ASTM D2519-07

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An American National Standard
Designation:D2519–07
Standard Test Method for
Bond Strength of Electrical Insulating Varnishes by the
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Helical Coil Test
This standard is issued under the fixed designation D2519; 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* 3.1.1 bond strength—a measure of the force required to
separate surfaces which have been bonded together.
1.1 This test method covers determination of the bond
3.2 Definitions of Terms Specific to This Standard:
strength of an electrical insulating varnish when applied to a
3.2.1 event time—the time between initial application of a
helical coil. The helical coil can be made from bare aluminum
physical or electrical stress and failure of the specimen under
or copper wire or from film or fiber-insulated magnet wire.
test.
Helical coils made from bare aluminum or bare copper wire
3.2.2 response time—the time required for an indicating or
will yield values of bond strength for the varnish when applied
recording device to react to change in stress on a specimen
to bare metal conductors. The use of film or fiber-insulated
under test.
magnet wire will show values for that particular combination
of insulation and varnish.
4. Summary of Test Method
1.2 The values stated in SI units are to be regarded as the
4.1 Flexural strength tests are made on varnish-treated
standard. The values given in parentheses are for information
helical coils to determine the force required to break the coil
only.
under specified conditions.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
5.1 Values obtained by flexural tests can provide informa-
priate safety and health practices and determine the applica-
tion with regard to the bond strength of the particular varnish,
bility of regulatory limitations prior to use. See Section 7.
in combination with a particular wire, when measured under
conditions described in this test method.
2. Referenced Documents
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2.1 ASTM Standards:
6. Apparatus
D115 Test Methods for Testing Solvent Containing Var-
6.1 Tensile Testing Machine—Useanadjustable-speeddrive
nishes Used for Electrical Insulation
and a suitable instrument for measuring force to break the
D1711 Terminology Relating to Electrical Insulation
specimen. Available tensile testing machines or an accurate
D6054 Practice for Conditioning Electrical Insulating Ma-
springgaugeandaseparateadjustable-speeddrivearesuitable.
terials for Testing
Tocovertherangeofloadstrengthvalueswhicharecommonly
E691 Practice for Conducting an Interlaboratory Study to
encountered it is recommended that a multirange tester be
Determine the Precision of a Test Method
used.
6.1.1 It has been found that gages rated 5, 25, 150, and
3. Terminology
500 N (1, 5, 30, and 100 lbf) are adequate to cover the range of
3.1 Definitions: For definitions of other terms relating to
varnishes.
electrical insulation, see Terminology D1711.
6.2 Test Fixture—The test fixture consists of two rollers,
attached to a common frame, and a 90° V-block. One part,
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This test method is under the jurisdiction of ASTM Committee D09 on
either the rollers or the V-block, is held stationary while the
Electrical and Electronic Insulating Materials and is the direct responsibility of
other part is moved. No friction contact which will affect this
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders and Encapsulat-
ing Compounds.
movement is allowed. The general shape and the relative
Current edition approved May 1, 2007. Published June 2007. Originally
position of these parts are shown in Fig. 1. The rollers have a
approved in 1966. Last previous edition approved in 2002 as D2519 – 02. DOI:
diameter of 9.5 mm (0.375 in.) at the center and are parallel
10.1520/D2519-07.
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having a center-to-center distance of 44.5 mm (1.75 in.). The
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
90° V-block has a radius at the apex of 0.8 mm (0.03 in.).
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
*A Summary of Changes section appears at the end of this standard.
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D2519–07
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