MIL‐DTL‐3241F
4.7.1 Direction of vibration. The reels shall be vibrated successively, over the specified ranges of
applied frequencies, in three mutually perpendicular directions parallel to the edges of the reels.
4.7.2 Rate of change of vibration frequency. The frequency of the applied vibration shall be varied
uniformly at a rate of approximately one Hz per minute.
4.7.3 Amplitude and frequency of applied vibration. The amplitude (one-half of the total excursion) of
the vibration table and the frequency range shall be in accordance with the following:
Amplitude of vibration (in)
Frequency of vibration (hz)
10 to 33
Horizontal
Vertical
0.020
0.030
4 7.4 Duration of test. The reels shall be vibrated for at least six hours, two hours in each of the three
directions specified in 4.7.1.
4.7.5 At the conclusion of the tests, the reels shall be examined for compliance with 3.6.
4.8 Drop test. The drop test shall be performed on the reels specified in 4.8.1 prior to finishing. The
reel loaded with wire or cable shall be conditioned in a temperature chamber at -40 degree F for 24 hours
prior to the drop test. The drop test shall be conducted immediately as soon as the reel is removed from
the temperature chamber. If all the specified drops cannot be completed within 10 minutes after removal,
immediately return the reel to the -40 degree F temperature chamber for 1 hour before proceeding to the
next 10 minute test period during which the reel may be dropped. After each 10 minute test period,
immediately return the reel to the cold temperature chamber before proceeding to the next 10 minute test
period until all the specified drops have been completed.
4.8.1 Each type of reel shall be loaded with a weight of wire or cable comparable to its normal use with
total weight as follows:
DR-5( )
125 pounds
DR-7( )
133 pounds
DR-8( )
15 pounds
RC-453( )/G
150 pounds
RL-159( )/U
50 pounds
4.8.2 The reel shall be lifted off the floor by use of a hoist, equipped with a quick release device. When
the bottom of the reel is 3-1/2 feet above the 2 inch fir platform backed by a concrete floor, It shall be
released so as to drop squarely on the perifery of both heads.
4.8.3 The reel shall then be lifted as above, held until motionless, and dropped squarely on one side.
Then repeat on other side.
4.8.4 The reel shall be lifted at a single point at the edge of one head, held until motionless, and then
dropped so that the reel will land on the opposite head at an angle to the perifery of one head. Repeat
the same procedure on the other head.
4.8.5 At the conclusion of the tests, the reel shall be examined for compliance with 3.7.
4.9 Welding inspection. Welding shall be testing for nonvisual defects by magnetic particle method
specified in ASTM E1444 for compliance with 3.3.4.
4.10 Steel reel heads.
4.10.1 The yield strength, tensile strength, and elongation at rupture of the steel reel heads shall be
tested in accordance with ASTM E8/E8M for compliance with 3.2.
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