1、Designation:D251907(Reapproved 2012)Standard Test Method forBond Strength of Electrical Insulating Varnishes by theHelical Coil Test1This standard is issued under the fixed designation D2519;the number immediately following the designation indicates the year oforiginal adoption or,in the case of rev
2、ision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 This test method co
3、vers determination of the bondstrength of an electrical insulating varnish when applied to ahelical coil.The helical coil can be made from bare aluminumor copper wire or from film or fiber-insulated magnet wire.Helical coils made from bare aluminum or bare copper wirewill yield values of bond streng
4、th for the varnish when appliedto bare metal conductors.The use of film or fiber-insulatedmagnet wire will show values for that particular combinationof insulation and varnish.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.
5、1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.See Section 7.2.Re
6、ferenced Documents2.1 ASTM Standards:2D115 Test Methods for Testing Solvent Containing Var-nishes Used for Electrical InsulationD1711 Terminology Relating to Electrical InsulationD6054 Practice for Conditioning Electrical Insulating Mate-rials for Testing(Withdrawn 2012)3E691 Practice for Conducting
7、 an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 For definitions of other terms relating to electricalinsulation,see Terminology D1711.3.1.2 bond strengtha measure of the force required toseparate surfaces which have been bonded together.3.2 Defi
8、nitions of Terms Specific to This Standard:3.2.1 event timethe time between initial application of aphysical or electrical stress and failure of the specimen undertest.3.2.2 response timethe time required for an indicating orrecording device to react to change in stress on a specimenunder test.4.Sum
9、mary of Test Method4.1 Flexural strength tests are made on varnish-treatedhelical coils to determine the force required to break the coilunder specified conditions.5.Significance and Use5.1 Values obtained by flexural tests can provide informa-tion with regard to the bond strength of the particular
10、varnish,in combination with a particular wire,when measured underconditions described in this test method.6.Apparatus6.1 Tensile Testing MachineUse an adjustable-speed driveand a suitable instrument for measuring force to break thespecimen.Available tensile testing machines or an accuratespring gaug
11、e and a separate adjustable-speed drive are suitable.To cover the range of load strength values which are commonlyencountered it is recommended that a multirange tester beused.6.1.1 It has been found that gages rated 5,25,150,and500 N(1,5,30,and 100 lbf)are adequate to cover the range ofvarnishes.6.
12、2 Test FixtureThe test fixture consists of two rollers,attached to a common frame,and a 90 V-block.One part,either the rollers or the V-block,is held stationary while theother part is moved.No friction contact which will affect this1This test method is under the jurisdiction of ASTM Committee D09 on
13、Electrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.01 on Electrical Insulating Varnishes,Powders and Encapsulat-ing Compounds.Current edition approved April 1,2012.Published April 2012.Originallyapproved in 1966.Last previous edition approved in 2007 a
14、s D2519 07.DOI:10.1520/D2519-07R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of t
15、his historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 movement is allowed.The general shape and the relativeposition of these
16、parts are shown in Fig.1.The rollers have adiameter of 9.5 mm(0.375 in.)at the center and are parallelhaving a center-to-center distance of 44.5 mm(1.75 in.).The90 V-block has a radius at the apex of 0.8 mm(0.03 in.).6.3 Test Fixture EnclosureFor tests at other than roomtemperature,use an insulated heat-resistant enclosure,designedto fit around the test fixture and connected to the tension testingmachine.This enclosure permits a frictionless connectionbetween the test fixture and the instrument