MIL-DTL-25038J
4.5.3 Sample. A sample shall consist of one or more sample units chosen at random from the
inspection lot.
4.5.4 Sample unit. A sample unit shall consist of a piece of finished wire chosen at random from the
inspection lot and of sufficient length to permit all applicable inspections and tests. A sample unit for
quality conformance tests under this specification shall be 75 continuous linear feet of finished wire. Not
more than one sample unit shall be taken from a single unit of product.
4.5.5 Specimen. A specimen is a portion of finished wire taken from the sample unit for the
performance of a particular inspection or test.
4.6 Methods of inspection and test.
4.6.1 Visual and mechanical examination. Wire shall be examined to verify that the materials,
design, construction, physical dimensions, splices, marking, and workmanship are in accordance with the
requirements specified herein.
4.6.2 Concentricity. The concentricity of the insulation around a conductor shall be determined by
first locating and recording the minimum wall thickness of a cross section of the insulation. From this
point, on the outer rim of the insulation, at which the minimum wall thickness was measured, three more
reference points 90° apart on the outside rim of the insulation shall be established. At each of these three
reference points, the nearest strand of the conductor shall be selected and the insulation wall thickness
between that strand and the outer rim of the insulation shall be measured and recorded. The average of
the four measures shall be considered to be average wall thickness. Concentricity shall be expressed as
the ratio of minimum-to-average wall thickness times one hundred. A wall thickness measurement shall
be interpreted to be the minimum distance between the outer rim of the insulation and the rim of the
outermost strand of the stranded conductor. All wall thickness measurements shall be determined under
suitable magnification.
4.6.3 Conductor tensile strength and elongation. After stranding, individual strands shall be tested in
accordance with method 3211 of FED-STD-228.
4.6.4 High temperature endurance. A suitable length of finished wire from each qualification (or
conformance) sample shall be placed in an air oven that shall be maintained at 650±5 °F. The wire shall
be placed in the oven in a manner such that two layers of wire are not touching. Either a circulating or a
non-circulating oven may be used. The ends of the specimen that are outside the oven shall be
connected to an electric source that may be either ac or dc. The current through the conductor shall be
adjusted to stabilize at the value given in table V for the applicable wire size. When the stabilized
conductor current is reached, voltage and current measurements shall be recorded. The current loaded
wire shall remain in the air oven at an oven temperature of 650±5 °F for a period of 100 hours (48 hours
for conformance test). The current through the conductor shall be checked daily and maintained at the
required test value. At the end of the 100-hour period (48 hour period for conformance test) and while still
at the stabilized temperature and conductor current, a final voltage and current measurement shall be
made. Change in resistance during the conditioning period shall be calculated from the voltage and
current measurements. The wire shall then be cooled to room temperature and examined for visual
defects without magnification. Change in color of the finished wire or printed identification shall not be
considered a defect. The ends of the wire sample that were outside the oven during conditioning shall be
discarded. From the wire that was inside the oven during conditioning, the following 3-foot specimens
shall be cut for further testing:
11
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business