FED-STD-228A
Method 1124.1
18 April 2014
THICKNESS, COTTON TAPE, DIAL MICROMETER
1. SCOPE
1.1 This method is intended for use in determining the thickness of cotton tape over the insulation of
insulated wire and cable.
2. SPECIMEN
2.1 The specimen should be a piece of the tape at least 2 feet in length taken from the inspection unit.
3. APPARATUS
3.1 The apparatus shall consist of a dial micrometer having a flat anvil not less than 0.25 inch in diameter
and a flat presser foot 0.25 ± 0.01 inch in diameter which exerts a total force of 3.0 ± 0.1 ounce on the
specimen, the force being applied by means of a weight. The surfaces of the anvil and presser foot shall
be parallel to within 0.0001 inch. The dial shall be graduated to read in mils or 0.0001 inch.
4. PROCEDURE
4.1 The specimen shall be free from mechanical damage. The specimen shall be placed on the anvil of
the dial micrometer and the presser foot lowered gently (not dropped) until it contacts the surface of the
specimen. The thickness of the tape shall be read from the dial and the value recorded. Three
measurements equally spaced along the length of the specimen shall be made.
4.2 If the wire or cable contains tapes applied in more than one layer, each layer shall be tested
separately.
5. RESULTS
5.1 Unless otherwise specified in the detail specification, three specimens from each inspection unit shall
be tested.
5.2 The average thickness of the tape of the inspection unit shall be the average of the results obtained
from the specimens tested.
5.3 The minimum thickness of the tape of the inspection unit shall be the smallest of all values averaged
in determining the average thickness, 5.2.
5.4 The average thickness and minimum thickness of the tape of the inspection unit shall be recorded to
the nearest mil or 0.0001 inch.
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