ASTM D4882-05(2012)
(Test Method)Standard Test Method for Bond Strength of Electrical Insulating Varnishes by the Twisted-Coil Test
Standard Test Method for Bond Strength of Electrical Insulating Varnishes by the Twisted-Coil Test
SIGNIFICANCE AND USE
Values obtained by flexural test can provide information with regard to the bond strength of the particular varnish in combination with a particular type of magnet wire, when measured under conditions described in this test method.
SCOPE
1.1 This test method covers the determination of the bond strength of an electrical insulating varnish when applied to a twisted coil of film-insulated magnet wire. The use of a particular type of film-insulated wire will show the values for that combination of film coating and varnish.
1.2 This standard does not purport to address all, if any, 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. A specific precautionary statement is given in Section 7.
1.3 The values stated in inch-pound units are the standard. The values given in parentheses are for information only.
Note 1—Although this standard and Method C of IEC 61033 differ in approach or detail, data obtained using either are technically equivalent.
General Information
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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D4882 − 05 (Reapproved 2012)
Standard Test Method for
Bond Strength of Electrical Insulating Varnishes by the
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Twisted-Coil Test
This standard is issued under the fixed designation D4882; 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.
1. Scope 2.2 IEC Standard:
IEC 61033 Test Methods for the Determination of Bond
1.1 This test method covers the determination of the bond
Strength of Impregnating Agents to an Enamelled Wire
strength of an electrical insulating varnish when applied to a
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Substrate
twisted coil of film-insulated magnet wire. The use of a
particular type of film-insulated wire will show the values for
3. Terminology
that combination of film coating and varnish.
3.1 Definitions of Terms Specific to This Standard:
1.2 The values stated in inch-pound units are the standard.
3.1.1 bond strength, n—a measure of the force required to
The values given in parentheses are for information only.
separate surfaces which have been bonded together.
NOTE 1—Although this standard and Method C of IEC 61033 differ in
3.2 Refer to Terminology D1711 for definitions of other
approach or detail, data obtained using either are technically equivalent.
terms.
1.3 This standard does not purport to address all, if any, of
4. Summary of Test Method
the safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.1 Flexural strength tests are made on twisted coils to
priate safety and health practices and determine the applica- determine the force required to break the coils under specific
bility of regulatory limitations prior to use. A specific precau- conditions.
tionary statement is given in Section 7.
5. Significance and Use
5.1 Values obtained by flexural test can provide information
2. Referenced Documents
with regard to the bond strength of the particular varnish in
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2.1 ASTM Standards:
combination with a particular type of magnet wire, when
D115 Test Methods for Testing Solvent Containing Var-
measured under conditions described in this test method.
nishes Used for Electrical Insulation
D1711 Terminology Relating to Electrical Insulation
6. Apparatus
D2519 Test Method for Bond Strength of Electrical Insulat-
6.1 Coil winder as shown in Fig. 1 and Fig. 2.
ing Varnishes by the Helical Coil Test
6.2 Coil Twister as shown in Fig. 3.
D6054 Practice for Conditioning Electrical Insulating Mate-
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rials for Testing (Withdrawn 2012)
6.3 Test apparatus as described in Test Method D2519.
7. Safety Precautions
7.1 It is unsafe to use varnish at temperatures above the
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This test method is under the jurisdiction of ASTM Committee D09 on
flash point without adequate ventilation, especially if the
Electrical and Electronic Insulating Materials and is the direct responsibility of
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders and Encapsulat-
possibility exists that flames or sparks are present. Store
ing Compounds.
varnish in sealed containers.
Current edition approved Jan. 1, 2012. Published January 2012. Originally
approved in 1988. Last previous edition approved in 2005 as D4882 – 05. DOI:
8. Test Specimen Preparation
10.1520/D4882-05R12.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
8.1 The test specimen is a wound coil made from film-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
insulated magnet wire, 28AWG (0.320 mm). The coil shall be
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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The last approved version of this historical standard is referenced on
Available from American National Standards Institute, 25 W. 43rd St., 4th
www.astm.org.
Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4882 − 05 (2012)
8.1.1 After the coil has been wound, remove it from the
winding equipment and stretch into an oval shape as shown in
Fig. 4. Twist the coil two full turns around its longitudinal axis
by means of a twisting device as shown in Fig. 3. The twisted
coilformedisabout0.28in.(7mm)indiameterand3.25to3.5
in. (85 to 90 mm) in length and serves as a substrate for the
varnish.
8.2 The type of magnet wire and test conditions shall be
mutually agreed upon between all involved parties.
8.3 Prepare six or more specimens for each condition to be
investigated.
8.4 For solvent-containing varnishes, adjust the viscosity of
the varnish by trial, to produce a dry film build of 0.0017 to
0.0021
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