ASTM D4882-97

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.

General Information

• Status: Historical
• Publication Date: 09-Sep-2001
• ICS: 29.035.60 - Varnished fabrics
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.01 - Electrical Insulating Products

Relations

• Replaced By: ASTM D4882-01 - Standard Test Method for Bond Strength of Electrical Insulating Varnishes by the Twisted-Coil Test
• Effective Date: 10-Sep-2001
• Referred By: ASTM D1711-22 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 10-Sep-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4882 – 97 An American National Standard
Standard Test Method for
Bond Strength of Electrical Insulating Varnishes by the
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 4. Summary of Test Method
1.1 This test method covers the determination of the bond 4.1 Flexural strength tests are made on twisted coils to
strength of an electrical insulating varnish when applied to a determine the force required to break the coils under specific
twisted coil of film-insulated magnet wire. The use of a conditions.
particular type of film-insulated wire will show the values for
5. Significance and Use
that combination of film coating and varnish.
5.1 Values obtained by flexural test can provide information
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 with regard to the bond strength of the particular varnish in
combination with a particular type of magnet wire, when
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- measured under conditions described in this test method.
bility of regulatory limitations prior to use. A specific precau-
6. Apparatus
tionary statement is given in Section 7.
6.1 Coil winder as shown in Fig. 1 and Fig. 2.
1.3 The values stated in inch-pound units are the standard.
6.2 Coil Twister as shown in Fig. 3.
The values given in parentheses are for information only.
6.3 Test apparatus as described in Test Method D 2519.
NOTE 1—Although this standard and IEC 61033, Method C differ in
approach or detail, data obtained using either are technically equivalent.
7. Safety Precautions
7.1 Do not use varnish at temperatures above the flash point
2. Referenced Documents
when inadequate ventilation and the possibility of flames or
2.1 ASTM Standards:
sparks exist. Store varnish in sealed containers. These precau-
D 115 Test Methods for Testing Solvent Containing Var-
2 tions shall also apply to the handling of the required solvents
nishes Used for Electrical Insulation
and reagents.
D 2519 Test Method for Bond Strength of Electrical Insu-
lating Varnishes by the Helical Coil Test
8. Test Specimen Preparation
D 6054 Practice for Conditioning Electrical Insulating Ma-
8.1 The test specimen is a wound coil made from film-
terials for Testing
insulated magnet wire, 28 AWG (0.320 mm). The coil shall be
2.2 IEC Standard:
made by means of suitable winding equipment as shown in Fig.
IEC 61033 Test Methods for the Determination of Bond
1. To prevent opening of the coil after removal from the
Strength of Impregnating Agents to an Enamelled Wire
winding equipment, each end of the magnet wire, or short
Substrate
pieces of film-insulated wire, may be wrapped around the coil
two or three times. For this purpose the winding equipment is
3. Terminology
provided with appropriate notches as shown in Fig. 2. For
3.1 Definitions of Terms Specific to This Standard:
winding the coil the following dimensions apply:
3.1.1 bond strength, n—a measure of the force required to
Winding diameter 2.25 6 0.05 in. (57 6 1 mm)
separate surfaces which have been bonded together.
Width of slot .25 6 0.05 in. (6 6 1 mm)
Number of turns 100 (See Note 2)
Nominal wire diameter 28 AWG (0.320 mm)
This test method is under the jurisdiction of ASTM Committee D-9 on
NOTE 2—Instead of 100 turns of a single wire, 50 turns of two parallel
Electrical and Electronic Insulating Materials and is the direct responsibility of
wires may be used to provide a bifilar winding.
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders, and Encapsu-
lating Compounds.
8.1.1 After the coil has been wound, remove it from the
Current edition approved Sept. 10, 1997. Published February 1998. Originally
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