ASTM D3702-94(2009)
(Test Method)Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine
Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine
SIGNIFICANCE AND USE
This test method is used to determine the equilibrium rate of wear and coefficient of friction of materials in rubbing contact under useful operating conditions, that is, combinations of pressure and velocity that fall below the PV (pressure × velocity) limit of the test material. The user of this test method should determine to his own satisfaction whether the results of this test procedure correlate with field performance or other bench test machines. If the test conditions are changed, the wear rates may change and the relative value of one material with respect to another may also change.
Test conditions may be selected from Table 1.
The precision of wear measurement is relatively independent of test duration or amount of wear, but the precision of wear rate (calculation) improves with test duration and amount of wear. It is generally believed that useful wear rate precision requires the selection of a test duration sufficient to produce 0.1 mm (0.004 in.) of wear. Test durations will often be in the 50 to 4000-h range.
TABLE 1 Test ConditionsA Rotational
speed, rpmRubbing Velocity,
ft/min (m/min)Load, lb (kg), to Obtain PV, psi × ft/min (kg/cm 2 × m/min) at Selected Speeds PV1 1250 (26.8)PV2 2500 (53.6)PV3 5000 (107.1)PV4 10 000 (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)
A For many applications a wear rate exceeding 1.0 × 10− 5 in./h (2.5 × 10−7 m/h) is considered excessive. Typical wear rates for some commonly used materials at different PV levels are: Acetal homopolymer at PV1: 5 × 10−6 to 1 × 10 −5 in./h (1.3 × 10−7 to 2.5 × 10− 7 m/h) Acetal homopolymer at PV2: 1 × 10−5 to 3 × 10 −5 in./h (2.5 × 10−7 to 7.5 × 10− 7 m/h) 22 % PTFE-filled acetal homopolymer at PV2:3 × 10− 6 to 6 × 10−6 in./h (7.5 × 10−8 to 1.5 × 10 −7 m/h) Polyamide (Type 6-6) at PV2: 1 × 10−5 to 5 × 10 −5 in./h (2.5 × 10−7 to 1.3 × 10− 6 m...
SCOPE
1.1 This test method covers the determination of wear rate and coefficient of friction for self-lubricated materials in rubbing contact by a testing machine that utilizes a thrust washer specimen configuration.
Note 1—This machine may also be used to measure coefficient of friction.
1.2 The values in SI units are to be regarded as the standard. In cases where materials, products, or equipment are available only in inch-pound units, SI values in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: D3702 − 94(Reapproved 2009)
Standard Test Method for
Wear Rate and Coefficient of Friction of Materials in Self-
Lubricated Rubbing Contact Using a Thrust Washer Testing
Machine
This standard is issued under the fixed designation D3702; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.3 wear rate—the rate of material removal or dimen-
sional change due to wear per unit of exposure parameter; for
1.1 This test method covers the determination of wear rate
example, quantity of material removed (mass, volume, thick-
and coefficient of friction for self-lubricated materials in
2 ness) in unit distance of sliding or unit time.
rubbing contact by a testing machine that utilizes a thrust
washer specimen configuration. 2.2 Definitions of Terms Specific to This Standard:
2.2.1 torque—reaction of a tendency to turn due to friction
NOTE 1—This machine may also be used to measure coefficient of
forces between specimens traveling in a circular path. It is the
friction.
product of a restraining force and the radius at which it acts to
1.2 ThevaluesinSIunitsaretoberegardedasthestandard.
balance the frictional torque.
In cases where materials, products, or equipment are available
only in inch-pound units, SI values in parentheses are for
3. Summary of Test Method
information only.
3.1 The test machine is operated with a test specimen
1.3 This standard does not purport to address all of the
rotating under load against a stationary steel washer. Each test
safety concerns, if any, associated with its use. It is the
consists of break-in for 40 h followed by a selected test
responsibility of the user of this standard to establish appro-
duration, each at the same selected normal load and speed.
priate safety and health practices and determine the applica-
Load is obtained by application of dead weights to the 10:1
2 2
bility of regulatory limitations prior to use.
lever arm. The contact area is 1.29 cm (0.20 in. ). The mean
rubbing velocity is related to spindle rotational speed: 1
2. Terminology
rpm=0.0848 m/min (0.278 ft/min).
2.1 Definitions:
3.2 The thickness change of the test specimen and torque
2.1.1 coeffıcient of friction, µ or f—in tribology—thedimen-
during test are measured for each test.
sionlessratioofthefrictionforce(F)betweentwobodiestothe
3.3 Wear rate in centimetres per hour (inches per hour) and
normal force (N) pressing these bodies together.
coefficient of friction is reported.
µ or f 5 F/N (1)
~ !
4. Significance and Use
2.1.1.1 Discussion—A distinction is often made between
static coefficient of friction and kinetic coefficient of friction.
4.1 This test method is used to determine the equilibrium
rate of wear and coefficient of friction of materials in rubbing
2.1.2 wear—damage to a solid surface, generally involving
contactunderusefuloperatingconditions,thatis,combinations
progressive loss of material, due to relative motion between
of pressure and velocity that fall below the PV (pres-
that surface and a contacting substance or substances.
sure×velocity) limit of the test material. The user of this test
method should determine to his own satisfaction whether the
resultsofthistestprocedurecorrelatewithfieldperformanceor
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
other bench test machines. If the test conditions are changed,
D02.L0.05 on Solid Lubricants.
the wear rates may change and the relative value of one
Current edition approved Oct. 1, 2009. Published November 2009. Originally
material with respect to another may also change.
approved in 1978. Last previous edition approved in 2004 as D3702–94(2004).
DOI: 10.1520/D3702-94R09.
4.2 Test conditions may be selected from Table 1.
An example known to the committee at this time is the Falex Multispecimen
Test Machine, available from Falex Corp., 1020 Airpark Drive, Sugar Grove, IL
4.3 The precision of wear measurement is relatively inde-
60554. This manufacturer recommends a maximum test load of 808 lb (367 kg). If
pendentoftestdurationoramountofwear,buttheprecisionof
you are aware of alternative suppliers, please provide this information to ASTM
wear rate (calculation) improves with test duration and amount
International Headquarters. Your comments will receive careful consideration at a
meeting of the responsible technical committee, which you may attend. of wear. It is generally believed that useful wear rate precision
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3702 − 94 (2009)
A
TABLE 1 Test Conditions
Rotational Rubbing Velocity, Load, lb (kg), to Obtain PV, psi × ft/min (kg/cm × m/min) at Selected Speeds
speed, rpm ft/min (m/min) PV 1250 (26.8) PV 2500 (53.6) PV 5000 (107.1) PV 10 000 (214.3)
1 2 3 4
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)
A −5 −7
For many applications a wear rate exceeding 1.0 × 10 in./h (2.5 × 10 m/h) is considered excessive. Typical wear rates for some commonly used materials at
different PV levels are:
−6 −5 −7 −7
Acetal homopolymer at PV : 5×10 to 1×10 in./h (1.3 × 10 to 2.5×10 m/h)
−5 −5 −7 −7
Acetal homopolymer at PV : 1×10 to 3×10 in./h (2.5 × 10 to 7.5×10 m/h)
−6 −6 −8 −7
22 % PTFE-filled acetal homopolymer at PV : 3×10 to 6×10 in./h (7.5 × 10 to 1.5×10 m/h)
−5 −5 −7 −6
Polyamide (Type 6-6) at PV : 1×10 to 5×10 in./h (2.5 × 10 to 1.3×10 m/h)
−5 −5 −7 −7
15 % graphite filled polyimide restin at PV : 1×10 to 2×10 in./h (2.5 × 10 to 5×10 m/h)
requirestheselectionofatestdurationsufficienttoproduce0.1 7. Preparation of Apparatus
mm (0.004 in.) of wear. Test durations will often be in the 50
7.1 Measure the finish of the steel mating surface perpen-
to 4000-h range.
dicular to the finishing direction.
7.2 Before each test, thoroughly clean the steel washer and
5. Apparatus
both specimen holders using the solvent per 5.1.
5.1 Falex Multispecimen Test Machine, Fig. 1, shown sche-
matically in Fig. 2 and described in Annex A1.
NOTE 3—Remove all solvents from the washer before testing.
7.3 Clean the test specimen as recommended by the manu-
5.2 Test Specimen or Rotating Wafer, shown in Fig. 3.
facturer of the test material.
5.3 Stationary Washer, AISI C-1018 steel, shown in Fig. 4.
7.3.1 Store cleaned test specimens prior to testing in a glass
The surface finish should be 16 6 2 µin.AA, the hardness Rc
jar.
20 6 5.
7.3.2 Following the cleaning, do not handle the test speci-
5.4 Micrometer (Note 4), capable of measuring to the
mens with bare hands. It is recommended that clean cotton
nearest 0.003 mm (0.0001 in.).
gloves or clean tweezers or tongs be used.
6. Reagents and Materials NOTE 4—Check compatibility of the test specimen cleaning procedure
and reagents with the specific material to be tested.
6.1 Solvent, safe, non-film forming, nonchlorinated.
7.4 Preset the speed control to provide the desired speed as
NOTE 2—Petroleum distillates, formerly used as solvents, have been
measured in revolutions per minute using the built-in tachom-
eliminated due to possible toxic effects. Each user should select a solvent
eter. Refer to Table 1 to convert the specified velocity to
that can meet applicable safety requirements and thoroughly clean
revolutions per minute.
machine parts.
6.2 Appropriate reagents for cleaning the test specimen as 7.5 Install the test specimen in the upper specimen holder
recommended by the manufacturer of the test material. with the bolt and washer provided. Torque th
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