MIL-DTL-25038J
4.6.14.1 Apparatus. The marking durability tester shall hold a short specimen of finished wire firmly
clamped in a horizontal position with the upper longitudinal surface of the specimen fully exposed. The
tester shall be capable of rubbing a small cylindrical steel mandrel (usually a needle), .025 inch (.64 mm)
in diameter, repeatedly over the upper surface of the wire, in such position that the longitudinal axes of
the mandrel and the specimen are at right angles to each other with cylindrical surfaces in contact. A
weight affixed to a jig above the mandrel shall control the force exerted normal to the surface of the
insulation. A motor-driven reciprocating cam mechanism and counter shall be used to deliver an accurate
number of abrading strokes in a direction parallel to the axis of the specimen. The length of the stroke
shall be .375 inch (9.52 mm) and the frequency shall be 120 strokes (60 stroking cycles) per minute.
4.6.14.2 Test procedure. A specimen of finished wire shall be mounted in the specimen clamp and
the jig shall be adjusted to deliver a weight of 150g through the abrading mandrel to the markings on the
insulation. The specimen shall be subjected to 500 strokes (250 cycles) of the mandrel and shall then be
examined using the naked eye. If there is a continuous line of erasure or obliteration through the stripe,
band, or printed identification marking, exposing the primary insulation, the specimen shall be considered
as having failed. Three specimens shall be tested for each sample unit and failure of any specimen shall
constitute failure of the sample unit.
4.6.15 Finished wire weight. The weight of the finished wire shall be measured for compliance with
the weight specified in the applicable specification sheet. The weight of each lot of finished wire shall be
determined by procedure I (see 4.6.15.1). Lots failing to meet the wire weight requirement in accordance
with procedure I shall be subjected to procedure II (see 4.6.15.2). All reels or spools failing to meet the
requirements of the applicable specification sheet shall be rejected.
4.6.15.1 Procedure I. The length and weight of a specimen at least 10 feet long shall be accurately
measured with the resultant measurements transposed to pounds per 1,000 feet.
4.6.15.2 Procedure II. The net weight of the finished wire on each reel or spool shall be obtained by
subtracting the tare weight of the reel or spool from the gross weight of the reel or spool containing the
finished wire. The net weight of wire on each reel or spool shall be divided by the accurately determined
length of finished wire on that reel or spool and the result converted to pounds per 1,000 feet. When
wood or moisture absorbent materials are used for reel or spool construction, weight determinations shall
be made under essentially the same conditions of relative humidity.
4.6.16 Circular Mil Area (CMA). Before the application of any insulation, the stranded conductor
shall be tested in accordance with ASTM B263. Appropriate K values and the minimum CMA values are
listed in table II.
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