MIL-DTL-13777K
4.8.2.3.2 Polyamide jackets over shield. A sufficient length of specimen shall be used to insure at least six
close turns when bent on a metal mandrel, six times the outside diameter of the specimen. Each turn shall be
in contact with the next. The ends of the specimen shall be taped together in such a manner that the turns are
held in place on the mandrel. The mandrel and specimen shall be suspended in a gravity convection type oven
at a temperature of 300ºF±5ºF for a period of 15 minutes. The mandrel and specimen shall be removed from
the oven and cooled in a silica gel desiccator or equivalent until the specimen is at room temperature (1 hour
minimum). Remove from the desiccator and unwrap the coils. The specimen shall be visually inspected for
tears and cracks. Wrinkles shall not be a cause for rejection.
Note: During this test, the insulation will soften and flow. This shall not be cause for rejection.
4.8.2.4 Colored stripe tests.
4.8.2.4.1 Durability test. A short specimen of finished wire or sheath shall be firmly clamped in a horizontal
position with its upper longitudinal surface area freely exposed. A small steel mandrel 0.025 inch (.06 mm)
diameter +/-0.001 inch (.03 mm) shall be repeatedly rubbed over the insulation surface at the stripe so that the
longitudinal axis of the mandrel and specimen will be at right angles to each other. A weight shall be affixed to
the jog holding the rubbing mandrel so that the combined jig and weight exerts a 500-gram thrust normal to the
insulation surface. A motor-driven reciprocating cam mechanism and counter shall be used to permit an
accurately measured number of abrasion strokes. The length of the stroke in one direction shall be 0.375 inch
(9.53 mm) and the frequency of the stroke shall be 120 strokes per minute (each stroke consisting of a 180
degree-rotation of the eccentric drive mechanism). The direction of motion shall be along the axis of the wire or
cable jacket and perpendicular to the axis of the mandrel. This procedure shall be repeated on one additional
specimen selected for at least 50 feet apart. Specimens shall be examined for conformance with 3.5.5.4 and
4.8.2.4.2 Surface resistance test. The surface resistance of the black stripe insulated conductors shall
conform to 3.5.5.1.1 when tested in accordance with method 6041 of FED-STD-228. All specimens, after
having been provided with the required electrodes but prior to testing, shall be cleaned by the procedure
described in the test method. In positioning the specimens in the test chamber, the specimens shall be so
placed that their ends are a minimum of one inch from any wall of the chamber.
4.8.2.5 Electrical tests.
4.8.2.5.1 Electrode spark test. Method 6211 of FED-STD-228 shall be used in conducting the spark test
except that the speed of the specimen through the electrode shall be adjusted so that contact between the
electrode and any point on the insulation of the specimen will be maintained for at least 0.25 second. The used
of voltmeter-equipped spark testers shall be optional (see 3.5.3.1).
4.8.2.5.1.1 Dielectric test (insulated conductors). Each reel of insulated conductors shall be tested by the
cable manufacturer in accordance with method 6111 of FED-STD-228 except that the soak time shall be
reduced to 4 hours without stirring the bath and with both ends of the conductor tied together and connected to
the high voltage. The test shall be conducted after extrusion of the polyamide. There shall be no evidence of
breakdown when tested at the voltages of 3.5.3.2.
4.8.2.5.1.2 Impulse dielectric test. The impulse dielectric test shall be performed in accordance with method
3002 of MIL-STD-2223 to meet the requirements of 3.5.3.2 with exception that if any dielectric failures occur
they must be cut out or suitably identified for subsequent removal along with a minimum of 6 inches
(152.40 mm) of conductor on each side of the fault.
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