FED-STD-228A
Method 1014.1
18 April 2014
THICKNESS, INSULATION, MINIMUM; PIN-GAGE DIAL MICROMETER
1. SCOPE
1.1 This method is intended for use in determining the minimum thickness of the insulation of insulated
wire and cable. It is recommended for use when the thickness of the insulation is less than 3/64 inch. It is
more rapid than method 1018 but is less accurate. It is not applicable to the insulation from a stranded
conductor or when the diameter of the conductor is less than 0.042 inch.
2. SPECIMEN
2.1 The specimen should be a piece of the inspection unit approximately 3 inches in length from which
any covering over the insulation, and the separator and conductor have been removed without splitting
the insulation. The inner wall of the specimen should not be torn or damaged in removing the separator
or conductor.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents should be as follows:
3.1.1 A pin-gage dial micrometer with a fixed pin 0.042 ± 0.0001 inch in diameter and ¾ ± 1/16 inch in
length as the anvil and a flat presser foot 0.042 ± 0.0001 inch wide and 0.312 ± 0.002 inch long, which
exert a total force of 25 ± 2 grams on the specimen, the force being applied by means of a weight. The
micrometer should be graduated to read in mils of 0.0001 inch.
3.1.2 Wiping cloth.
3.1.3 Alcohol or other suitable solvent.
4. PROCEDURE
4.1 The inspection unit shall be examined for thin places in the insulation. The specimen shall be taken
from the inspection unit so as to include the point where the insulation is considered the thinnest and shall
be free from mechanical damage. Any saturants or extraneous materials shall be removed from the
insulation by means of the cloth and solvent. The specimen shall be slipped over the pin of the
micrometer and the presser foot lowered gently (not dropped) until it contacts the outer surface of the
insulation. The thickness of the insulation shall be read from the dial immediately after the presser foot
has come to rest on the specimen. The specimen shall be rotated and at least 5 measurements made
around the circumference of the specimen in order to find the minimum thickness which shall be
recorded. The presser foot of the gage shall not be in contact with the specimen while it is being rotated.
4.2 If no thinnest point is located in the insulation of the inspection unit, and useless otherwise specified
in the detail specification, three specimens from the inspection unit shall be tested.
5. RESULTS
5.1 If a thinnest point is found in the insulation of the inspection unit, 4.1, the minimum thickness of the
insulation of the inspection unit should be the thickness of the insulation obtained at that point.
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