ASTM D374-99(2004)

Standard Test Methods for Thickness of Solid Electrical Insulation (Withdrawn 2013)

SIGNIFICANCE AND USE
Some electrical properties, such as dielectric strength, vary with the thickness of the material. Determination of certain properties, such as relative permittivity (dielectric constant) and volume resistivity, usually require a knowledge of the thickness. Design and construction of electrical machinery require that the thickness of insulation be known.
SCOPE
1.1 These test methods cover the determination of the thickness of several types of solid electrical insulating materials employing recommended techniques. Use these test methods except as otherwise required by a material specification.
1.2 The values stated in inch-pound units are the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
WITHDRAWN RATIONALE
These test methods cover the determination of the thickness of several types of solid electrical insulating materials employing recommended techniques. Use these test methods except as otherwise required by a material specification.
Formerly under the jurisdiction of Committee D09 on Electrical and Electronic Insulating Materials, this practice was withdrawn in January 2013 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.

General Information

• Status: Withdrawn
• Publication Date: 09-Mar-1999
• Withdrawal Date: 31-Dec-2012
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.12 - Electrical Tests

Relations

• Replaces: ASTM D374-99 - Standard Test Methods for Thickness of Solid Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM F2097-20 - Standard Guide for Design and Evaluation of Primary Flexible Packaging for Medical Products
• Effective Date: 10-Mar-1999
• Referred By: ASTM D876-21 - Standard Test Methods for Nonrigid Vinyl Chloride Polymer Tubing Used for Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM D202-23 - Standard Test Methods for Sampling and Testing Untreated Paper Used for Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM F119-82(2022) - Standard Test Method for Rate of Grease Penetration of Flexible Barrier Materials (Rapid Method)
• Effective Date: 10-Mar-1999
• Referred By: ASTM D1830-17 - Standard Test Method for Thermal Endurance of Flexible Sheet Materials Used for Electrical Insulation by the Curved Electrode Method
• Effective Date: 10-Mar-1999
• Referred By: ASTM D1710-15(2021) - Standard Specification for Extruded Polytetrafluoroethylene (PTFE) Rod, Heavy Walled Tubing and Basic Shapes
• Effective Date: 10-Mar-1999
• Referred By: ASTM D4733-17 - Standard Test Methods for Solventless Electrical Insulating Varnishes
• Effective Date: 10-Mar-1999
• Referred By: ASTM D5470-17 - Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials
• Effective Date: 10-Mar-1999
• Referred By: ASTM F1957-99(2017) - Standard Test Method for Composite Foam Hardness-Durometer Hardness
• Effective Date: 10-Mar-1999
• Referred By: ASTM D1082-17 - Standard Test Method for Dissipation Factor and Permittivity (Dielectric Constant) of Mica
• Effective Date: 10-Mar-1999
• Referred By: ASTM D1039-16(2022) - Standard Test Methods for Glass-Bonded Mica Used as Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM D350-21 - Standard Test Methods for Flexible Treated Sleeving Used for Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM D619-21 - Standard Test Methods for Vulcanized Fibre Used for Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM D3426-19 - Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials Using Impulse Waves
• Effective Date: 10-Mar-1999

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D374 −99(Reapproved 2004) An American National Standard
Standard Test Methods for
Thickness of Solid Electrical Insulation
This standard is issued under the fixed designation D374; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 4. Summary of Test Methods
4.1 This standard provides eight different test methods for
1.1 These test methods cover the determination of the
thickness of several types of solid electrical insulating materi- the measurement of thickness of solid electrical insulation
materials. The test methods (identified as Test Methods A
als employing recommended techniques. Use these test meth-
ods except as otherwise required by a material specification. through H) employ different micrometers that exert various
pressures for varying times upon specimens of different geom-
1.2 The values stated in inch-pound units are the standard.
etries.Table1andTable2displaybasicdifferencesofeachtest
1.3 This standard does not purport to address all of the
method and identify test methods applicable for use on various
safety concerns, if any, associated with its use. It is the
categories of materials.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 5. Significance and Use
bility of regulatory limitations prior to use.
5.1 Some electrical properties, such as dielectric strength,
vary with the thickness of the material. Determination of
2. Referenced Documents
certain properties, such as relative permittivity (dielectric
2.1 ASTM Standards: constant) and volume resistivity, usually require a knowledge
D1711 Terminology Relating to Electrical Insulation of the thickness. Design and construction of electrical machin-
D6054 Practice for Conditioning Electrical Insulating Mate- ery require that the thickness of insulation be known.
rials for Testing
6. Apparatus
E252 Test Method for Thickness of Foil, Thin Sheet, and
Film by Mass Measurement
6.1 Apparatus A— Machinist’s Micrometer Caliper with
Calibrated Ratchet or Friction Thimble:
3. Terminology 6.1.1 ApparatusAis a micrometer caliper without a locking
device but is equipped with either a calibrated ratchet or a
3.1 Refer to Terminology D1711 for definitions pertinent to
friction thimble. By use of a proper manipulative procedure
this standard.
andacalibratedspring(seeAnnexA1),thepressureexertedon
3.2 Definitions of Terms Specific to This Standard:
the specimen is controllable.
3.2.1 1 mil, n—a dimension equivalent to 0.0010 in.
6.1.2 Use an instrument constructed with a vernier capable
3.2.2 absolute uncertainty (of a measurement), n—the
of measurement to the nearest 0.1 mil.
smallest division that may be read directly on the instrument 6.1.3 Use an instrument with the diameter of the anvil and
used for measurement.
spindle surfaces (which contact the specimen) of 250 6 1 mil.
6.1.4 Use an instrument conforming to the requirements of
3.2.3 micrometer, n—an instrument for measuring any di-
7.1, 7.2, 7.5, 7.6.1, and 7.6.2.
mension with absolute uncertainty of 1 mil or smaller.
6.1.5 Periodically, test the micrometer for conformance to
the requirements of 6.1.4.
6.2 Apparatus B—Machinist’s Micrometer Without a
These test methods are under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and are the direct responsibility of Ratchet:
Subcommittee D09.12 on Electrical Tests.
6.2.1 Apparatus B is a micrometer caliper without a locking
Current edition approved Dec. 1, 2004. Published June 1999. Originally
device.
approved in 1933. Last previous edition approved in 1994 as D374 – 94. DOI:
6.2.2 Use an instrument constructed with a vernier capable
10.1520/D0374-99R04.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
of measurement to the nearest 0.1 mil.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Hereinafter referred to as a machinist’s micrometer.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D374−99 (2004)
TABLE 1 Test Methods Suitable for Specific Materials
6.3.1.7 An electronic instrument having a digital readout in
Material Test Method place of the dial indicator is permitted if that instrument meets
Plastic sheet and film A B C or D the other requirements of 6.3.
Paper (all thicknesses) E
6.3.2 The preferred design and construction of manually
Paper (over 2 mils thickness) F or G
operated dead-weight dial-type micrometers calls for a limit on
Rubber and other elastomers H
the force applied to the presser foot. The limit is related to the
compressive characteristics of the material being measured.
TABLE 2 Test Method Parameter Differences
6.3.2.1 The force applied to the presser foot spindle and the
Diameter of Pressure on
weight necessary to move the pointer upward from the zero
Test Presser Foot Specimen,
position shall be less than the force that will cause permanent
Apparatus
Method or Spindle, approximate,
deformation of the specimen. The force applied to the presser
mils PSI
footspindleandtheweightnecessarytojustpreventmovement
A Machinist micrometer with 250 not specified
calibrated ratchet or
of the pointer from a higher to a lower reading shall be more
thimble
than the minimum permissible force specified for a specimen.
B Machinist micrometer 250 unknown
without ratchet/thimble
6.4 Apparatus D—Motor-Operated Dead-Weight Dial
C Dead-weight dial type 125 to 500 0.5 to 130
Gage:
bench micrometer—Manual
D Dead-weight dial type 125 to 500 0.5 to 130
6.4.1 Except as additionally defined in this section, use an
bench micrometer—Motor
instrument that conforms to the requirements of 6.3.An
operated
E Dead-weight dial type 250 25 electronic instrument having a digital readout in place of the
bench micrometer—Motor
dial indicator is permitted if that instrument meets the other
operated
requirements of 6.3 and 6.4.
F Dead-weight dial type 250 25
bench micrometer—Manual
6.4.2 Use a motor operated instrument having a presser foot
G Machinist micrometer with 250 25
spindle that is lifted and lowered by a constant speed motor
calibrated ratchet or
through a mechanical linkage such that the rate of descent (for
thimble
H Dead-weight dial type 250 4
a specified range of distances between the presser foot surface
bench micrometer—Manual
and the anvil) and the dwell time on the specimen are within
thelimitsspecifiedforthematerialbeingmeasured.Designthe
mechanical linkage so that the only downward force upon the
6.2.3 Use an instrument with the diameter of the anvil and presserfootspindleisthatofgravityupontheweightedspindle
spindle surfaces (which contact the specimen) 250 6 1 mil.
assembly without any additional force exerted by the lifting/
6.2.4 Use an instrument conforming to the requirements of lowering mechanism.
7.1, 7.2, 7.5.1, 7.5.2, 7.5.3, 7.6.1, and 7.6.3.
6.4.2.1 The preferred design and construction of motor
6.2.5 Periodically, examine and test the micrometer for
operated dead-weight dial-type micrometers calls for a limit on
conformance to the requirements of 6.2.4.
the force applied to the presser foot. The limit is related to the
compressive characteristics of the material being measured.
6.3 Apparatus C— Manually-Operated, Dead-Weight, Dial
6.4.2.2 The force applied to the presser foot spindle and the
Type Thickness Gage:
weight necessary to move the pointer upward from the zero
6.3.1 Use a dead-weight dial-type gage in accordance with
position shall be less than the force that will cause permanent
the requirements of 7.1, 7.3, 7.4, 7.6.1, 7.6.4, that has:
deformation of the specimen. The force applied to the presser
6.3.1.1 Apresser foot that moves in an axis perpendicular to
footspindleandtheweightnecessarytojustpreventmovement
the anvil face,
of the pointer from a higher to a lower reading must be more
6.3.1.2 The surfaces of the presser foot and the anvil (which
than the minimum permissible force specified for a specimen.
contact the specimen) parallel to within 0.1 mil (see 7.3),
6.3.1.3 A vertical dial spindle,
7. Calibration (General Considerations for Care and Use
6.3.1.4 Adial indicator essentially friction-free and capable
of repeatable readings within 60.05 mil at zero setting, or on of Each of the Various Pieces of Apparatus for
Thickness Measurements)
a steel gage block,
6.3.1.5 A frame, housing the indicator, of such rigidity that
7.1 Good testing practices require clean anvil and presser
a load of 3 lbf applied to the dial housing, out of contact with
foot surfaces for any micrometer instrument. Prior to calibra-
the presser foot spindle (or any weight attached thereto) will
tion or thickness measurements, clean such surfaces by insert-
produce a deflection of the frame not greater than the smallest
ing a piece of smooth, clean bond paper between the anvil and
scale division on the indicator dial, and,
thepresserfootandslowlymovingthebondpaperbetweenthe
6.3.1.6 Adial diameter at least 2 in. and graduated continu-
surfaces. During measurements, check the zero setting fre-
ously to read directly to the nearest 0.1 mil. If necessary, equip
quently. Failure to repeat the zero setting may be evidence of
the dial with a revolution counter that displays the number of
dirt on the surfaces.
complete revolutions of the large hand.
NOTE 1—Avoid pulling any edge of the bond paper between the
surfaces to reduce the probability of depositing any lint particles on the
Herein referred to as a dial gage. surfaces.
D374−99 (2004)
7.2 The parallelism requirements for machinist’s microm- 7.4.2.2 A grooved surface forms straight parallel fringes at
eters demand that observed differences of readings on a pair of unequal intervals.
screw-thread-pitch wires or a pair of standard 250-mil nominal
7.4.2.3 A symmetrical concave or convex surface forms
diameter plug gages be not greater than 0.1 mil. Spring-wire
concentric circular fringes. Their number is a measure of
stockormusic-wireofknowndiameteraresuitablesubstitutes.
deviation from flatness.
The wire (or the plug gage) has a diameter dimension that is
7.4.2.4 An unsymmetrical concave or convex surface forms
known to be within 60.05 mil. Diameter dimensions may vary
a series of curved fringes that cut the periphery of the
by an amount approximately equal to the axial movement of
micrometer surface. The number of fringes cut by a straight
the spindle when the wire (or the plug gage) is rotated through
line connecting the terminals of any fringes is a measure of the
180°.
deviation from flatness.
7.2.1 Lacking a detailed procedure supplied by the instru-
7.5 Machinist’s Micrometer Requirements :
ment manufacturer, confirm the parallelism requirements of
7.5.1 The requirements for zero reading of machinist’s
machinist’s micrometers using the following procedure:
micrometers are met when ten closings of the spindle onto the
7.2.1.1 Closethemicrometeronthescrew-thread-pitchwire
anvil, in accordance with 7.6.2.3 or 7.6.3.3 as appropriate,
or the plug gage in accordance with the calibration procedure
result in ten zero readings. The condition of zero reading is
of 7.6.2 or 7.6.3 as appropriate.
satisfied when examinations with a low-power magnifying
7.2.1.2 Observe and record the thickness indicated.
glass show that at least 66 % of the width of the zero
7.2.1.3 Move the screw-thread-pitch wire or the plug gage
graduation mark on the barrel coincides with at least 66 % of
to a different position between the presser foot and the anvil
the width of the reference mark.
and repeat 7.2.1.1 and 7.2.1.2.
7.5.2 Proper maintenance of a machinist’s micrometer may
7.2.1.4 If the difference between any pair of readings is
require adjusting the instrument for wear of the micrometer
greater than 0.1 mil, the surfaces are NOT parallel.
screw so that the spindle has no perceptible lateral or longitu-
7.3 Lacking a detailed procedure supplied by the instrument
dinal looseness yet rotates with a torque load of less than 0.25
manufacturer, confirm the requirements for parallelism of
ozf–in.Ifthisisnotachievableafterdisassembly,cleaning,and
dial-type micrometers given in 6.3.1.2 by placing a hardened
lubrication, replace the instrument.
steelball(suchasisusedinaballbearing)ofsuitablediameter
7.5.3 After the zero reading has been checked, use the
between the presser foot and the anvil. Mount the ball in a
calibration procedure of 7.6.2 or 7.6.3 (as appropriate for the
fork-shaped holder to allow the ball to be conveniently moved
machinist’s micrometer under examination) to check for maxi-
from one location to another between the presser foot and the
mum acceptable error in the machinist’s micrometer screw.
anvil. The balls used commercially in ball bearings are almost
7.5.3.1 Use selected feeler-gage blades with known thick-
perfect spheres having diameters constant within a few micro-
nesses to within 60.02 mil to check micrometers calibrated in
inches.
English units at approximately 2, 5, and 10-mil points. Use
NOTE 2—Exercise care with this procedure. Calculations using the
standard gage blocks at points greater than 10 mil.
equations in X1.3.2 show that the use of a 24-oz weight on a ball between
7.5.3.2 At each point checked, take ten readings. Calculate
the hardened surfaces of presser foot and anvil can result in dimples in the
the arithmetic mean of these ten readings.
anvil or presser foot surfaces caused by exceeding the yield stress of the
surfaces. 7.5.3.3 The machinist’s micrometer screw error is within
requirements if the difference between the mean value of
7.3.1 Observe and record the diameter as measured by the
7.5.3.2 and the gage block (or feeler-gage blade) thickness is
micrometer at one location.
not more than 0.1 mil.
7.3.2 Move the ball to another location and repeat the
7.5.4 Calibration of Spindle Pressure in Machinist’s Mi-
measurement.
crometer with Ratchet or Friction Thimble:
7.3.3 If the difference between any pair of readings is
7.5.4.1 See Annex A1, which details the apparatus and
greater than 0.1 mil, the surfaces are NOT parallel.
procedure required for this calibration.
7.4 Lacking a detailed procedure supplied by the instrument
manufacturer, confirm the flatness of the anvil and the spindle 7.6 Calibration of Micrometers :
surface of a micrometer or dial gage
...