1、Designation: D4882 17Standard 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 ye
2、ar 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
3、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.NOTE 1Although t
4、his 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-
5、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-izat
6、ion 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-n
7、ishes 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Varnishes by the Helical Coil TestD6054 Practice for Conditioning Electrical Insulating Mate-rials for Testing (Withdrawn 2012)32.2 IEC Standard:IEC 61
8、033 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 Terminol
9、ogy 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 st
10、rength 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. Safe
11、ty 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
12、 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 r
13、eferenced 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 reference
14、d 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
15、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
16、) Committee.18. 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
17、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 diameter 2.25 0.05 in. (57.21mm)Widthofslot
18、 .250.05in.(6.41mm)Number of turns 100 (See Note 2)Nominal wire diameter 28 AWG (0.320 mm)NOTE 2Instead of 100 turns of a single wire, 50 turns of two parallelwires are allowable to provide a bifilar winding.8.1.1 After the coil has been wound, remove it from thewinding equipment and stretch into an
19、 oval shape as shown inFig. 4. Twist the coil two full turns around its longitudinal axisby means of a twisting device as shown in Fig. 3. The twistedcoil formed is about 0.28 in. (7.1 mm) in diameter and 3.25 to3.5 in. (82.6 to 88.9 mm) in length and serves as a substrate forthe varnish.8.2 The typ
20、e of magnet wire and test conditions shall bemutually agreed upon 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.
21、(.043 to .053 mm) on a double-coated copper panelcoated in accordance 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 t
22、o drainhorizontally for solventless varnishes 10 to 12 min at standardlaboratory 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 posit
23、ion asdrained. Cure at the temperature and for the time recommendedby 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 require
24、d in Test Method D2519.10. Report10.1 Report the data as required 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 CMea
25、n 51 lbf (227 N)Standard Deviation 8.1 lbf (36 N)95 % Confidence 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
26、thetwisted coil test is defined solely in terms of this test method.5Supporting data are available from ASTM Headquarters. Request RR:D-9-1027.FIG. 1 Coil WinderFIG. 2 Coil Winder, Front ViewD4882 17212. Keywords12.1 bond strength; electrical insulating; magnet wire;twisted coil; varnishSUMMARY OF C
27、HANGESCommittee D09 has identified the location of selected changes to this standard since the last issue(D4882 05 (2012) that may impact the use of this standard. (Approved Nov. 1, 2017.)(1) Removed non-mandatory language from 5.1 and 8.1. (2) Updated unit conversions in 8.1 and 8.1.1.FIG. 3 Coil T
28、wisterFIG. 4 Oval-Shaped CoilD4882 173ASTM International takes no position respecting the validity of any patent 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 r
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