U \(see 6.4\).

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MIL‐DTL‐3241F

3.2 Steel reel heads. The heads of the reels, except DR-8( ), shall be made of steel which, after heat

treatment, shall have the properties specified below (see 4.10):

Tensile strength

-135,000 p.s.i. minimum (see 4.10.1).

Yield strength (0.1%)

-120,000 p.s.i. minimum (see 4.10.1).

Elongation at rupture

-7 percent minimum (see 4.10.1).

Hardness

-Rockwell C31 to C41 (Brinnell 294 to 381) (see

4.10.2).

3.3 Welding. Whenever practicable, welded joints shall conform to MIL-STD-22 and shall be such that

grinding on the finished weld will be unnecessary. Spot, seam and projection welds shall conform to MIL-

W-12332. Butt welds shall conform to the requirements specified in the cable reel drawings in paragraph

3.1. When spot or other intermittent welds are used to hold a part, the number of welds shall be at least

two.

3.3.1 Cleaning prior to welding. Surfaces to be welded shall be cleaned In accordance with good

commercial practice and shall be free from rust, scale, paint, grease, and other foreign material.

3.3.2 Process. Preheating shall be employed where distortion is likely to result from welding. Welds

shall have a thorough penetration and good fusion and shall be free from scabs, blisters, abnormal pock

marks, crack, voids, slag inclusions, and other harmful defects. Where undesirable internal stresses are

likely to result from welding, welded items shall be stress-relieved.

3.3.3 Cleaning after welding. Welded assembles shall be cleaned to remove rust, scale, oxidation

products, and excess flux by sandblasting, wire brushing, or other suitable means. Prior to painting steel

parts that have been arc or acetylene welded, parts shall be subjected to vat passivation or a phosphoric

acid etch in accordance with MIL-C-10578. Acid used for cleaning shall be completely neutralized and

removed. Sandblast cleaned items shall be finished or a protective coating shall be applied within four

hours of its cleaning.

3.3.4 Weld inspection. Inspection of weld joints shall be made in accordance with, and meet the

requirements of MIL-STD-1907 (see 4.9).

3.4 Fit on axle. When tested as specified in 4.5, the fit on the axle shall be such that the axle can be

completely inserted and withdrawn without binding.

3.5 Alignment. On completed reels no point on the circumference of the head shall be more than one-

fourth of an inch from the perpendicular to the axle, when tested as specified in 4.6.1. Measurements

shall be taken and recorded at four points 90 degrees apart on each head.

3.5.1 Plate alignment on reel RC-453( )/G. On completed reel RC-453( )/G, no point on the

circumference of the plates shall be more than one-fourth of an inch from the perpendicular to the drum

when tested as specified in 4.6.2. At no time shall the space within the connector compartment be less

than 3 inches.

3.6 Vibration. The reels shall show no evidence of permanent degradation including no loosening of

parts when tested as specified in 4.7.

3.7 Drop. The reels shall show no evidence of permanent degradation other than deformation, no

evidence of loosening of parts and shall exhibit a maximum deformation of no more than one inch when

tested as specified in 4.8. Alignment measurements shall be taken before and after each drop to the

point of impact. Maximum deformation is the difference between these measurements.

3.8 Moisture resistance. Upon completion of test specified in 4.11, there shall be no evidence of

corrosion or any other form of deterioration.