1、Designation: D 349 07An American National StandardStandard Test Methods forLaminated Round Rods Used for Electrical Insulation1This standard is issued under the fixed designation D 349; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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.1. Scope*1.1 These test methods cover the procedures for testing rigidround rods used in electrical insulation. Th
3、ese round rodsinclude many types made from fibrous sheets of basic materi-als, such as cellulose, glass, or nylon in the form of paper,woven fabrics, or mats, bonded together by natural or syntheticresins, or by adhesives. Such round rods include vulcanizedfiber and thermosetting laminates as well a
4、s round rods madefrom cast, molded, or extruded natural or synthetic resins, withor without fillers or reinforcing materials.1.2 The procedures appear in the following sections:SectionCompressive strength (axial) 20-25Density 28-30Dielectric strength 31-39Flexural strength 13-19Tensile strength 7-12
5、Water absorption 26-271.3 The values stated in inch-pound units are to be regardedas the standard.1.4 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
6、 practices and determine the applica-bility of regulatory limitations prior to use. For a specificwarning statement see 36.2.2. Referenced Documents2.1 ASTM Standards:2D 149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Powe
7、r FrequenciesD 570 Test Method for Water Absorption of PlasticsD 668 Test Methods of Measuring Dimensions of RigidRods and Tubes Used for Electrical InsulationD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 1711 Terminology Relating to Electrical
8、InsulationD 6054 Practice for Conditioning Electrical Insulating Ma-terials for Testing3. Terminology3.1 DefinitionsUse Terminology D 1711 for definitions ofterms used in these test methods and associated with electricalor electronic insulation materials.4. Selection of Test Specimens4.1 Specimens f
9、or tests shall be selected from portions ofmaterial that are free of obvious defects unless the purpose ofthe test is to evaluate the effect of these defects.5. Conditioning5.1 In order to eliminate the effects of previous history ofhumidity exposure and to obtain reproducible results (Note 1),in al
10、l cases of dispute give the test specimens of laminated rodsa conditioning treatment for physical test as follows:5.1.1 Tensile, Flexural, and Compressive Strengths, andDensityPrior to test, condition the machined specimens inaccordance with Procedure B of Practice D 6054. All speci-mens shall be te
11、sted at room temperature maintained at 23 65 C.NOTE 1Conditioning of specimens may be undertaken: (a) for thepurpose of bringing the material into equilibrium with normal or averageroom conditions of 23 C and 50 % relative humidity; (b) simply to obtainreproducible results, irrespective of previous
12、history of exposure; or (c)tosubject the material to abnormal conditions of temperature or humidity inorder to predict its service behavior.The conditions given here to obtain reproducible results may givephysical values somewhat higher or somewhat lower than values underequilibrium at normal condit
13、ions, depending upon the particular materialand test. To ensure substantial equilibrium under normal conditions ofhumidity and temperature, however, will require from 20 to 100 days ormore depending upon thickness and type of material and its previous1These test methods are under the jurisdiction of
14、 ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.07 on Flexible and Rigid Insulating Materials.Current edition approved Feb. 1, 2007. Published February 2007. Originallyapproved in 1932. Last previous edition approved in 2004 a
15、s D 349 99(2004).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 Changes section appears at th
16、e end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.history. Consequently, conditioning for reproducibility must of necessitybe used for general purchase specifications and product control tests.6. Dimensional Measu
17、rements6.1 Make dimensional measurements of rods in accordancewith Test Methods D 668.TENSILE STRENGTH7. Significance and Use7.1 This test method is designed to provide data for thecontrol and specification of materials and for characterizationpurposes in research and development of new materials.Te
18、nsile properties may vary with the size of specimens and thespeed of testing. Consequently, these factors along with othersnoted herein must be controlled where precise comparativeresults are desired.8. Apparatus8.1 Any testing machine may be used provided it is accurateto 1 % of the lowest breaking
19、 force to be applied. Use jawswhich tighten under load, such as wedge grip jaws, with thespecimen properly aligned.9. Test Specimens9.1 Prepare the test specimen as shown in Fig. 1. The length,L, is as shown in Table 1. Machine a groove around thespecimen at the center of its length so that the diam
20、eter of themachined portion is 60 % of the original nominal diameter.This groove consists of a straight section 214 in. (57 mm) inlength with a radius of 3 in. (76 mm) at each end joining it tothe outside diameter.10. Procedure10.1 Adjust the crosshead speed of the testing machine notto exceed 0.050
21、 in. (1.27 mm)/min when running idle and testfive specimens.11. Report11.1 Report the following information:11.1.1 The average diameter of the specimen, expressed tothe nearest 0.001 in. (0.0254 mm), determined from at leasttwo measurements 90 apart,11.1.2 The average diameter of the reduced section
22、, ex-pressed to the nearest 0.001 in. (0.025 mm), determined fromat least two measurements 90 apart,11.1.3 Crosshead speed in inches per minute (or millime-tres).11.1.4 The breaking load of each specimen in pounds-force(or newtons),11.1.5 The tensile strength of each specimen in pounds-force per squ
23、are inch, (or pascals), and11.1.6 The room temperature in degrees Celsius.12. Precision and Bias12.1 PrecisionThis test method has been in use for manyyears, but no statement of precision has been available and noactivity is planned to develop such a statement.12.2 BiasA statement of bias is not app
24、licable in view ofthe lack of a standard reference material for this property.FLEXURAL STRENGTH13. Significance and Use13.1 Flexural strength data are useful for the control andspecification of materials and to provide guidance in the designof electrical equipment. Flexural properties may vary with
25、thesize of the specimens and the speed of testing. Consequently,these factors, together with others noted herein, must becontrolled where precise comparative results are desired.14. Apparatus14.1 Any testing machine may be used provided it isaccurate to 1 % of the lowest breaking force to be applied
26、.15. Test Specimens15.1 Prepare the test specimen with a diameter equal to thatof the rod and a length eight times the diameter, plus 1 in. (25.4mm) for rods under12 in. (12.7 mm) in diameter. For rods overMetric Equivalentsin. mm2 50.8214 57.13 76.2312 88.9FIG. 1 Diagram Showing Location of Rod Ten
27、sion TestSpecimen in Testing MachineD34907212 in. and up to 2 in. (50.8 mm) in diameter, machinespecimens to a diameter of12 in. and cut to a length of 6 in.(152.4 mm).15.2 When the rod being tested is not circumferentiallyisotropic, prepare specimens for testing in both of the principaldirections,
28、and identify them as to directionality. This particu-larly includes rods machined from stripmolded or sheet stock.16. Procedure16.1 Test five specimens for each laminate orientation, eachas a simple beam loaded at the center. The distance between thesupports shall be eight times the diameter of the
29、rod. Thesupports shall have contact edges rounded to a radius of18 in.(3.2 mm). Adjust the crosshead speed of the testing machinenot to exceed an idle speed of 0.050 in./min (1.27 mm/min) andapply the load through a steel block having a semi-circularcontact edge of the same radius as the rod, with e
30、dges roundedto a radius of18 in. (3.2 mm).17. Calculation17.1 Calculate the maximum fiber stress, S, as follows:S 5 8 WL/pd3(1)where:W = breaking load, lbf (N),L = distance between supports, in. (mm), andd = diameter, in (mm).18. Report18.1 Report the following information:18.1.1 The diameter of the
31、 specimen expressed to thenearest 0.001 in. (0.0254 mm), determined from at least twomeasurements 90 apart,18.1.2 Crosshead speed in inches per minute (or millime-tres),18.1.3 The breaking load of each specimen in pounds-force(or newtons),18.1.4 The maximum fiber stress S, in pounds-force persquare
32、inch (pascals), and18.1.5 The direction of loading relative to the direction ofthe laminate if the rods are ground from strip-molded stock,sheet stock, and vulcanized fiber.19. Precision and Bias19.1 PrecisionThis test method has been in use for manyyears, but no statement of precision has been avai
33、lable and noactivity is planned to develop such a statement.19.2 BiasA statement of bias is not applicable in view ofthe lack of a standard reference material for this property.COMPRESSIVE STRENGTH (AXIAL)20. Significance and Use20.1 Compression tests, properly interpreted, provide rea-sonably accur
34、ate information with regard to the compressiveproperties of rigid round rods when employed under conditionsapproximating those under which the tests are made. Thecompressive strength values may vary with the size of the rigidround rod, and with temperature and atmospheric conditions.Compression test
35、s may provide data for research and develop-ment, engineering design, quality control, and acceptance orrejection under specifications.21. Apparatus21.1 Any testing machine may be used provided it isaccurate to 1 % of the lowest breaking force to be applied. Oneend of the specimen shall bear upon an
36、 accurately centeredspherical bearing block, located, whenever practicable, at thetop. The metal bearing plates shall be directly in contact withthe ends of the test specimen.22. Test Specimens22.1 Unless otherwise specified in the test method orspecification for that material, test the samples as r
37、eceived. Forrods18 to 1 in. (3.2 to 25.4 mm) in diameter, prepare the testspecimen with a diameter equal to the diameter of the rod, andlength conforming to the following requirements:Diameter, in. (mm)Length, in.(mm)SlendernessRatio18 to14 (3.2 to 6.4) incl12 (12.7) 16 to 8Over14 to12 (6.4 to 12.7)
38、 incl 1 (25.4) 16 to 8Over12 to 1 (12.7 to 25.4) incl 2 (50.8) 16 to 822.2 For rods over 1 in. (25.4 mm) in diameter, specimensare standard12 by12 by 1-in. (12.7 by 12.7 by 25.4-mm) rightparallelepiped, cut from the rods so as to be representative oftheir cross sections both at the center and near t
39、he edges.TABLE 1 Dimensions of Rod SpecimensNominal Diameter,in. (mm)Length of Radial Sections2 RS, in. (mm)Total Calculated MinimumLength of Specimen,in. (mm)Standard Length, L, of Speci-men to be Used for 312 in.(88.9 mm) JawsA18 (3.2) 0.773 (19.63) 14.02 (35.61) 15 (381.0)316 (4.8) 0.946 (24.03)
40、14.20 (36.06) 15 (381.0)14 (6.4) 1.091 (27.71) 14.34 (36.42) 15 (381.0)38 (9.5) 1.333 (33.86) 14.58 (37.03) 15 (381.0)12 (12.7) 1.563 (38.01) 14.79 (37.56) 15.75 (400.0)58 (15.9) 1.714 (43.56) 14.96 (37.99) 15.75 (400.0)34 (19.0) 1.813 (46.05) 15.12 (38.40) 15.75 (400.0)78 (22.1) 2.019 (51.28) 15.27
41、 (38.78) 15.75 (400.0)1 (25.4) 2.154 (54.71) 15.40 (39.11) 16.5 (414.0)114 (31.8) 2.398 (60.90) 15.65 (39.75) 16.5 (414.0)112 (38.0) 2.615 (66.42) 15.87 (40.31) 16.5 (414.0)134 (44.5) 2.812 (70.41) 16.06 (40.79) 16.5 (414.0)2 (50.8) 2.993 (76.02) 16.24 (41.25) 17 (432.0)AFor other jaws greater than
42、312 in. (88.9 mm), the standard length shall be increased by twice the length of the jaw minus 7 in. (177.8 mm). The standard length permitsa slippage of approximately14 to12 in. (6.35 to 12.7 mm) in each jaw while maintaining maximum length of jaw grip.D34907322.3 Accurately cut or grind the ends o
43、f each specimenparallel to each other.23. Procedure23.1 Adjust the crosshead speed of the testing machine notto exceed an idle speed of 0.050 in./min (1.27 mm/min), andtest five specimens with the load applied perpendicular to thefaces or ends of the specimen.23.2 Discard specimens that break at som
44、e obvious flaw andmake retests unless such flaws constitute a variable, the effectof which it is desired to study.24. Report24.1 Report the following information:24.1.1 The diameter of the specimen expressed to thenearest 0.001 in. (0.0254 mm), determined from at least twomeasurements 90 apart,24.1.
45、2 The load on each specimen in pounds at the first signof rupture, and24.1.3 The compressive strength in pounds-force per squareinch (or pascals) calculated from the data obtained on theapplication of the load perpendicular to the face of thespecimen.25. Precision and Bias25.1 PrecisionThis test met
46、hod has been in use for manyyears, but no statement of precision has been available and noactivity is planned to develop such a statement.25.2 BiasA statement of bias is not applicable in view ofthe lack of a standard reference material for this property.WATER ABSORPTION26. Significance and Use26.1
47、The moisture content of a rigid round rod has a definiteinfluence on the electrical properties, mechanical strength,dimensional stability, and appearance. The effect upon theseproperties of changes in moisture content, due to waterabsorption, depends largely upon the inherent properties of therigid
48、round rod. The rate of water absorption may be widelydifferent through each edge and surface. A water absorptiondetermination will provide data useful for research and devel-opment, engineering design, quality control, and acceptance orrejection under specifications.27. Procedure27.1 Determine and r
49、eport the rate of water absorption inaccordance with Test Method D 570, immersing specimens for24 h in distilled water at 23 6 1 C after preliminaryconditioning for1hat105to110C.27.2 For some types of materials, or for special applications,it may be desirable to employ longer periods of water immer-sion in order to evaluate performance. In these cases, the reportshall indicate the exact conditioning procedure.DENSITY28. Significance and Use28.1 Density measurements are convenient means of iden-tifying materials in terms of composition.
