1、Designation: D668 12Standard Test Methods ofMeasuring Dimensions of Rigid Rods and Tubes Used forElectrical Insulation1This standard is issued under the fixed designation D668; 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 These test methods cover the measurement of thedimensions of all rigid rods and tubes used as electricalinsulat
3、ion, the limitations imposed being those of the sizerange of the more common forms of measuring instrumentsused.1.2 Where the number of tests to be made or the specifica-tions covering the rod or tube justify its use, it is acceptable touse an accurately calibrated “go-and-no-go” ring gage ofsuitabl
4、e size.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 prior to use.2. Refer
5、enced Documents2.1 ASTM Standards:2D374 Test Methods for Thickness of Solid Electrical Insu-lation (Withdrawn 2013)3D1711 Terminology Relating to Electrical Insulation3. Terminology3.1 Definitions For definitions of terms used in these testmethods refer to Terminology D1711.4. Significance and Use4.
6、1 These test methods are used to measure the dimensionsof the rod or tube to determine conformance with specificationson full lengths or cut lengths. The measurements can also beused for manufacturing control, determination of uniformity,dimensional stability, and physical and electrical properties
7、ofthe rods and tubes.5. Conditioning5.1 Condition specimens prior to testing for at least 48 h at23 6 1 C and 50 6 2 % relative humidity. Perform tests in aircontrolled at that temperature and humidity.6. Method of Measurement6.1 Make all diameter and wall thickness measurements forspecimens with di
8、mensions 300 mm (12 in.) and under inaccordance with the procedure described in Test MethodsD374 as applicable. Close the micrometer or vernier caliperslowly on the specimen until contact is made without appre-ciable distortion of the specimen. The criterion of contact is theinitial development of f
9、rictional resistance to movement of thespecimen between the micrometer or caliper surfaces. Use asteel tape or steel scale for measurement of length and diametergreater than 300 mm (12 in.).7. Length of Rods or Tubes 300 mm (12 in.) and Underin Length7.1 ApparatusAmachinists micrometer or vernier ca
10、liperof suitable size reading to 0.02 mm or 0.001 in.7.2 Test SpecimensSpecimens shall consist of rods ortubes 300 mm (12 in.) or shorter.7.3 ProcedureMeasure the length of the specimen to thenearest 0.02 mm or 0.001 in. Size permitting, make fourmeasurements at points 90 apart around the circumfere
11、nce ofthe specimen.7.4 ReportReport the average of the measurements takenas the length of the rod or tube.8. Length of Rod or Tubes Over 300 mm (12 in.) inLength8.1 ApparatusSteel tape or steel scale of suitable lengthgraduated in 0.5 mm or164 in.8.2 Test SpecimensSpecimens shall consist of rods ort
12、ubes over 300 mm (12 in.) in length, including full lengths.1These test methods are under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.07 on Flexible and Rigid Insulating Materials.Current edition approve
13、d Nov. 1, 2012. Published November 2012. Originallyapproved in 1942. Last previous edition approved in 2004 as D668 99(2004).DOI: 10.1520/D0668-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandard
14、s 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
15、 West Conshohocken, PA 19428-2959. United States18.3 ProcedureMeasure the length of the specimen to thenearest 0.5 mm or164 in. Size permitting, make four measure-ments at points 90 apart around the circumference of thespecimen.8.4 ReportReport the average of the measurements as thelength of the rod
16、 or tube.9. Diameter of Rods or Outside Diameter of Tubes 300mm (12 in.) and Under in Outside Diameter9.1 ApparatusAmachinists micrometer or vernier caliperreading to 0.02 mm or 0.001 in.9.2 Test SpecimensSpecimens shall consist of tubes 300mm (12 in.) and under in outside diameter or rods of anydia
17、meter.9.3 ProcedureMeasure the outside diameter of the speci-men to the nearest 0.02 mm or 0.001 in. Make four measure-ments at points 45 apart around the circumference at each endand at the middle of the specimen.9.4 ReportReport the average of the twelve measurementsas the outside diameter of the
18、tube or the diameter of the rod.9.4.1 In the case of tubes, report the variation in outsidediameter as the difference between the maximum and mini-mum individual outside diameter readings, together with allmeasurements made.NOTE 1Rods having a diameter greater than 300 mm are generallycommercially a
19、vailable and no standard test procedures have beendeveloped for measuring dimensions of such rods.10. Outside Diameter of Tubes Over 300 mm (12 in.) inOutside Diameter10.1 ApparatusA flat steel tape graduated in steps of 0.5mm or164 in.10.2 Test SpecimenSpecimens shall consist of tubes over300 mm (1
20、2 in.) in outside diameter.10.3 ProcedurePlace the steel tape tightly around theoutside of the tube at a right angle to the long axis, and measurethe circumference to the nearest 0.5 mm or164 in. Calculate theoutside diameter by the following equation:D 5 tape reading/! 2 2t (1)where:D = average out
21、side diameter of tube, mm or in., andt = thickness of tape, mm or in.Make at least three measurements at three different locationson the tube.10.4 ReportReport the average of all measurements as theoutside diameter of the tube.11. Inside Diameter of Tubes 300 mm (12 in.) and Underin Inside Diameter1
22、1.1 ApparatusThe preferred option is to use a machin-ists inside micrometer or a vernier caliper of suitable sizereading to 0.02 mm or 0.001 in. However, the use of acombination of a telescoping gage and a standard machinistsoutside micrometer is also acceptable (see 1.2).11.2 Test SpecimenSpecimen
23、shall consist of tubes whoseinside diameter is not over 300 mm (12 in.) nor under 3 mm (18in.).11.3 ProcedureMeasure the inside diameter of the speci-men to the nearest 0.02 mm or 0.001 in. Make four measure-ments at points 45 apart around the circumference at each endof the specimen.11.4 ReportRepo
24、rt the average of the measurements takenas the inside diameter of the tube.12. Inside Diameter of Tubes Over 300 mm (12 in.) inInside Diameter12.1 ProcedureDetermine the average inside diameter bysubtracting twice the average wall thickness from the averageoutside diameter. Determine the average wal
25、l thickness froman average of at least six measurements in accordance withSection 13.13. Wall Thickness of Tubes13.1 ApparatusA ball foot micrometer or suitable verniercaliper reading to 0.02 mm or 0.001 in. shall be used for themeasurement of tubes 8 mm (516 in.) and over in insidediameter. A dial
26、micrometer reading to 0.02 mm or 0.001 in.shall be used for the measurement of tubes under 8 mm (516in.) in inside diameter.13.2 Test SpecimensSpecimens shall consist of tubes ofany length or diameter.13.3 ProcedureMeasure the wall thickness to the nearest0.02 mm or 0.001 in. For tubes 8 mm (516 in.
27、) and over ininside diameter, take four measurements at points 90 apartaround the circumference at each end of the specimen. Fortubes under 8 mm (516 in.) in inside diameter, measure the wallthickness by placing the specimen over a mandrel of slightlysmaller diameter which is fixed in position at ri
28、ght anglesrelative to the spindle of the dial micrometer. Note a zerosetting with the spindle against the pin. Then place thespecimen over the pin and take readings at various pointsaround the circumference of the specimen. Take at least fourreadings.13.4 ReportReport the average of the measurements
29、 takenas the wall thickness of the tube.14. Variation in Wall Thickness of Tubes14.1 Apparatussee 13.1.14.2 Test SpecimensSpecimens shall consist of tubes ofany length or diameter.14.3 ProcedureMeasure the wall thickness to the nearest0.02 mm or 0.001 in. For tubes 8 mm (516 in.) and over ininside d
30、iameter, make a series of measurements around eachend of the specimen. For tubes under 8 mm (516 in.) in insidediameter, measure the variation in wall thickness by rotatingthe specimen around the mandrel and following the generalprocedure in accordance with 13.3 for tubes of this size.14.4 ReportRep
31、ort the difference between the maximumand minimum values as the variation in wall thickness. Also,report all measurements taken.D668 12215. Warp15.1 ApparatusA horizontal flat surface and a rigid barwith plane surface firmly fixed at right angles to the flatsurface, both being at least as long as th
32、e specimen. The heightof the bar shall exceed half the diameter of the tube. Feelergages of suitable thicknesses will also be required.15.2 Test SpecimensSpecimens shall consist of rods ortubes of any length or diameter.15.3 ProcedurePlace the specimen in the fixture. With theaid of feeler gages, me
33、asure the maximum distance betweenthe rod or tube and the plane surface, rotating the specimen asnecessary to locate the maximum. Measure to the nearest 0.02mm or 0.001 in.15.4 ReportReport warp or lack of straightness as themaximum distance measured in accordance with 15.3.15.5 CalculationCalculate
34、 the percentage warp based on a1-m or 36-in. length as follows:Wm5 1D/L2! 3100 or W365 36D/L2! 3100 (2)where:Wm= percentage warp calculated to a 1-m length,D = maximum deviation of the rod or tube from thestraight edge, m or in.,L = actual length of the rod or tube as determined inaccordance with th
35、e procedure described in Section 7or 8, m or in., andW36= percentage warp calculated in a 36-in. length.When it is desired to compare the actual deviation for anylength with the permissible deviation for that length, use one ofthe following equations:Dxm/Dm5 Lxm2/1!2or Dx/D365 Lx2/36!2(3)where:Dxm=
36、permissible deviation from the straight edge for thegiven length, m,Dm= permissible deviation for a 1-m length,Lxm= given length, m,Dx= permissible deviation from the straight edge for thegiven length, in.,D36= permissible deviation for a 36-in. length, andLx= given length, in.NOTE 2These requiremen
37、ts do not apply to cut pieces but only to rodor tube lengths as manufactured, unless otherwise agreed upon betweenthe manufacturer and the purchaser.16. Precision and Bias16.1 These tests have been in use for many years, but noinformation has been presented to ASTM upon which to basea statement of p
38、recision. No activity has been planned todevelop such information.16.2 These test methods have no bias because the values forthese measurements are determined solely in terms of these testmethods themselves.17. Keywords17.1 dimensions; rigid rods; rigid tubes; wall thickness;warpSUMMARY OF CHANGESCo
39、mmittee D09 has identified the location of selected changes to this specification since the last issue,D668 99R04, that may impact the use of this specification. (Approved November 1, 2012.)(1) Non-mandatory terms have been eliminated.ASTM International takes no position respecting the validity of a
40、ny 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.This standard is subject to re
41、vision 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. You
42、r 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 shown below.This standard is copy
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