FED-STD-228A
Method 2161.1
18 APRIL 2014
SPRINGINESS, ARMOR WIRE
1. SCOPE
1.1 This method is intended for use in determining the ability of a braided metal armor to remain tight on
the sheath or core material during and after fabrication of the cable.
2. SPECIMEN
2.1 The specimen should be a 2-foot length of the wire taken from the armor of the inspection unit. An
equivalent length taken from the wire before braiding may be used when specified in the detail
specification.
3. APPARATUS
3.1 The apparatus shall be as follows:
3.1.1 Steel mandrel 0.25 ± 0.01 inch in diameter.
3.1.2 Weight as required in 4.1.
3.1.3 Any suitable machine for holding and turning the mandrel about its own axis. A satisfactory device
is a power-driven lathe equipped with chuck.
3.1.4 Binding wire or cord.
3.1.5 Micrometer caliper graduated to read to mils or 0.0001 inch, and having flat surfaces on both anvil
and end of spindle, each approximately 0.25 inch in diameter. The surfaces of the anvil and spindle shall
be parallel to within 0.0001 inch.
4. PROCEDURE
4.1 Unless otherwise specified in the detail specification, a weight of 100 grams shall be used.
4.2 The mandrel shall be centered in the chuck of the lathe and supported at the free end on a center.
The specimen shall be bent around the mandrel and fastened by means of a binding core or wire. The
required weight shall be applied to the free end of the specimen and the chuck turned at approximately 20
revolutions per minute to wind the specimen on the mandrel. Adjacent turns of the wire shall be kept as
close to each other as practicable.
4.3 After the specimen has been wound around the mandrel, the diameter over the armor wire coil shall
be measured and the value recorded as D1. The anvil and spindle of the micrometer caliper shall be just
brought into contact with the surface of the armor wire in such a manner that it is not distorted. The
criterion of contact is the initial development of frictional resistance to movement of the armor wire
between the micrometer surfaces. The weight shall be detached and the armor wire coil removed from
the mandrel. The diameter over the coil shall be measured as described above and the value recorded
as D2. Five measurements near the middle of the coil shall be made and the average recorded as D1 and
D2 respectively. The diameter over the coil before and after removal from the mandrel shall be
determined as nearly as practicable at the same point.
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