and when the bottom button is exposed the block restarts.


Overhead take-off type.  Drawing machines of the accumulation type (described elsewhere in this wire drawing machine section) in which a succession of pulleys are mounted  on a framework above the machine, wire passing from the die round a block, over an overhead pulley via a pulley on the waffle arm (q.v.) and on to the next die.  A twist is thus imparted to the wire between each reduction.  This difficulty is accentuated if for any reason one block of the machine has to be stopped  for example when it is full. In this case all preceding blocks must also be stopped and where machines are equipped with an automatic control to stop full blocks this control also stops the preceding blocks. With double blocks only the full block need be stopped.
Pre-drawer. A drawer unit placed directly ahead of cold heading or other processing
equipment to draw wire to close tolerance from rod and feed it to the processing machine. The drawing operation is often synchronized with the header so that operation is automatic even with intermittent feeding, as a small loop in the wire takes up the waiting time, allowing  the pre-drawer to run continuously, thus avoiding stop marks on the pre-drawn wire.  Many wire diameters can be drawn from only a few basic rod sizes so reducing
stock which must be carried, saving space and freeing working capital.  As the material is fed warm into the production machines, cleaner products, increased tool life and higher tensile strengths are claimed.
Slip type.  Wet-drawing multi-hole machines in which no attempt is made to align the speed of the capstan exactly to match the speed of the wire.  They are driven faster than the wire, which skids on them, relying upon the lubricating qualities of the drawing liquor and the surface hardness of the capstans to avid undue abrasion and wear.  Only two or three turns of wire are taken round each drawing capstan, the final tension being sufficient to maintain a reasonably tight wire through the machine; consequently,  they operate with varying degrees of back pull which cannot be under much control.  For this reason, the reduction in area per die is less than that normally used on non-slip machines to give a reasonable margin between die pull and wire breaking load so as to avoid wire breaks, which are expensive.  More dies and more capstans are required, but this does not matter much on slip machines.  It does not increase their cost to any appreciable extent as the capstans are grouped together on shafts each carrying four or five.  The whole assembly is driven by one motor.
Dies are situated in sockets along an arm between the capstan assemblies, except for the first and last dies.  Lubricant from a tank is pumped so as to spray on to the dies and capstans, and also, or alternatively, the capstans run in the lubricant, which also acts as a coolant.  The first die is outside the machine and in a box in which a dry lubricant can be used.  From the first die the wire enters the machine and is passed two or three times round the first capstan on the left-hand assembly, then through the first die on the die arm and
two or three times round the first capstan on the right-hand assembly, and so on until reaching the finishing block or capstan.
Experiments on increasing die life in copper wire drawing have suggested that the "suds" solution used as both lubricant and coolant is rather a poor lubricant and coolant is rather a poor lubricant for the dies and that changes in the design of copper wire drawing machines to separate the lubricant and cooling functions might be an advantage.  When a small separate quantity of lubricant is used to lubricate the final die it is possible to keep this clean much more readily than the main body of the water-oil coolant and lubricant; there is less metallic debris and the wire emerges exceptionally clean.
To provide the necessary circumferential  speed to line up approximately with the die elongation, the capstans on each shaft are arranged in diameter steps.  The thickest end of the wire must pass over the smallest steps, as these are the ones with the slowest surface speed, which can be a serious disadvantage.   Used mainly for nonferrous wires, but also for fine ferrous wires.  Slip machines are cheaper than the non-slip type but they are more expensive in production materials and engineering maintenance.
Straight-line machines.  Those in which the wire takes the shortest path from one die


round the block, and straight into the next die.  While the machine is being threaded up the torque developed by each motor is adjusted until it is just sufficient to pull the wire
through the die and in addition to provide a little extra pull through the wire itself to assist in turning the preceding capstan.  This extra pull is back pull, ensuring that the wire passes straight into each die, which is an important consideration,  especially when drawing thick wires.  To assist in avoiding any deviation from straightness in the wire as it passes
through the die from one capstan to the next, the capstans are tilted in the direction of drawing to enable a substantial number of turns to be taken around each one and to permit the wire to turn through the die to the bottom of the following capstan in a straight line.
Tandem machines.  Wire drawing machines arranged with two or more dies in succession.  The capstans drawing the wire through each die are arranged to increase in speed to correspond with the elongation of the wire.  This speed increase may be approximate, in which case the wire is made to slip on the capstans.
Wire drawing reels.    See entries for reels.
Wire drawing speed.    High production speeds are dependent upon several factors  lubrication, shape of dies, efficiency of welds, rods, cooling of wire, specification of wire, handling facilities, methods of stripping, control of cleaning and feeding stock into machines.  The speed of the machine itself is the least difficult of the problems, efficiency being dependent upon the efficient control of the variable factors.  D.C. motored equipment is more flexible, but A.C. is less expensive.  A.C. double-wound motors giving two alternative speeds are
useful when difficult conditions arise due to bad rods and other factors.  Speeds are limited when hot rolled rods are flipped off due to danger of tangles and breakages.

Wire drawing stepped cones.



Wire drawing temperature.

Virtually a number of drawing capstans mounted on one shaft decreasing in size from the
outside one.  Cones should be of very hard material, ground and highly polished.  Some machines are equipped with cone rings, easily replaceable when worn. A recent development is to make these cones or the rings in alumina ceramic as described in the entry for ceramic drawing cones.
Ductility of carbon steel wire can decrease considerably as a result of strain aging if wire temperature is not kept down. For example temperature must not exceed 160 deg. C. when drawing 4.4 mm dia. patented 0.75 percent carbon steel wire.  Since a temperature rise of
120 deg. C. per pass can be expected when using reductions of 20 percent, effective
interpass cooling is essential, especially as the drawing machines used generally have very little wire accumulation the block.
The temperature of the wire during drawing can be reduced by various methods - by water cooling of the die, by an air jet, or by air or water cooling of the capstan.  By plating the internal capstan walls to prevent corrosion, and using a chemically treated recirculating water supply system, machine productivity can be greatly increased.  More effective cooling can be obtained by ensuring that a greater proportion of the internal capstan
surface is wetted.  In the B.I.S.R.A. "narrow gap" capstan, the cooling water passes through an annular gap between the drawing ring and the stationary inner cylinder, ensuring a maximum wetted area of capstan wall at all flow rates.  However even with rust inhibited recirculating water systems, the interior of the blocks can acquire a deposit of scale and this possibility can cause such variations in cooling conditions that continuous temperature monitoring is necessary to ensure that overheating of the wire is prevented. Wire drawing speed itself does not appear to have a marked effect on temperature rise, but since it gives less time to dissipate the heat between drafts, the heat builds up.
The most successful solution appears to be direct water spray cooling of the wire by means of a cooling ring around every block, together with a rubber squeegee wipe and a compressed air wipe to make sure the wire is dry before it reaches the next die.  Or by using the direct cooling method.

Wire drawing.    Pulling wire at normal temperature through a die in order to reduce the cross-sectional
area to a required size.  Since the wire is deformed plastically in the die because of the pull exerted on it and the taper of the die, there is a limit to the reduction which can be made at


one die, according to the amount of pull the wire can withstand without breaking.  The physical properties of all metals are altered by cold drawing, so that the end properties required are obtained by matching the drawing program to the state of the initial material and the rate at which this is changed by cold work.  In addition, the desired properties can be induced by heat-treatment after part of all of the drawing is completed.
Back-pull wire drawing.  The application of a back-pull to wire before passing through the die to reduce the compressive stresses caused by the nip of the die.  The back pull cannot be increased beyond the point where the tensile stress due to the drawing force equals the tensile strength of the wire at the die exit.
Dry wire drawing.  Drawing in which soap powders or grease are used as lubricants and the wire is lapped round the capstans a sufficient number of times to ensure that no slip occurs.  The lubricant is placed in a container in front of the die and picked up by the moving wire as it passes through.  Usually used for non-slip machines drawing ferrous wire above about 0.61 mm dia.
Hot wire drawing.  Employed in the drawing of tungsten wire where heat is applied to the wire prior to its entry into the die.
Reactive wire drawing.  An alternative term for back-pull wire drawing, the name coming from the fact that in some cases the back-pull is obtained by differential gearing interposed between the pull block and the pull-back block.
Wet wire drawing.  Drawing of wire while immersed in a liquid lubricant bath containing soap solution, oil or soluble oil.  Carried out on slip machines, usually for nonferrous wire, and also for ferrous wire finer than about 0.92 mm dia.  The wire and dies on wet-drawing machines can be more easily cooled, permitting highest speeds.
Ultrasonic agitation of drawing liquid.  It has been suggested that the use of ultrasonic energy to produce cavitation in the drawing liquid produced a very smooth surface in the drawn wire by keeping particles suspended in the liquid and preventing them from collecting in the entry area of the dies where they may score the wire as it is drawn. However subsequent investigations have raised considerable doubts as to whether this process is economically worthwhile in many cases.
Ultrasonic vibration of drawing dies.  This has been claimed to reduce the drawing force when drawing both ferrous and nonferrous wire, but it has been found that this only appears to occur low speeds while local heating and breakage of the wire is likely when drawing very slowly.  It seems unlikely that oscillatory activation of the wire during drawing of thin wire will be a commercial proposition.  In drawing heavy wire and wire in difficult metals, where drawing speeds are lower, assessment of its potentialities requires further investigations to decide the most advantageous method of application and the best frequencies of oscillation.
Wire extrusion.    Name given to a hydrostatic extrusion process (q.v.) in which material to be drawn and the reel on which it is wound are mounted within a pressure vessel containing pressurized fluid.  One end of the wire is placed in a die through which it is forced out of the container by the pressurized fluid.  This wire extrusion process is similar to wire drawing with the
considerable advantage that the reduction per pass is not limited by the strength of the wire to about 20-30 percent.  In wire extrusion the limitation is the pressure in the container and with aluminum, for example, reductions of area of 99.5 percent can be obtained.  Although there are problems in controlling the stored energy which may build up in the compressed liquid.  This process appears to warrant further experimentation  to develop a process for
the forming of wire in the soft and in the hard brittle materials, as well as in the production of fine wires in a range of metals.  A combination of wire extrusion and the extrusion of composite billets can be used for the cladding wire.  The material to be clad is in the form of a billet placed inside a tube of the cladding  material, the whole placed inside the pressure chamber.  This composite billet is then extruded to give a clad product.
Wire gauge.    A device for determining the gauge number of a wire (or sheet).  A flat piece of metal pierced with holes of the appropriate size for each gauge, in which wire may be inserted to


confirm the size.  For very fine wires, the diameter is often measured by weighing  a specific length of the wire; this gives only the average cross section.  More accurate measurement is obtained by measuring the electric resistivity of the wire or by measuring the greatly enlarged shadow area.  Wire sizes are increasingly stated as a diameter measurement in millimeters.
Wire rod.    Produced from a billet by passing when hot through a series of rolls by which it is reduced in cress-sectional area and consequently elongated and formed into a finished coil.  It is
the semi finished product from which wire is made, and is generally about 5.5 mm dia to
18 mm dia.  Nonferrous rod production is discussed under the entry for copper wire rod.
The higher alloy and stainless qualities of ferrous wire are rolled in semi-continuous mills, but qualities up to at least 0.85 percent carbon are regularly rolled in continuous mills.  The latest mills have four strands and weekly outputs of over 10 thousand tons at finishing speeds up to 3650 m per minute on 5.5 mm rod, producing coils of 1400 kg in coils of 1270 mm outside dia and 800 mm inside dia.  Usual tolerances are 0.25 mm on dia and ovality.  An oval-round pass sequence is usually preferred to oval-square although this is dependent on the number of stands and the reduction required.  In general slightly
lighter reductions are necessary, this together with less stock twisting can give a better product.  The no-twist mill reverts to the original principle of alternate horizontal and vertical rolls for the finishing train, which is replaced by single strand assemblies more like machines than a succession of roll stands.  Higher finishing speed, larger reduction and quicker roll changes are possible with smaller diameter rolls which are fitted with
tungsten carbide shells to give better rod surfaces, closer tolerance and longer maintenance of pass shape.
There is increasing realization of the importance of controlled cooling to influence both the structure of the steel and the type and quality of scale on the rod.  Water cooling is
now commonly used and controls are provided to avoid excessive cooling of the surface and to permit variation of the cooling intensity to suit the type of material and the required final product.  Loop layering onto a conveyor belt to provide neat uniform loops is a satisfactory method for slow air cooling and results in compact rod coils.
Wire rod defects.  Faults in the cast products or the rolled rod are very often the original cause of defects in the finished wire.  Cold shuts, sloppy edges, and bad sets in horizontal-cast  wirebars, as well as internal unsoundness in vertical-cast materials, give rise to defects in the wire, which mostly take the form of long slivers.  In the course of hot rolling, the principal fault to guard against is the production of fins at any stage due to bad roll settings, as these develop laps, giving rise to wire products with deep line defects and,
therefor, possessing poor ductility.  Guide settings are also important, and if conditions are not perfect it is possible to obtain an accumulation of metal which periodically breaks
away as comparatively large particles which are rolled into the rod.  The rolling-in of refractory or other foreign material, e.g. from wire-bar pre-heating furnace roofs is another defect.  It has been proved that such material can be one of the most frequent causes of wire breakage on drawing, and in some cases, where the rolled-in material is of a fine siliceous nature, extremely rapid die wear results.  Electromagnetic  testing equipment has been developed for continuous indication of cracks, inclusions, laminations, etc. in hot rolled rod; it operates between the last stand and the coiler.
Diameter measurement.   Demand for close tolerance rod can better be met by continuous measurements of the rod during rolling and several non-contact instruments are now available for this purpose, accuracies quoted are of the order of 0.5 mm.
Wire rod coil compressor.  A machine which receives loosely bound coils as they leave the rolling mill and compresses and straps them in closely compact bundles to customer requirements to facilitate handling.
Wire rod storage.  There is an increasing tendency to store rods under cover and since this requires a considerable floor area if different qualities and sizes are to be sufficiently separated for easy access, a number of manufacturers have adopted the use of tiered racks


served by boom trucks.
Wire rope.    Made up of a number of strands, each strand consisting of a number of wires laid together in such a way that each wire holds its place in the strand.  The strands are then made up into a rope in the same way.  By varying the construction, that is the number, tensile strength and size of wires in a strand, number of strands in a rope, and the arrangement of wires in the strand and strands in the rope, the properties of the finished rope can be varied within wide limits to suit a particular end use.  See entries for strand and rope wire.  Some of the commoner types of rope are defined below.
Albert lay.  Another name for Lang's lay (q.v.).
Black.  Wire rope made of wires that are not coated with zinc or tin.
Bright.  Steel rope formed from bright wire (q.v.) that has not been coated.
Cable-laid.  A type of wire rope consisting of several wire ropes laid into a single wire rope, as for example 16 x 6 x 7 tiller rope.
Coal cutter. See entry under Dyform strand for details of coal cutter rope made up from this strand.
Coarse laid.  Rope formed from large wires.  Also known as hard laid rope.
Equal lay.  Wire rope in which all layers of wires have the same pitch or length of lay. Each wire in each layer therefore lies either in a bed formed by the interstices or valleys between the wires of an underlayer or alternatively along the crown of an underlying wire. On no occasion does a wire cross over the crowns of an underlying wire as in a usual
cross-laid rope, which is therefore liable to local crushing and cross-cutting, two essential points of wear that have been completely eliminated in equal laid ropes.  They can be made in ordinary lay or Lang's lay.
Extra flexible.  Term used in describing either 8 x 19 or 6 x 37 constructions of wire rope.
Filler.  An even number of wires is laid around an inner layer of half that number, each valley being filled with a smaller wire.  Each outer wire then beds in the valley formed by one main and one of the filler wires.
Flat.  Wire rope made of parallel alternating right-lay and left-lay ropes sewn together by relatively soft wires.
Flattened strand.  A rope formed of strands which have a wire of triangular section in the core of each strand; this gives a polygonal outline to the finished rope enabling it to stand up to hard wear.
Flexible.  A term used in describing constructions of wire rope of 6 x 9 and larger numbers of individual wires.
Half-lock.  The outer layers are made up of shaped wires with grooves so formed as to permit the insertion of a fixed diameter cylindrical wire between two grooves during rope fabrication.  This, together with the lay, exerts a semi-locking action and prevents fractured wires within the layer from drifting out of lock.
Hard laid.  Rope formed from large wires.  Also known as coarse laid rope.
Keystone strand.  A type of rope in which the wires of the strands are combined in a keystone or wedge shape, so arranged that when the rope is in use the wear is evenly distributed over its outside surface.
Lang's lay.  Wire rope in which the wires in the strands and the strands in the rope are laid in the same direction.  Offers a better wearing surface and should last longer than an ordinary lay, but need expert handling; should only be used when both ends of the rope are anchored and the load runs in guides or on rails.
Locked coil.  Smooth surfaced rope composed of concentric layers of wires with the exterior layer being shaped wires.  Interior layers re of shaped or round wires around a center of round wires.  The outer layers are made up of wires so shaped as to form a full lock with similar connecting units.  It is fabricated with up to four locking layers.  This form of rope has a very high density, and compared with other round ropes, permits the diameter to be reduced by as much as 20 percent, with corresponding reduction in the


weight of winding equipment.  Splicing is more difficult as also is detection of internal faults after use.
Non-rotating flat strand.  Rope in which a number of individual ropes arranged in alternate right- and left-lay are stitched together with a special soft steel sewing wire.
Ordinary lay.  Wire rope in which the wires in the strands and the strands in the rope laid in opposite directions.
Plastic coated.  Ordinarily steel wire ropes with a coating of a nylon-type thermoplastic, which is extruded round the rope under heat and pressure, are claimed to last eight to ten times longer than uncoated wire ropes, but are of course more costly.  The coating, which is transparent, seals the lubricant in the rope.
Preformed.   Wire rope in which the strands are permanently shaped, before fabrication into the rope, to the helical form they assume in the wire rope.
Seale construction.  Rope in which the strands are fabricated with an outer and inner layer of an equal number of wires, the outer being laid in the interstices formed by the inner.  It has a very solid cross section and the outer wires are larger to withstand abrasion.
Selvage.  A rope in which the wires are arranged parallel to each other and sewn with yarn, etc., to keep them together and keep out wet.
Tubular.  Formed of shaped interlocking wires without a core and therefore lighter than other types.  Can be in two- and three-layer form to give greater resilience.
WP -    Weatherproof.
XHHW -    Cross-linked polyethylene insulated, 90øC, dry location, 75øC wet location.
Yield Strength    The minimum stress at which a material will start to physically deform without further increase in load.
Yield Strength -    The minimum stress at which a material will start to physically deform without further increase in load.
Yield stress.                             The stress (load divided by original area of cross-section of a test piece) at which there is a sudden increase in elongation without any corresponding increase in load.  It is the point at which plastic yielding of the metal commences.  Also known as yield point.


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