FED-STD-228A
Method 1018.1
18 April 2014
THICKNESS, INSULATION; OPTICAL
1. SCOPE
1.1 This method is intended for use in determining the thickness of the insulation of insulated wire and
cable. It is more accurate than methods 1011 and 1013. This method is recommended for use where a
high degree of accuracy and precision is desired. In case a dispute arises as to method for determining
the thickness of insulation, this method should be used wherever applicable.
2. SPECIMEN
2.1 The specimen should be a short length of the inspection unit with full cross-section of the insulation
cut perpendicular to the axis of the wire or cable.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents should be as follows:
3.1.1 Microscope equipped with devices capable of making measurements accurate to at least 0.0002
inch.
3.1.2 A suitable instrument is a standard microscope equipped with a 6- or 8-power eyepiece, an
objective of 48-millimeter focal length, a mechanical stage, and a ruled glass disc or slide.
3.1.3 Wiping cloth.
3.1.4 Alcohol or other suitable solvent.
4. PROCEDURE
4.1 Average thickness.
4.1.1 the specimen shall be free from mechanical damage and shall be cut perpendicular to the axis of
the wire or cable so as to expose the full cross-sectional area of insulation. Any saturants or other
extraneous materials shall be removed from the specimen by means of the cloth and solvent.
4.1.2 When the apparatus described in 3.1.2 is used, the ruled glass disc or slide shall be placed on the
cut surface of the cross section of the specimen with the ruled surface in contact with the insulation. The
thickness of the insulation, if not more than ¼ inch, will be in the field of view and shall be read directly
from the rulings. If the thickness is such that it does not all lie in the field of view and cannot be read
directly, the specimen shall be moved by means of the mechanical stage until the inner edge of the
insulation is tangent to a cross hair in the ocular. The specimen shall be moved by means of the stage
until the outer edge of the insulation is tangent to the cross hair. The rulings on the disc or slide passed
over during the movement shall be counted and the value recorded.
9
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business