MIL-DTL-13777K
4.8.4.1 Mechanical tests. Samples of the completed cable prepared as specified on figure 1, connected in
series shall be subjected to the following tests: impact, bend and twist, respectively at a temperature of 68º to
95ºF. In each of these tests, a 110 or 220 volt, 60 Hz, ac potential with a prescribed load current of not less
than 0.5 ampere shall be indicated on a recording ammeter to permit the determination of failure caused either
by broken conductors or by short circuits between conductors. Failure due to either cause shall terminate the
test of a sample. The test procedures for impact, bend and twist respectively are approved tests and a similar
method shall be followed in performing all mechanical tests (see 3.8.2). The value obtained shall be derived
from test of three samples for the bend and twist and six samples for the impact. If any of the samples tested
do not comply with the requirements set forth, the lot shall be rejected.
4.8.4.1.1 High and low temperature. Specimens shall be temperature stabilized for a minimum of 48 hours at
160º±2ºF and while still at this temperature, tested for impact, bend and twist for a minimum of one half the
cycles specified in accordance with 3.8.2. The temperature shall gradually reduce to -65º±2ºF and the
specimens permitted to remain at this temperature for a minimum of 48 hours. While still exposed at this
temperature, the impact, bend, and twist tests shall be conducted for a minimum of one half the cycles
specified in accordance with 3.8.2. At the conclusion of the test, the specimens shall be returned to room
temperature. If failure occurs in any of the specimens an additional set of specimens shall be tested. Further
evidence of failure will result in the withholding of approval (see Appendix A).
4.8.4.1.2 Cold bend. Two specimens of cable shall be subjected to cold bend testing at a temperature of -
65º±2ºF. The specimens shall be placed in the cold chamber in a nonflexed position and maintained at the
required temperature for a minimum of 48 hours. Without removal from the cold chamber each specimen shall
be bent around a mandrel as specified in table X at a rate of five turns per minute for one complete turn. Upon
removal from the cold chamber the specimens shall be examined for conformance 3.8.1. The insulated
conductors shall be removed from the jacket and tested by application of the test voltages specified in the
applicable specification sheet.
4.8.4.1.3 Torque test. Two specimens of cable shall be subjected to cold bend testing at a temperature of -
65º±2ºF. Prior to cold bend testing the specimens shall be oven-aging at a temperature of 160º±2 ºF for 2 days.
After oven aging, the specimens shall be placed in the cold chamber in a nonflexed position and maintained at
the required temperature for a minimum of 48 hours prior to testing. Without removal from the cold chamber,
each specimen shall be bent around a mandrel as specified in table X at a rate of five turns per minute for one
complete turn. The torque required to accomplish the turn shall be in accordance with 3.8.1.1. At the
conclusion of the test the temperature shall be gradually returned to room temperature and examined for
conformance with 3.8.1. The insulated conductors shall be removed from the jacket and tested by application
of the test voltage specified in the applicable specification sheet for one minute while submerged in water.
TABLE X. Cold bend mandrel sizes. 1/ 2/
Cable outside diameter inch (mm)
Mandrel size maximum inch (mm)
From
To
Unshielded
Shielded
.000 (.00)
.300 (7.62)
1.0 (25.40) X OD
3.0 (76.20) X OD
.301 (7.65)
.350 (8.89)
2.0 (50.80) X OD
3.0 (76.20) X OD
.351 (8.92)
.450 (11.43)
2.5 (63.50) X OD
3.0 (76.20) X OD
.451 (11.46)
.550 (13.97)
3.0 (76.20) X OD
3.0 (76.20)X OD
.551 (14.00)
.750 (19.05)
4.0 (101.60) X OD
4.0 (101.60)X OD
.751 (19.08)
.950 (24.13)
5.0 (127.00) X OD
5.0 (127.00)X OD
.951 (24.16)
1.500 (38.10)
6.0 (152.40) X OD
6.0 (152.40)X OD
1.501 (38.13)
2.000 (50.80)
8.0 (203.20) X OD
8.0 (203.20) X OD
2.001 (50.83)
and over
10.0 (254.00) X OD 10.0 (254.00) X OD
1/ Dimensions are in inches.
2/ Metric equivalents are given
for information only.
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