MIL-DTL-62474F
3.2 Materials. Materials used shall be in accordance with the manufacturer's materials
specifications for aramid fabrics. The materials shall be capable of meeting all the operational
and environmental requirements specified herein (see 4.4).
3.2.1 Aramid fabrics.
3.2.1.1 Class A laminates. The aramid fabric reinforcement used in class A laminates
shall be woven from an aramid yarn of nominal 1500 denier, minimal 975 filaments, 1 percent
finish. All yarn shall be of the same production lot as defined in ASTM D123. The fabric
construction shall be 42 +2 ends per 25.4 mm by 42 +2 picks per 25.4 mm in a 7 x 7 basket
weave as determined by ASTM D3775. Yarns shall have zero twist (see 4.4).
3.2.1.2 Class B laminates. The aramid fabric reinforcement used in class B laminates
shall be woven from an aramid yarn of nominal 3000 denier, minimal 1300 filaments, 1 percent
finish. All yarn shall be of the same production lot as defined in ASTM D123. The fabric
construction shall be 21 +1 ends per 25.4 mm by 21 +1 picks per 25.4 mm in a 4 x 4 or 2 x 2
basket weave as determined by ASTM D3775. Yarns shall have zero twist (see 4.4).
3.2.1.3 Class A and class B. The aramid fabrics described in 3.2.1.1 and 3.2.1.2, shall
have a moisture-free weight of 16.25 +0.75 ounces per square yard (oz/yd2) [551 +25 grams per
square meter (g/m2)] as determined by ASTM D3776 (option C) after drying in accordance with
Section 9 of ASTM D629. The sample shall be dried until the loss in mass is minimal or when a
constant mass has been reached. This constant mass shall be considered the moisture-free
weight. If sizing is used in the weaving process, it shall be a water soluble polyvinyl alcohol. If
sizing is used, the fabric shall be cleaned (scoured) to a maximum content of 0.5 weight percent
of the moisture-free fabric weight. The maximum moisture content of the aramid fabric after
weaving or weaving and scoring shall be five (5) percent by weight as determined by ASTM
D629, Section 9. Fabric quality shall conform to paragraph 3.3 of AMS 3902. Selvages shall be
woven or three-end leno. Tension in warp and fill shall be adequate to assure uniform fabric
construction after resin coating/impregnation (see 4.4).
3.2.1.4 Class C and class D laminates. The aramid fabric reinforcement used in class C
and D laminates shall be woven from an aramid yarn of nominal 3000 denier, minimal 1300
filaments, 1 percent finish. All yarn shall be of the same production lot as defined in ASTM
D123. The fabric construction shall be 17 +1 ends per 25.4 mm by 17 +1 picks per 25.4 mm in a
plain weave as determined by ASTM D3775. Yarns shall have zero twist (see 4.4).
3.2.1.5 Class C and class D. The aramid fabric described in 3.2.1.4, shall have a
moisture-free weight of 13.5 +/- 1.0 ounces per square yard (oz/yd2) [450 +/- 30 grams per
square meter (g/m2)] as determined by ASTM D3776 (option C) after drying in accordance with
Section 9 of ASTM D629. The sample shall be dried until the loss in mass is minimal or when a
constant mass has been reached. This constant mass shall be considered the moisture-free
weight. If sizing is used in the weaving process, it shall be a water soluble polyvinyl alcohol. If
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