FED-STD-228A
Method 1013.1
18 April 2014
THICKNESS, INSULATION; DIAL MICROMETER
1. SCOPE
1.1 This method is intended for use in determining the thickness of the insulation of insulated wire and
cable. It is not recommended for use when the nominal thickness of the insulation is less than 3/64 inch.
It is faster than method 1011.
2. SPECIMEN.
2.1 The specimen should be a piece of the inspection unit at least 2 feet in length from which any
covering over the insulation has been removed.
3. APPARATUS AND REAGANTS
3.1 The apparatus and reagents should be as follows:
3.1.1 Dial micrometer with a flat anvil and a flat pressure foot 0.078 ± 0.003 inch wide and 0.375 ± 0.015
inch long which exerts a total force of 10 ± 2.0 grams on the specimen, the force being applied by means
of a weight. The surfaces of the anvil and pressure foot should be parallel to within 0.0001 inch. The dial
should be graduated to read in mile or 0.0001 inch.
3.1.2 Wiping cloth.
3.1.3 Alcohol or other suitable solvent.
4. PROCEDURE
4.1 Average thickness.
4.1.1 The specimen shall be free from mechanical damage. Any saturants or other extraneous materials
shall be removed from the specimen by means of the cloth and solvent. The specimen shall be placed on
the anvil of the micrometer and the presser foot lowered gently (not dropped) until it contacts the surface
of the insulation. The diameter over the insulation shall be read from the dial and the value recorded as
D1.
4.1.2 The insulation shall then be removed from the conductor and the diameter over the conductor or
the separator (if one is used) measured as described above and the value recorded as D2.
4.1.3 Three sets of measurements equally spaced along the length of the specimen shall be made.
Each set of measurements shall consist of the maximum and minimum diameters at the place measured.
The diameter over the insulation and over the conductor or separator (if one is used) shall be determined
as nearly as practicable at the same point.
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