1、Designation: E4 16 American Association StateHighway and Transportation Officials StandardsAASHTO No: T67Standard Practices forForce Verification of Testing Machines1This standard is issued under the fixed designation E4; the number immediately following the designation indicates the year of origina
2、ladoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defen
3、se.1. Scope*1.1 These practices cover procedures for the forceverification, by means of standard calibration devices, oftension or compression, or both, static or quasi-static testingmachines (which may, or may not, have force-indicatingsystems). These practices are not intended to be completepurcha
4、se specifications for testing machines. Testing machinesmay be verified by one of the three following methods orcombination thereof:1.1.1 Use of standard weights,1.1.2 Use of equal-arm balances and standard weights, or1.1.3 Use of elastic calibration devices.NOTE 1These practices do not cover the ve
5、rification of all types oftesting machines designed to measure forces, for example, the constant-rate-of-loading type which operates on the inclined-plane principle. Thistype of machine may be verified as directed in the applicable appendix ofSpecification D76/D76M.1.2 The procedures of 1.1.1 1.1.3
6、apply to the verificationof the force-indicating systems associated with the testingmachine, such as a scale, dial, marked or unmarked recorderchart, digital display, etc. In all cases the buyer/owner/usermust designate the force-indicating system(s) to be verified andincluded in the report.1.3 Unit
7、sThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in each system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with t
8、he standard.1.3.1 Other customary force units may be used with thisstandard such as the kilogram-force (kgf) which is often usedwith hardness testing machines1.4 Forces indicated on displays/printouts of testing ma-chine data systemsbe they instantaneous, delayed, stored, orretransmittedwhich are ve
9、rified with provisions of 1.1.1,1.1.2,or1.1.3, and are within the 61 % accuracy requirement,comply with Practices E4.1.5 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-priat
10、e safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D76/D76M Specification for Tensile Testing Machines forTextilesE6 Terminology Relating to Methods of Mechanical TestingE74 Practice of Calibration of Force
11、-Measuring Instrumentsfor Verifying the Force Indication of Testing MachinesE467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing System3. Terminology3.1 For definitions of terms used in this practice, refer toTerminology E6.3.2 Definitions:3.2.1 elastic ca
12、libration device, na device for use inverifying the force readings of a testing machine consisting ofan elastic member(s) to which forces may be applied, com-bined with a mechanism or device for indicating the magnitude(or a quantity proportional to the magnitude) of deformationunder force.3.2.2 por
13、table testing machine (force-measuring type), nadevice specifically designed to be moved from place to placeand for applying a force (load) to a specimen.3.2.3 testing machine (force-measuring type), na me-chanical device for applying a force to a specimen.3.3 Definitions of Terms Specific to This S
14、tandard:1These practices are under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.01 onCalibration of Mechanical Testing Machines and Apparatus.Current edition approved May 15, 2016. Published June 2016. Originallyapproved in 1923. La
15、st previous edition approved in 2015 as E4 15. DOI:10.1520/E0004-16.2For 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 w
16、ebsite.*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 States13.3.1 accuracy, nthe specified permissible variation fromthe reference value.3.3.1.1 DiscussionAtesting machine is
17、 said to be accurateif the indicated force is within the specified permissiblevariation from the actual force. In these methods the word“accurate” applied to a testing machine is used withoutnumerical values, for example, “An accurate testing machinewas used for the investigation.” The accuracy of a
18、 testingmachine should not be confused with sensitivity. For example,a testing machine might be very sensitive; that is, it mightindicate quickly and definitely small changes in force, butnevertheless, be very inaccurate. On the other hand, theaccuracy of the results is in general limited by the sen
19、sitivity.3.3.2 calibration, n in the case of force testing machines,the process of comparing the force indication of the machineunder test to that of a standard, making adjustments as neededto meet error requirements.3.3.3 capacity range, nin the case of testing machines, therange of forces for whic
20、h it is designed.3.3.3.1 DiscussionSome testing machines have more thanone capacity range, that is, multiple ranges.3.3.4 correction, nin the case of a testing machine, thedifference obtained by subtracting the indicated force from thecorrect value of the applied force.3.3.5 error (or the deviation
21、from the correct value), ninthe case of a testing machine, the difference obtained bysubtracting the force indicated by the calibration device fromthe force indicated by the testing machine.3.3.5.1 DiscussionThe word “error” shall be used withnumerical values, for example, “At a force of 300 kN 60 0
22、00lbf, the error of the testing machine was + 67 N + 15 lbf.”3.3.6 force, nin the case of testing machines, a forcemeasured in units such as pound-force, newton, or kilogram-force.3.3.6.1 DiscussionThe newton is that force which actingon a 1-kg mass will give to it an acceleration of 1 m/s2. Thepoun
23、d-force is that force which acting on a 1-lb mass willgive to it an acceleration of 9.80665 m/s232.1740 ft/s2. Thekilogram-force is that force which acting on a 1-kg mass willgive to it an acceleration of 9.80665 m/s232.1740 ft/s2.3.3.7 percent error, nin the case of a testing machine, theratio, exp
24、ressed as a percent, of the error to the correct value ofthe applied force.3.3.7.1 DiscussionThe test force, as indicated by thetesting machine, and the applied force, as computed from thereadings of the verification device, shall be recorded at eachtest point. The error, E, and the percent error, E
25、p, shall becalculated from these data as follows:E 5 A 2 B (1)Ep5 A 2 B!/B# 3100where:A = force indicated by machine being verified, N or lbf,andB = correct value of the applied force, N or lbf, asdetermined by the calibration device.3.3.8 permissible variation (or tolerance), nin the case oftesting
26、 machines, the maximum allowable error in the value ofthe quantity indicated.3.3.8.1 DiscussionIt is convenient to express permissiblevariation in terms of percentage of error. The numerical valueof the permissible variation for a testing machine is so statedhereafter in these practices.3.3.9 resolu
27、tion of the force indicator, nsmallest change offorce that can be estimated or ascertained on the forceindicating apparatus of the testing machine, at any appliedforce. Appendix X1 describes a method for determiningresolution.3.3.10 resolution of analog type force indicators (scales,dials, recorders
28、, etc.), nthe resolution is the smallest changein force indicated by a displacement of a pointer, or pen line.3.3.10.1 DiscussionThe resolution is calculated by multi-plying the force corresponding to one graduation by the ratio ofthe width of the pointer or pen line to the center to centerdistance
29、between two adjacent graduation marks. The typicalratios used are 1:1, 1:2, 1:5, or 1:10.Aspacing of 2.5 mm 0.10in. or greater is recommended for the ratio of 1:10.Aratio lessthan 1:10 should not be used.3.3.10.2 DiscussionIf a force indicating dial has gradua-tions spaced every 2.0 mm 0.080 in., th
30、e width of the pointeris approximately 1.0 mm (0.040 in.), and one graduationrepresent 25N 5 lbf. The ratio used would be 1:2 and theresolution would be equal to 12-12 N 2-12 lbf.3.3.11 resolution of digital type force indicators (numeric,displays, printouts, etc.), nthe resolution is the smallestch
31、ange in force that can be displayed on the force indicator, atany applied force.3.3.11.1 DiscussionA single digit or a combination ofdigits may be the smallest change in force that can beindicated.3.3.11.2 DiscussionIf the force indication, for either typeof force indicator, fluctuates by more than
32、twice the resolution,as described in 3.3.10 or 3.3.11, the resolution, expressed as aforce, shall be equal to one-half the range of the fluctuation.3.3.12 verification, n in the case of force testing machines,the process of comparing the force indication of the machineunder test to that of a standar
33、d and reporting results, withoutmaking adjustments.3.3.13 verified range of forces, nin the case of testingmachines, the range of indicated forces for which the testingmachine gives results within the permissible variations speci-fied.4. Significance and Use4.1 Testing machines that apply and indica
34、te force are usedin many industries, in many ways. They may be used in aresearch laboratory to measure material properties, and in aproduction line to qualify a product for shipment. No matterwhat the end use of the machine may be, it is necessary forusers to know that the amount of force applied an
35、d indicated istraceable to the International System of Units (SI) through aNational Metrology Institute (NMI). The procedures in Prac-tices E4 may be used to verify these machines so that theE4162indicated forces are traceable to the SI. A key element oftraceability to the SI is that the devices use
36、d in the verificationhave known force characteristics, and have been calibrated inaccordance with Practice E74.4.2 The procedures in Practices E4 may be used by thoseusing, manufacturing, and providing calibration service fortesting machines and related instrumentation.5. Calibration Devices5.1 When
37、 verifying testing machines, use calibration de-vices only over their Class A force ranges as determined byPractice E74.6. Advantages and Limitations of Methods6.1 Verification by Standard WeightsVerification by thedirect application of standard weights to the weighing mecha-nism of the testing mach
38、ine, where practicable, is the mostaccurate method. Its limitations are: (1) the small range offorces that can be verified, (2) the nonportability of any largeamount of standards weights, and (3) its nonapplicability tohorizontal testing machines or vertical testing machines havingweighing mechanism
39、s that are not designed to be actuated bya downward force.6.2 Verification by Equal-Arm Balance and StandardWeightsThe second method of verification of testing ma-chines involves measurement of the force by means of anequal-arm balance and standard weights. This method islimited to a still smaller r
40、ange of forces than the foregoingmethod, and is generally applicable only to certain types ofhardness testing machines in which the force is applied throughan internal lever system.6.3 Verification by Elastic Calibration DevicesThe thirdmethod of verification of testing machines involves measure-men
41、t of the elastic strain or deflection under force of a ring,loop, tension or compression bar, or other elastic device. Theelastic calibration device is free from the limitations referred toin 6.1 and 6.2.7. System Verification7.1 A testing machine shall be verified as a system with theforce sensing
42、and indicating devices (see 1.2 and 1.4) in placeand operating as in actual use.7.1.1 If this is not technically possible, refer to Annex A1,Verifying the Force Measuring System out of theTest Machine.Out of the test machine verifications shall be in accordancewith the main body of Practices E4 and
43、its Annex A17.2 System verification is invalid if the devices are removedand checked independently of the testing machine unlessverification is performed according to Annex A1.7.3 Many testing machines utilize more than one forcemeasuring device in order to obtain more accurate forceindication at lo
44、wer applied forces. These devices are routinelyinstalled and uninstalled in the testing machine. For suchdevices, interchangeability shall be established during theoriginal verification and shall be reestablished after an adjust-ment is performed. This is accomplished by performing anormal verificat
45、ion with the device in place as during normaluse. It is advisable that orientation be kept consistent, such asby noting the direction of the cable connector so that whenreinstalling the device, the orientation will be repeated. Re-move and reinstall the device between the two verification runsto dem
46、onstrate interchangeability. Repeat the procedure foreach interchangeable force measuring device used in thetesting machine.7.3.1 Introduction of the new force measuring devices shallrequire that interchangeability be established per 7.3.7.4 A Practices E4 Verification consists of at least twoverifi
47、cation runs of the forces contained in the force range(s)selected. See 10.1 and 10.3.7.4.1 If the initial verification run produces values withinthe Practices E4 requirements of Section 14, the data may beused “as found” for run one of the two required for the newverification report.7.4.2 If the ini
48、tial verification run produces any valueswhich are outside of the Practices E4 requirements, the “asfound” data may be reported and may be used in accordancewith applicable quality control programs. Calibration adjust-ments shall be made to the force indicator system(s), afterwhich the two required
49、verification runs shall be conducted andreported in the new verification report and certificate.7.4.3 Calibration adjustments may be made to improve theaccuracy of the system. They shall be followed by the tworequired verification runs, and issuance of a new verificationreport and certificate.8. Gravity and Air Buoyancy Corrections8.1 In the verification of testing machines, where standardweights are used for applying forces directly or through leveror balance-arm systems, correct the force for the local value ofgravity and
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