This test determines the elongation of insulation of a wire in a circumferential direction. This test was developed to measure the resistance of polytetrafluoroethylene (PTFE) insulation to rupture when under a radial stress. Using a power driven apparatus built by Lectromec technicians, a cone shall be driven through the insulation. At the end of the test, the average percent circumferential elongation shall be calculated.
General procedure: A power driven apparatus capable of driving a test cone at 20 ± 2 inches/minute shall be used. A 1 to 1.5 inch strip of insulation shall be removed from the conductor which will then be cut into 5 cylindrical test specimens 0.125 ± .02 inches in length. Slide a specimen onto the cone until it just touches the edges of the cone attached to the apparatus. Align the cone top and the appropriate sized hold of the specimen holding block for the wire size being tested. Move the cone through the stationary specimen at a uniform speed of 20 ± 2 inches/minute until the specimen ruptures. The percent circumferential elongation shall be calculated using mathematical formulas provided in the specification document.
The test procedure listed here is taken from MIL-STD-2223 and has been modified to reflect the purpose and general procedure of this test. The particular test procedures may vary depending on the particular test standard.