1、Designation: D 2519 07An American National StandardStandard Test Method forBond Strength of Electrical Insulating Varnishes by theHelical Coil Test1This standard is issued under the fixed designation D 2519; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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*1.
3、1 This test method covers 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
4、 values of bond strength 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
5、are for informationonly.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 prio
6、r to use. See Section 7.2. Referenced Documents2.1 ASTM Standards:2D115 Test Methods for Testing Solvent Containing Var-nishes Used for Electrical InsulationD 1711 Terminology Relating to Electrical InsulationD 6054 Practice for Conditioning Electrical Insulating Ma-terials for TestingE 691 Practice
7、 for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: For definitions of other terms relating toelectrical insulation, see Terminology D 1711.3.1.1 bond strengtha measure of the force required toseparate surfaces which have been bonded toge
8、ther.3.2 Definitions 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 specimenund
9、er test.4. Summary 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
10、the particular 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 a
11、ccuratespring gauge 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 cove
12、r the range ofvarnishes.6.2 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 thismovement is allowed. The general shape
13、 and the relativeposition of these 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.).1This test method is under the jurisdicti
14、on 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 edition approved May 1, 2007. Published June 2007. Originallyapproved in 1966. Last previo
15、us edition approved in 2002 as D 2519 02.2For 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.1*A Summary of Chang
16、es section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 Test Fixture EnclosureFor tests at other than roomtemperature, use an insulated heat-resistant enclosure, designedto fit around the tes
17、t fixture and connected to the tension testingmachine. This enclosure permits a frictionless connectionbetween the test fixture and the instrument that measures thebreaking force. The enclosure is designed with a suitablelocation for holding six or more specimens. It is heated orcooled by a separate
18、 source of uniformly circulating hot or coldair. The temperature control system is capable of returning thetest specimens and the chamber to the test temperature in lessthan 10 min. A thermostatic control, with the measuringthermocouple located within 25 mm (1.0 in.) of the center ofthe coil being t
19、ested, is set to maintain the temperature of thechamber to within 6 2 C of the desired temperature after thetemperature has stabilized.7. Safety Precautions7.1 It is unsafe to use varnish at temperatures above theflash point without adequate ventilation, especially if thepossibility exists that flam
20、es or sparks are present. Storevarnish in sealed containers.8. Test Specimens8.1 The test specimens are 75 mm (3 in.) long coils of No.18 AWG wire, cut from a helix of convenient length which hasbeen wound without space between turns ona6mm(0.25 in.)diameter mandrel. Bend the last loop on each end o
21、f the coil toapproximately 90 to the coil to provide a means of support.Treat the coil with the varnish to be tested. Make the helicalcoils as agreed to by interested parties from one of thefollowing:8.1.1 Bare aluminum wire,8.1.2 Bare copper wire,8.1.3 Film-coated magnet wire, or8.1.4 Fiber-insulat
22、ed magnet wire.NOTE 1A practical method of winding a tight helical coil is to guidethe wire from the rotating reel between folds of a clean cloth onto therotating mandrel using moderate hand tension. Maintain a trailing angle of1 to 5 from a perpendicular to the mandrel. When the wire is cut, the co
23、ilmust be restrained to avoid rapid spring back.8.2 Prepare six or more specimens for each condition to beinvestigated.8.3 Adjust the viscosity of the varnish to be tested, by trial,to produce a dry film build of 0.043 to 0.053 mm (0.0017 to0.0021 in.) on a metal panel double coated in accordance wi
24、thTest Methods D115.8.4 Use solventless varnish in the “as received” condition.8.5 Immerse coils made from bare wire in a solvent of 50 %toluene and 50 % denatured alcohol by weight for 30 min.Remove and dry for 15 min at 100 C before treating withvarnish. Do not clean coils made from insulated wire
25、 beforetreating with varnish.8.6 Attach several coils to a rack and immerse vertically inthe varnish until bubbling stops. Withdraw them at 100 65mm/min (4 60.2 in./min) and allow them to drain 10 to 30 minat the Standard Laboratory Atmosphere in accordance withPractice D 6054. Place the coils in an
26、 oven in the same positionas dipped at the temperature and for the time specified by themanufacturer. For solvent containing varnishes, reverse dip andbake the coils, following the above procedure.9. Procedure9.1 Rate of LoadingAdjust the testing machine to acrosshead speed of 50 mm/min (2 in./min).
27、9.1.1 Position the coils in the test fixture with the center ofthe coils below the V-block. Each coil is broken only once.9.2 Number of SpecimensTest a minimum of five speci-mens for each condition. It is allowable to use one of theoriginal six specimens for adjusting the testing machine.9.3 Selecti
28、on of Test RangeSelect the proper test rangewhich corresponds to the specified rate of loading. The propertest range is the one where the anticipated bond strength will bereached in the middle or upper portion of the test range,whenever possible. For testers with chart recorders it isessential that
29、the test range be selected in such a manner thatthe event time is greater than the response time of the recorder.9.4 Tests at Other than Room Temperature:9.4.1 Adjust the temperature control until the temperature ofthe chamber becomes constant within 6 2 C of the specifiedtest temperature.9.4.2 Plac
30、e one specimen in the test fixture. Place theremaining specimens in the enclosure. Allow the enclosure tostabilize for 5 6 1 min at the test temperature. Break thespecimen in the test fixture as described in 9.1-9.3.9.4.3 Replace broken specimen with an untested specimenfrom within the enclosure. Al
31、low the enclosure to stabilize forapproximately 1 min at the test temperature. Break the speci-men in the test fixture as described in 9.1-9.3.9.4.4 Repeat 9.4.3 for the remaining specimens.10. Report10.1 Report the following information:10.1.1 Description of varnish,10.1.2 Identification of wire us
32、ed,10.1.3 Cure time and temperature for each coat and numberof dips used to prepare the coils, andFIG. 1 Test Fixture for Bond Strength TestD251907210.1.4 The individual values in newtons (pounds-force) ofbond strength and their averages at each test condition.11. Precision and Bias11.1 PrecisionTab
33、le 1 lists the results based on a roundrobin test conducted in accordance with Practice E 691 involv-ing six laboratories and three materials. Each test result was theaverage of five specimens. Each laboratory obtained two testresults for each material.11.2 BiasThis test method has no bias because t
34、he valuefor bond strength of electrical insulating varnishes by thehelical coil test is determined solely in terms of this testmethod.Combined data from six laboratories:Mean = 220.6 N (49.6 lbf)Standard deviation = 41.99 N (66.96 lbf)95 % Confidence level = 82.25 N (613.64 lbf)12. Keywords12.1 bond
35、 strength; helical coil; varnishSUMMARY OF CHANGESCommittee D09 has identified the location of selected changes to this test method since the last issue,D 2519 02, that may impact the use of this test method. (Approved May 1, 2007)(1) Revised Sections 6, 8, and 9.ASTM International takes no position
36、 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 riskof infringement of such rights, are entirely their own responsibility.T
37、his standard is subject to revision 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 In
38、ternational Headquarters. Your comments 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 show
39、n below.This standard is copyrighted 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-
40、9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 1 Results inNewtonsMaterial AverageStandardDeviationRepeatabilityStandardDeviationReproducibilityStandard DeviationRepeatabilityLimitReproducibilityLimitSolvent Varnish 97.21 13.92 1.75 12.81 4.90 35.87Unsaturated Polyester 166.76 34.03 6.26 31.59 17.53 88.45Epoxy 208.43 37.45 10.41 35.48 29.15 99.34D2519073
