ASTM_D_4882_-_17.pdf

Designation:D488217Standard Test Method forBond Strength of Electrical Insulating Varnishes by theTwisted-Coil Test1This standard is issued under the fixed designation D4882;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,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.1.Scope*1.1 This test method covers the determination of the bondstrength of an electrical insulating varnish when applied to atwisted coil of film-insulated magnet wire.The use of aparticular type of film-insulated wire will show the values forthat combination of film coating and varnish.1.2 The values stated in inch-pound units are the standard.The values given in parentheses are for information only.NOTE1Although this standard and Method C of IEC 61033 differ inapproach or detail,data obtained using either are technically equivalent.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Aspecific precautionary statement is given in Section 7.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D115 Test Methods for Testing Solvent Containing Var-nishes Used for Electrical InsulationD1711 Terminology Relating to Electrical InsulationD2519 Test Method for Bond Strength of Electrical Insulat-ing Varnishes by the Helical Coil TestD6054 Practice for Conditioning Electrical Insulating Mate-rials for Testing(Withdrawn 2012)32.2IEC Standard:IEC 61033 Test Methods for the Determination of BondStrength of Impregnating Agents to an Enamelled WireSubstrate43.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 bond strength,na measure of the force required toseparate surfaces which have been bonded together.3.2 Refer to Terminology D1711 for definitions of otherterms.4.Summary of Test Method4.1 Flexural strength tests are made on twisted coils todetermine the force required to break the coils under specificconditions.5.Significance and Use5.1 Values obtained by flexural test provides informationwith regard to the bond strength of the particular varnish incombination with a particular type of magnet wire,whenmeasured under conditions described in this test method.6.Apparatus6.1 Coil winder as shown in Fig.1 and Fig.2.6.2 Coil Twister as shown in Fig.3.6.3 Test apparatus as described in Test Method D2519.7.Safety Precautions7.1 It is unsafe to use varnish at temperatures above theflash point without adequate ventilation,especially if thepossibility exists that flames or sparks are present.Storevarnish in sealed containers.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.01 on Electrical Insulating Products.Current edition approved Nov.1,2017.Published November 2017.Originallyapproved in 1988.Last previous edition approved in 2012 as D4882 05(2012).DOI:10.1520/D4882-17.2For 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 this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute,25 W.43rd St.,4thFloor,New York,NY 10036.*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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 8.Test Specimen Preparation8.1 The test specimen is a wound coil made from film-insulated magnet wire,28 AWG(0.320 mm).The coil shall bemade by means of suitable winding equipment as shown in Fig.1.To prevent opening of the coil after removal from thewinding equipment,each end of the magnet wire,or shortpieces of film-insulated wire,are wrapped around the coil twoor three times.For this purpose the winding equipment isprovided with appropriate notches as shown in Fig.2.Forwinding the coil the following dimensions apply:Winding diameter2.25 0.