1、Designation: D 3702 94 (Reapproved 2004)An American National StandardStandard 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 D 3702; the number immediately f
2、ollowing the designation indicates 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test me
3、thod covers the determination of 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 re
4、garded as the standard.In cases 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 use
5、r of this standard to establish 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 thenor
6、mal force (N) pressing these bodies 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 betweentha
7、t surface and a contacting substance 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 Spec
8、ific to This Standard:2.2.1 torquereaction 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 wit
9、h a test specimenrotating under 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
10、in.2). The meanrubbing velocity is related to spindle rotational speed: 1rpm = 0.0848 m/min (0.278 ft/min).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.
11、Significance and Use4.1 This test 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(pressure 3 velocity) limit of the test material
12、. The user of thistest method should determine to his own satisfaction whetherthe results of this test procedure correlate with field perfor-mance or other bench test machines. If the test conditions arechanged, the wear rates may change and the relative value ofone material with respect to another
13、may also change.4.2 Test conditions 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 r
14、ate precision1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.L0.05 on Solid Lubricants.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1978. Last previous e
15、dition approved in 1999 as D 3702 94 (1999).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 alternativ
16、e suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee1, which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29
17、59, United States.requires the selection of a test duration sufficient to produce 0.1mm (0.004 in.) of wear. Test durations will often be in the 50to 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 R
18、otating 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, n
19、onchlorinated.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 asrecommend
20、ed by 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 fro
21、m the 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 cottonglove
22、s or 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 t
23、o convert the specified velocity torevolutions per minute.7.5 Install the test specimen in the upper specimen holderwith the bolt and washer provided. Torque the bolt to2.8 6 0.6 J (25 6 5 in.lbf).7.6 Place the steel washer in the lower specimen holder.7.7 Balance the load lever arm with the bale ro
24、d attached.7.8 Mount the test specimen together with its specimenholder in the rotary spindle so that the drive pins of the spindleTABLE 1 Test ConditionsARotationalspeed, rpmRubbing Velocity,ft/min (m/min)Load, lb (kg), to Obtain PV, psi 3 ft/min (kg/cm23 m/min) at Selected SpeedsPV11250 (26.8) PV2
25、2500 (53.6) PV35000 (107.1) PV410 000 (214.3)36 10 (3.05) 25.0 (11.3) 50.0 (22.7) 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 3 105in./h (2.5 3 107m/h) is consider
26、ed excessive. Typical wear rates for some commonly used materials atdifferent PV levels are:Acetal homopolymer at PV1:53 106to 1 3 105in./h (1.3 3 107to 2.5 3 107m/h)Acetal homopolymer at PV2:13 105to 3 3 105in./h (2.5 3 107to 7.5 3 107m/h)22 % PTFE-filled acetal homopolymer at PV2:33 106to 6 3 106i
27、n./h (7.5 3 108to 1.5 3 107m/h)Polyamide (Type 6-6) at PV23 105to 5 3 105in./h (2.5 3 107to 1.3 3 106m/h)15 % graphite filled polyimide restin at PV3:13 105to 2 3 105in./h (2.5 3 107to 5 3 107m/h)FIG. 1 The Falex Multispecimen Test MachineD 3702 94 (2004)2are inserted in the drive pin holes of the s
28、pecimen 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(2)where F = normal force.7.10 If coefficient of friction is to be determined, checkcalibration of torque meter and adjust, if required, according t
29、oequipment manufacturers instructions.NOTE 5Calibrate torque meter such that the anticipated test torque isapproximately two-thirds of calibration value.FIG. 2 Thrust Washer Test Specimen ArrangementFIG. 3 Rotating Test SpecimenD 3702 94 (2004)3NOTE 6A chart recorder can be used to continuously reco
30、rd torquethroughout the test. Zero and span the recorder according to 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 b
31、een completed, stop the machine, remove the weightsfrom the bale rod 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
32、 prior to measuring thickness.8.6 Measure the thickness of the test 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 a
33、ttached.8.8 Mount the test specimen together with its specimenholder 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, gentlya
34、pply the appropriate weight to the bale rod.8.10 Turn on the machine 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
35、 position.8.12 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 pl
36、aces, 90 apart,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 5X1a1 X1b1 X1c1 X1d! 2 X2a1 X2b1 X2c1 X2d!4T(3)where:WR = wear rate, in./h (
37、m/h),X = thickness, in., (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.FIG. 4 Stationary Steel Washer SpecimenD 3702
38、 94 (2004)49.2 Coeffcient of Friction:9.2.1 Calculate the coefficient of friction from the torquevalues as follows:f 5 T/rW (4)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 Pre
39、cisionThe precision3of this test method for wearas determined by the statistical 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
40、 test materialwould, in the long run, in the normal and correct operation ofthe test method exceed the following values only in one case intwenty.0.019 mm 0.00075 in.! (5)10.1.2 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing in differ
41、ent laboratories on identical test material would, inthe long run, exceed the following values only in one case intwenty.0.030 mm 0.00118 in.! (6)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 robi
42、n 2b. Test durationswere 100 h, except for round robin 1 where they ranged from118 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 f
43、or measur-ing wear rate, bias has not been determined.11. Keywords11.1 coefficient 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 ar
44、m to load the stationary (lower) washeraxially upward against a rotating (upper) 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 spind
45、le is driven by a variable-speed dcmotor with feed back speed control, controlled 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 m
46、otor running time should be included.A1.3 In rotation at motion, torque is indicated 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; anddevi
47、ces to accommodate alternative test sample configurations.ASTM 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 expressly advised that determination of the validity of any such pate
48、nt 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 revised, either reapproved or withdrawn. Your comments are invited eith
49、er 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 copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United S
