UL 1581 Cold Bend Test

COLD BEND
580 Test

580.1 The specifications for this test are located in Cold Bend, in the Standard for Wire and Cable Test Methods, UL 2556. Note – When a mandrel specified in the product standard is not available, it shall be permitted to use a mandrel with a smaller diameter. However, in the event of non-compliant results, the wire or cable shall be re-tested using the mandrel size specified in the product standard.

7.5 Cold bend

7.5.1 Scope

This test establishes the method for determining the resistance to cracking of wire or cable components
during bending at low temperature.

7.5.2 Apparatus

The apparatus shall consist of
a) a low-temperature chamber capable of maintaining the specified temperature within ±1 °C;
b) a temperature-measuring device with an accuracy of ±1 °C;
c) a micrometer or micrometer caliper with a resolution and accuracy of 0.01 mm (0.001 in);
d) cylindrical mandrels of diameters specified in the product standard; and
e) thermally insulated gloves.

7.5.3 Preparation of specimens

The specimen shall be cut to a length sufficient to perform the test and shall be straightened.

7.5.4 Procedure

7.5.4.1 The specimen and the mandrel shall be placed in the cold chamber at the temperature and for
the duration specified in the product standard. While still in the chamber, the specimen shall be bent
around the mandrel. Bending shall commence as quickly as possible and at a rate such that the time
taken to complete the specified number of turns shall be within 30 s. Flat cable shall be wound on its flat
side.

7.5.4.2 Where there is insufficient space in the cold chamber for the mandrel, or for bending the
specimen, bending of the specimen shall be allowed to take place outside of the cold chamber. Bending
of the specimen shall commence as quickly as possible. In the instance where the mandrel is too large to
be placed in the chamber, it shall be maintained at ROOM TEMPERATURE. In any case, bending shall
be completed within 30 s from the time the chamber is opened.

7.5.4.3 If the tension on the specimen is not specified, it shall be just sufficient to cause the specimen to
conform to the periphery of the mandrel. Unless rotation of the mandrel is performed remotely, the
specimen and mandrel shall be handled using thermally insulated gloves.

7.5.4.4 The specimen, whether on or off of the mandrel, shall be allowed to return to ROOM
TEMPERATURE and then straightened. The inside and outside surfaces of the components shall be
examined for cracking.

7.5.5 Results and calculations
The presence of cracks, if any, shall be noted.

7.5.6 Report

The report shall include, as a minimum, the following:
a) test temperature; and
b) indication of cracking, if any.