1、Designation: D4882 05 (Reapproved 2012)Standard 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 o
2、f 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. Scope1.1 This test method covers the determination of the bondstrength of an electrical insulating varn
3、ish 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
4、.NOTE 1Although 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, if any, ofthe safety concerns, if any, associated with its use. It is theresponsibility of the user of this st
5、andard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. A specific precau-tionary statement is given in Section 7.2. Referenced Documents2.1 ASTM Standards:2D115 Test Methods for Testing Solvent Containing Var-nishes Used
6、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Varnishes by the Helical Coil TestD6054 Practice for Conditioning Electrical Insulating Mate-rials for Testing (Withdrawn 2012)32.2 IEC Standard:IEC 61033 Test Me
7、thods 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 f
8、or 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 can provide informationwith regard to the bond strength o
9、f 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 Preca
10、utions7.1 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.8. Test Specimen Preparation8.1 The test specimen is a wound coil made from film-insulated
11、 magnet wire, 28 AWG (0.320 mm). The coil shall be1This 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 Varnishes, Powders and Encapsulat-ing Compounds.Current
12、 edition approved Jan. 1, 2012. Published January 2012. Originallyapproved in 1988. Last previous edition approved in 2005 as D4882 05. DOI:10.1520/D4882-05R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
13、 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.Copyright ASTM In
14、ternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1made 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,
15、may be wrapped around the coiltwo or 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 diameter 2.25 0.05 in. (571mm)Widthofslot .250.05in.(61mm)Number of turns 100 (See Note 2)Nomina
16、l wire diameter 28 AWG (0.320 mm)NOTE 2Instead of 100 turns of a single wire, 50 turns of two parallelwires may be used to provide a bifilar winding.8.1.1 After the coil has been wound, remove it from thewinding equipment and stretch into an oval shape as shown inFig. 4. Twist the coil two full turn
17、s around its longitudinal axisby means of a twisting device as shown in Fig. 3. The twistedcoil formed is about 0.28 in. (7 mm) in diameter and 3.25 to 3.5in. (85 to 90 mm) in length and serves as a substrate for thevarnish.8.2 The type of magnet wire and test conditions shall bemutually agreed upon
18、 between all involved parties.8.3 Prepare six or more specimens for each condition to beinvestigated.8.4 For solvent-containing varnishes, adjust the viscosity ofthe varnish by trial, to produce a dry film build of 0.0017 to0.0021 in. (.043 to .053 mm) on a double-coated copper panelcoated in accord
19、ance with Test Methods D115.8.5 Do not adjust solventless varnishes.8.6 Attach several twisted coils to a rack and immersevertically in the varnish until bubbling stops. Withdraw them at4 6 0.2 in./min (100 6 5 mm/min) and allow them to drainhorizontally for solventless varnishes 10 to 12 min at sta
20、ndardlaboratory atmosphere in accordance with Practice D6054. Forsolvent-containing varnishes drain vertically 10 to 12 min atstandard laboratory atmosphere in accordance with PracticeD6054. Place the coils in an oven in the same position asdrained. Cure at the temperature and for the time recommend
21、edby the manufacturer. Reverse dip the coils following thepreceding steps if testing a solvent-containing varnish.8.7 When testing solventless varnishes the twisted coils aresingle dipped.9. Procedure9.1 Follow the procedure as required in Test Method D2519.10. Report10.1 Report the data as required
22、 in Test Method D2519.11. Precision and Bias511.1 PrecisionData from an interlaboratory study of thistest method are as follows:Data from six laboratories, 10 individual values from eachlaboratory per condition tested.Tested at 25 CMean 51 lbf (227 N)Standard Deviation 8.1 lbf (36 N)95 % Confidence
23、level 15.9 lbf (71 N)Tested at 150 CMean 31 lbf (138 N)Standard Deviation 4.4 lbf (20 N)95 % Confidence level 8.6 lbf (38 N)11.2 BiasThis test method has no bias because the valuefor bond strength of electrical insulating varnishes by thetwisted coil test is defined solely in terms of this test meth
24、od.5Supporting data are available from ASTM Headquarters. Request RR:D-9-1027.FIG. 1 Coil WinderFIG. 2 Coil Winder, Front ViewD4882 05 (2012)212. Keywords12.1 bond strength; electrical insulating; magnet wire;twisted coil; varnishASTM International takes no position respecting the validity of any pa
25、tent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revisio
26、n at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your com
27、ments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyright
28、ed by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 3 Coil TwisterFIG. 4 Oval-Shaped CoilD4882 05 (2012)3
