ASTM D4882-01
(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
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 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 to be regarded as 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.
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An American National Standard
Designation:D4882–01
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 D 4882; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 bond strength, n—a measure of the force required to
separate surfaces which have been bonded together.
1.1 This test method covers the determination of the bond
3.2 Refer to Terminology D 1711 for definitions of other
strength of an electrical insulating varnish when applied to a
terms.
twisted coil of film-insulated magnet wire. The use of a
particular type of film-insulated wire will show the values for
4. Summary of Test Method
that combination of film coating and varnish.
4.1 Flexural strength tests are made on twisted coils to
1.2 This standard does not purport to address all, if any, of
determine the force required to break the coils under specific
the safety concerns, if any, associated with its use. It is the
conditions.
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. A specific precau-
5.1 Values obtained by flexural test can provide information
tionary statement is given in Section 7.
with regard to the bond strength of the particular varnish in
1.3 The values stated in inch-pound units are the standard.
combination with a particular type of magnet wire, when
The values given in parentheses are for information only.
measured under conditions described in this test method.
NOTE 1—Although this standard and Method C of IEC 61033 differ in
approach or detail, data obtained using either are technically equivalent. 6. Apparatus
6.1 Coil winder as shown in Fig. 1 and Fig. 2.
2. Referenced Documents
6.2 Coil Twister as shown in Fig. 3.
2.1 ASTM Standards:
6.3 Test apparatus as described in Test Method D 2519.
D 115 Test Methods for Testing Solvent Containing Var-
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nishes Used for Electrical Insulation
7. Safety Precautions
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D 1711 Terminology Relating to Electrical Insulation
7.1 It is unsafe to use varnish at temperatures above the
D 2519 Test Method for Bond Strength of Electrical Insu-
flash point without adequate ventilation, especially if the
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lating Varnishes by the Helical Coil Test
possibility exists that flames or sparks are present. Store
D 6054 Practice for Conditioning Electrical Insulating Ma-
varnish in sealed containers.
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terials for Testing
2.2 IEC Standard: 8. Test Specimen Preparation
IEC 61033 Test Methods for the Determination of Bond
8.1 The test specimen is a wound coil made from film-
Strength of Impregnating Agents to an Enamelled Wire
insulated magnet wire, 28AWG (0.320 mm). The coil shall be
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Substrate
madebymeansofsuitablewindingequipmentasshowninFig.
1. To prevent opening of the coil after removal from the
3. Terminology
winding equipment, each end of the magnet wire, or short
3.1 Definitions of Terms Specific to This Standard:
pieces of film-insulated wire, may be wrapped around the coil
two or three times. For this purpose the winding equipment is
1 provided with appropriate notches as shown in Fig. 2. For
ThistestmethodisunderthejurisdictionofASTMCommitteeD9onElectrical
and Electronic Insulating Materials and is the direct responsibility of Subcommittee winding the coil the following dimensions apply:
D09.01onElectricalInsulatingVarnishes,Powders,andEncapsulatingCompounds.
Winding diameter 2.25 6 0.05 in. (57 6 1 mm)
Current edition approved Sept. 10, 2001. Published November 2001. Originally
Width of slot .25 6 0.05 in. (6 6 1 mm)
published as D 4882 – 88. Last previous edition D 4882 – 97.
Number of turns 100 (See Note 2)
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Annual Book of ASTM Standards, Vol 10.01.
Nominal wire diameter 28 AWG (0.320 mm)
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Annual Book of ASTM Standards, Vol 10.02.
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NOTE 2—Instead of 100 turns of a single wire, 50 turns of two parallel
Available from American National Standards Institute, 25 W. 43rd St., 4th
wires may be used to provide a bifilar winding.
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
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 in. (.043 to .053 mm) on a double-coated copper panel
coated in accordance with Test Methods D 115.
8.5 For solven
...
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