1、Designation: D3702 94 (Reapproved 2014)Standard Test Method forWear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer TestingMachine1This standard is issued under the fixed designation D3702; the number immediately following the designation indica
2、tes the year oforiginal adoption or, in the case of revision, the year 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. Scope1.1 This test method covers the determination of
3、 wear rateand coefficient of friction for self-lubricated materials inrubbing contact by a testing machine2that utilizes a thrustwasher specimen configuration.NOTE 1This machine may also be used to measure coefficient offriction.1.2 The values in SI units are to be regarded as the standard.In cases
4、where materials, products, or equipment are availableonly in inch-pound units, SI values in parentheses are forinformation only.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
5、appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions:2.1.1 coeffcient of friction, or fin tribologythe dimen-sionless ratio of the friction force (F) between two bodies to thenormal force (N) pressing these bod
6、ies together. or f 5 F/N! (1)2.1.1.1 DiscussionA distinction is often made betweenstatic coefficient of friction and kinetic coefficient of friction.2.1.2 weardamage to a solid surface, generally involvingprogressive loss of material, due to relative motion betweenthat surface and a contacting subst
7、ance or substances.2.1.3 wear ratethe rate of material removal or dimen-sional change due to wear per unit of exposure parameter; forexample, quantity of material removed (mass, volume, thick-ness) in unit distance of sliding or unit time.2.2 Definitions of Terms Specific to This Standard:2.2.1 torq
8、uereaction of a tendency to turn due to frictionforces between specimens traveling in a circular path. It is theproduct of a restraining force and the radius at which it acts tobalance the frictional torque.3. Summary of Test Method3.1 The test machine is operated with a test specimenrotating under
9、load against a stationary steel washer. Each testconsists of break-in for 40 h followed by a selected testduration, each at the same selected normal load and speed.Load is obtained by application of dead weights to the 10:1lever arm. The contact area is 1.29 cm2(0.20 in.2). The meanrubbing velocity
10、is related to spindle rotational speed:1 rpm = 0.0848 mmin (0.278 ftmin).3.2 The thickness change of the test specimen and torqueduring test are measured for each test.3.3 Wear rate in centimetres per hour (inches per hour) andcoefficient of friction is reported.4. Significance and Use4.1 This test
11、method is used to determine the equilibriumrate of wear and coefficient of friction of materials in rubbingcontact under useful operating conditions, that is, combinationsof pressure and velocity that fall below the PV (pres-sure velocity) limit of the test material. The user of this testmethod shou
12、ld determine to his own satisfaction whether theresults of this test procedure correlate with field performance orother bench test machines. If the test conditions are changed,the wear rates may change and the relative value of onematerial with respect to another may also change.4.2 Test conditions
13、may be selected from Table 1.4.3 The precision of wear measurement is relatively inde-pendent of test duration or amount of wear, but the precision ofwear rate (calculation) improves with test duration and amountof wear. It is generally believed that useful wear rate precision1This test method is un
14、der the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.L0.05 on Solid Lubricants.Current edition approved May 1, 2014. Published July 2014. Originally approvedin 1978. Last previous edition approved in 2009 as
15、 D3702 94 (2009). DOI:10.1520/D3702-94R14.2An example known to the committee at this time is the Falex MultispecimenTest Machine, available from Falex Corp., 1020 Airpark Drive, Sugar Grove, IL60554. This manufacturer recommends a maximum test load of 808 lb (367 kg). Ifyou are aware of alternative
16、suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.
17、United States1requires the selection of a test duration sufficient to produce0.1 mm (0.004 in.) of wear. Test durations will often be in the50 to 4000-h range.5. Apparatus5.1 Falex Multispecimen Test Machine, Fig. 1, shown sche-matically in Fig. 2 and described in Annex A1.5.2 Test Specimen or Rotat
18、ing Wafer, shown in Fig. 3.5.3 Stationary Washer, AISI C-1018 steel, shown in Fig. 4.The surface finish should be 16 6 2 in. AA, the hardness Rc20 6 5.5.4 Micrometer (Note 4), capable of measuring to thenearest 0.003 mm (0.0001 in.).6. Reagents and Materials6.1 Solvent, safe, non-film forming, nonch
19、lorinated.NOTE 2Petroleum distillates, formerly used as solvents, have beeneliminated due to possible toxic effects. Each user should select a solventthat can meet applicable safety requirements and thoroughly cleanmachine parts.6.2 Appropriate reagents for cleaning the test specimen asrecommended b
20、y the manufacturer of the test material.7. Preparation of Apparatus7.1 Measure the finish of the steel mating surface perpen-dicular to the finishing direction.7.2 Before each test, thoroughly clean the steel washer andboth specimen holders using the solvent per 5.1.NOTE 3Remove all solvents from th
21、e washer before testing.7.3 Clean the test specimen as recommended by the manu-facturer of the test material.7.3.1 Store cleaned test specimens prior to testing in a glassjar.7.3.2 Following the cleaning, do not handle the test speci-mens with bare hands. It is recommended that clean cottongloves or
22、 clean tweezers or tongs be used.NOTE 4Check compatibility of the test specimen cleaning procedureand reagents with the specific material to be tested.7.4 Preset the speed control to provide the desired speed asmeasured in revolutions per minute using the built-in tachom-eter. Refer to Table 1 to co
23、nvert the specified velocity torevolutions per minute.TABLE 1 Test ConditionsARotationalspeed, rpmRubbing Velocity,ft/min (m/min)Load, lb (kg), to Obtain PV, psi ft min (kg/cm2 m min) at Selected SpeedsPV11250 (26.8) PV22500 (53.6) PV35000 (107.1) PV410 000 (214.3)36 10 (3.05) 25.0 (11.3) 50.0 (22.7
24、) 100 (45.4) 200 (90.7)180 50 (15.2) 5.0 (2.3) 10.0 (4.5) 20.0 (9.1) 40.0 (18.1)900 250 (76.2) 1.0 (0.5) 2.0 (0.9) 4.0 (1.8) 8.0 (3.6)AFor many applications a wear rate exceeding 1.0 105in./h (2.5 107m/h) is considered excessive. Typical wear rates for some commonly used materials at differentPV lev
25、els are:Acetal homopolymer at PV1: 5106to1105in./h (1.3 107to2.5107m/h)Acetal homopolymer at PV2: 1105to3105in./h (2.5 107to7.5107m/h)22 % PTFE-filled acetal homopolymer at PV2: 3106to6106in./h (7.5 108to1.5107m/h)Polyamide (Type 6-6) at PV2: 1105to5105in./h (2.5 107to1.3106m/h)15 % graphite filled
26、polyimide restin at PV3: 1105to2105in./h (2.5 107to5107m/h)FIG. 1 The Falex Multispecimen Test MachineD3702 94 (2014)27.5 Install the test specimen in the upper specimen holderwith the bolt and washer provided. Torque the bolt to2.860.6 J 2565 in.lbf! (2)7.6 Place the steel washer in the lower speci
27、men holder.7.7 Balance the load lever arm with the bale rod attached.FIG. 2 Thrust Washer Test Specimen ArrangementFIG. 3 Rotating Test SpecimenD3702 94 (2014)37.8 Mount the test specimen together with its specimenholder in the rotary spindle so that the drive pins of the spindleare inserted in the
28、drive pin holes of the specimen holder andthe specimen holder is free to pivot on the ball seat.7.9 Determine the dead weight, w, to be applied to the balerod as follows:W 5F10(3)where:F = normal force.7.10 If coefficient of friction is to be determined, checkcalibration of torque meter and adjust,
29、if required, according toequipment manufacturers instructions.NOTE 5Calibrate torque meter such that the anticipated test torque isapproximately two-thirds of calibration value.NOTE 6A chart recorder can be used to continuously record torquethroughout the test. Zero and span the recorder according t
30、o the manu-facturers instructions.8. Procedure8.1 With the specimens and bale rod in position, gentlyapply the appropriate weight to the bale rod.8.2 Turn on the machine.8.3 When the prescribed break-in interval duration (40 h)has been completed, stop the machine, remove the weightsfrom the bale rod
31、 and carefully lower the stationary specimenholder to its lowest position.8.4 Remove the test specimen together with its specimenholder and clean with a lint-free wiper.8.5 Condition the specimens for a minimum of1hatroomtemperature prior to measuring thickness.8.6 Measure the thickness of the test
32、specimen together withits specimen holder at four places, 90 apart. Mark the testspecimen (inside the raised test surface) so subsequent mea-surements can be made at the same places.8.7 Balance the load lever arm with the bale rod attached.8.8 Mount the test specimen together with its specimenholder
33、 in the rotary spindle so that the drive pins of the spindleare inserted in the drive pin holes of the specimen holder andthe specimen holder is free to pivot on the ball seat.8.9 With the specimens and bale rod in position, gentlyapply the appropriate weight to the bale rod.8.10 Turn on the machine
34、 and chart recorder if torque is tobe recorded.8.11 When the prescribed test interval duration has beencompleted, stop the machine, remove the weights from the balerod, and carefully lower the stationary specimen holder to itslowest position.FIG. 4 Stationary Steel Washer SpecimenD3702 94 (2014)48.1
35、2 Remove the test specimen together with its specimenholder and clean with a lint-free wiper.8.13 Condition the specimens for a minimum of1hatroomtemperature prior to measuring thickness.8.14 Measure the thickness of the test specimen togetherwith its specimen holder at the same four places, 90 apar
36、t,previously marked.9. Calculation9.1 Wear:9.1.1 Record the (four) thickness measurements for the testspecimen before and after test, and actual test duration inhours.9.1.2 Calculate the wear rate as follows:WR 5X1a1X1b1X1c1X1d!2X2a1X2b1X2c1X2d!4T(4)where:WR = wear rate, in./h (m/h),X = thickness, i
37、n., (m), andT = test duration, h.9.1.3 Subscripts 1a,1b,1c, and 1d are the initial fourthickness measurements taken 90 apart on the upper rotatingspecimen. Subscripts 2a,2b,2c, and 2d are the correspondingfinal thickness measurements.9.2 Coeffcient of Friction:9.2.1 Calculate the coefficient of fric
38、tion from the torquevalues as follows:f 5 T/rW (5)where:f = coefficient of friction,T = specimen torque, Nm (lbin.),r = test specimen radius, 13.49 mm (0.531 in.), andW = normal force, kg (lb).10. Precision and Bias10.1 PrecisionThe precision3of this test method for wearas determined by the statisti
39、cal examination of interlaboratorytest results is as follows:10.1.1 RepeatabilityThe difference between successiveresults obtained by the same operator with the same apparatusunder constant operating conditions on identical test materialwould, in the long run, in the normal and correct operation oft
40、he test method exceed the following values only in one case intwenty.0.019 mm 0.00075 in.! (6)10.1.2 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, exceed the
41、 following values only in one case intwenty.0.030 mm 0.00118 in.! (7)10.2 The tests on which the precision statement is basedwere all conducted at PV3, with 180 rpm used in round robin1, 2a, and 3, and 720 rpm in round robin 2b. Test durationswere 100 h, except for round robin 1 where they ranged fr
42、om118 to 313 h. Wear in 100 h round robins averaged 0.00027 to0.00049 in., and in no test did wear exceed 0.0017 in.10.3 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure for measur-ing wear rate, bias has not been determined.11. Keywords11.1 coeffi
43、cient of friction; self-lubricated; torque; wear;wear-rateANNEX(Mandatory Information)A1. DESCRIPTION OF THE THRUST WASHER TESTING MACHINE (Fig. 1)A1.1 Dead weights are attached to a bale rod, and actthrough a 10:1 lever arm to load the stationary (lower) washeraxially upward against a rotating (upp
44、er) test specimen. Thelever arm may be balanced to compensate for the weight of thestationary washer. Optional controlled pneumatic loading sys-tems are available to replace applications of dead weight.A1.2 The rotary spindle is driven by a variable-speed dcmotor with feed back speed control, contro
45、lled by a 10-turnpotentiometer, acting through dual-range step pulleys. Typicalspindle speed range is 10 to 7200 rpm. A built-in tachometerprovides speed indication. An elapsed time indicator with resetfeature to indicate motor running time should be included.A1.3 In rotation at motion, torque is in
46、dicated throughoutthe test by a digital indicator.A1.4 Optional features include an assortment of torquemeasurement devices; apparatus for the application, control,and readout of various test environment conditions; anddevices to accommodate alternative test sample configurations.3Supporting data ha
47、ve been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1054.D3702 94 (2014)5ASTM 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 e
48、xpressly 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 revision at any time by the responsible technical committee and must be reviewed every five years andif not rev
49、ised, 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. 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 shown below.This standard is cop
