ASTM_D_3702_-_94_2014.pdf

Designation:D370294(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 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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of wear rateand coefficient of friction for self-lubricated materials inrubbing contact by a testing machine2that utilizes a thrustwasher specimen configuration.NOTE1This 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 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 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 bodies together.or f 5F/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 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 Specific 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 with 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 in.2).The meanrubbing velocity is related to spindle rotational speed:1 rpm=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.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(pres-sure velocity)limit of the test material.The user of this testmethod should 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 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 under 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 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 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.United States1 requires 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 S