ASTM D6425-05(2010)e1
(Test Method)Standard Test Method for Measuring Friction and Wear Properties of Extreme Pressure (EP) Lubricating Oils Using SRV Test Machine
Standard Test Method for Measuring Friction and Wear Properties of Extreme Pressure (EP) Lubricating Oils Using SRV Test Machine
SIGNIFICANCE AND USE
This test method can be used to determine anti-wear properties and coefficient of friction of EP lubricating oils at selected temperatures and loads specified for use in applications in which high-speed vibrational or start-stop motions are present for extended periods of time under initial high Hertzian point contact pressures. It has found application as a screening test for lubricants used in gear or cam/follower systems. Users of this test method should determine whether results correlate with field performance or other applications.
SCOPE
1.1 This test method covers an extreme pressure (EP) lubricating oil's coefficient of friction and its ability to protect against wear when subjected to high-frequency, linear oscillation motion. The procedure is identical to that described in DIN 51834.
1.2 This test method can also be used to determine the ability of a non-EP lubricating oil to protect against wear and its coefficient of friction under similar test conditions.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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:D6425–05 (Reapproved 2010)
Standard Test Method for
Measuring Friction and Wear Properties of Extreme
Pressure (EP) Lubricating Oils Using SRV Test Machine
This standard is issued under the fixed designation D6425; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
´ NOTE—Updated Note 11 editorially in May 2010.
INTRODUCTION
This test method represents the transformation of DIN 51834-2:1997. The DIN working group
implemented changes at its annual meeting in Munich in September 2000. ASTM Committee D02
adopted these modifications as closely as possible. The DIN working group widens the scope of the
standard to accommodate different test conditions and refines repeatability and reproducibility on the
base of four international RR tests. It also introduces the wear volume as a tribological quantity.
1. Scope D4175 Terminology Relating to Petroleum, Petroleum
Products, and Lubricants
1.1 This test method covers an extreme pressure (EP)
E45 Test Methods for Determining the Inclusion Content of
lubricating oil’s coefficient of friction and its ability to protect
Steel
against wear when subjected to high-frequency, linear oscilla-
G40 Terminology Relating to Wear and Erosion
tion motion. The procedure is identical to that described in
2.2 DIN Standards:
DIN 51834.
DIN EN ISO 683-17 Heat-treated Steels, alloy steels and
1.2 This test method can also be used to determine the
free-cutting steels – Part 17 : Ball and roller bearing steels
ability of a non-EP lubricating oil to protect against wear and
DIN 51631:1999 Mineral spirits; special boiling point spir-
its coefficient of friction under similar test conditions.
its; requirements
1.3 The values stated in SI units are to be regarded as
DIN 51834 Tribological Test in the Translatory Oscillation
standard. No other units of measurement are included in this
Apparatus (Part 2: Determination of Friction and Wear
standard.
Data for Lubricating Oils)
1.4 This standard does not purport to address all of the
DIN EN ISO 13565-2:1998 Geometrical Product Specifica-
safety concerns, if any, associated with its use. It is the
tions (GPS)—Surface Texture: Profile Method; Surfaces
responsibility of the user of this standard to establish appro-
having Stratified Functional Properties—Part 2: Height
priate safety and health practices and determine the applica-
Characterization using Linear Material Ratio Curve (re-
bility of regulatory limitations prior to use.
placement of DIN 4776:1990)
2. Referenced Documents
2.3 ISO Standards:
ISO 1250:1972 Mineral Solvents for Paints, White Spirits
2.1 ASTM Standards:
and Related Hydrocarbon Solvents
A295 Specification for High-Carbon Anti-Friction Bearing
Steel
3. Terminology
3.1 Definitions:
3.1.1 break-in, n—in tribology, an initial transition process
This test method is under the jurisdiction of ASTM Committee D02 on
occurring in newly established wearing contacts, often accom-
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
panied by transients in coefficient of friction or wear rate, or
D02.L0.11 on Tribiological Properties of Industrial Fluids and Lubricates.
Current edition approved May 1, 2010. Published May 2010. Originally
approved in 1999. Last previous edition approved in 2005 as D6425 – 05. DOI:
10.1520/D6425-05R10E01. Available from Deutsches Institut für Normung, Beuth Verlag GmbH, Burg-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or grafenstrasse 6, D-10787 Berlin, Germany.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Available from International Organization for Standardization (ISO), 1, ch. de
Standards volume information, refer to the standard’s Document Summary page on la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
the ASTM website. www.iso.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D6425–05 (2010)
both, that are uncharacteristic of the given tribological sys-
tem’s long term behavior. (Synonym: run-in, wear-in) G40
3.1.2 C.L.A., n—in measuring surface finish, the arithmetic
average of the absolute distances of all profile points from the
mean line for a given distance.
3.1.3 coeffıcient of friction µ or f, n—in tribology, the
dimensionless ratio of the friction force (F) between two
f
bodies to the normal force (F ) pressing these bodies together.
n
G40
µ 5 ~F / F ! (1)
f n
3.1.4 EP lubricating oil, n—a liquid lubricant containing an
extreme pressure (EP) additive
3.1.5 extreme pressure (EP) additive, n—in a lubricant,a
FIG. 1 SRV Test Machine
substance that minimizes damage to metal surfaces in contact
under high stress rubbing conditions. D4175
3.1.6 Hertzian contact area, n—the apparent area of contact
4. Summary of Test Method
between two nonconforming solid bodies pressed against each
4.1 This test method is performed on an SRV test machine
other, as calculated from Hertz’ equations of elastic deforma-
using a test ball oscillated at constant frequency and stroke
tion. G40
amplitude and under constant load (F ), against a test disk that
n
3.1.7 Hertzian contact pressure, n—the magnitude of the
has been moistened with the lubricant specimen. The platform
pressure at any specified location in a Hertzian contact area, as
to which the test disk is attached is held at a constant
calculated from Hertz’ equations of elastic deformation. G40
temperature.
3.1.8 lubricant, n—any substance interposed between two
NOTE 1—The frequency of oscillation, stroke length, test temperature,
surfaces for the purpose of reducing the friction or wear
test load, test duration, and test ball and disk material can be varied from
between them. G40
those specified in this test method. The test ball yields Hertzian point
3.1.9 P , n—geometric contact pressure describes the
geom.
contact geometry. To obtain line or area contact, test pieces of differing
load carrying capacity at test end.
configurations can be substituted for the test ball.
3.1.10 RpK, n—Reduced peak height according to DIN EN
4.2 The friction force, F, is measured by a piezo-electric
f
ISO 13565-2:1998. RpK is the mean height of the peak
device in the test disk assembly. Peak values of coefficient of
sticking out above the core profile section.
friction, f, are determined and recorded as a function of time.
3.1.11 RvK, n—Reduced valley height occording to DIN
4.3 After a preset test period, the test machine and chart
EN ISO 13565-2:1998. RvK is the mean depth of the valley
recorder are stopped and the wear scar on the ball is measured.
reaching into the material below the core profile section.
Ifaprofilometerisavailable,atraceofthewearscaronthetest
3.1.12 Ry, n—in measuring surface finish, the vertical
disk can also be used to obtain additional wear information.
distance between the top of the highest peak and the bottom of
the deepest valley in one sampling length of the roughness
5. Significance and Use
profile.
5.1 This test method can be used to determine anti-wear
3.1.13 Rz, n—in measuring surface finish, the average of all
5 properties and coefficient of friction of EP lubricating oils at
Ry values (peak to valley heights) in the assessment length.
selected temperatures and loads specified for use in applica-
3.1.14 wear, n—damage to a solid surface, generally in-
tions in which high-speed vibrational or start-stop motions are
volving progressive loss of material, due to relative motion
presentforextendedperiodsoftimeunderinitialhighHertzian
between that surface and a contacting substance or substances.
point contact pressures. It has found application as a screening
G40
test for lubricants used in gear or cam/follower systems. Users
3.1.15 Wv, n—Wearvolumeisthelossofvolumetotheball
of this test method should determine whether results correlate
after a test.
with field performance or other applications.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 seizure, n—stopping of the relative motion as the
6. Apparatus
result of interfacial friction. Discussion: the seizure criteria are
6.1 SRV Test Machine (see Fig. 1), consists of an oscilla-
the stoppage of the machine, a sharp increase of the coefficient
tion drive, a test chamber (see Fig. 2), and a loading device
of friction of >+0.2 for over 20 seconds or a coefficient of
with a servomotor and a load cell. The machine is operated by
friction >0.35. If any of these conditions occur the test is not
valid. (These criteria were believed to be right, because this
standard is related to liquid lubricants).
The sole source of supply known to the committee at this time is Optimol
Instruments Prüftechnik GmbH, Friedenstrasse 10, D81671 Munich, Germany. If
you are aware of alternative suppliers, please provide this information to ASTM
Amstutz, Hu, “Surface Texture: The Parameters,”Bulletin MI-TP-003-0785, Headquarters.Your comments will receive careful consideration at a meeting of the
Sheffield Measurement Division, Warner and Swazey, 1985, p. 21. responsible technical committee, which you may attend.
6 8
ASM Handbook, “Friction, Lubrication, and Wear Technology,” Vol 18, OptimolInstrumentssuppliesanupgradekittoallowoldermachinestooperate
October 1992. with 1600 N, if needed.
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D6425–05 (2010)
< Rpk < 0.035 µm and 0.050 µm < Rvk < 0.075 µm, 24 6
0.5-mm diameter by 7.8 6 0.1-mm thick.
NOTE 2—DIN 17230-1980 was replaced by DIN EN ISO 683-17.
7.3 Cleaning Solvent, single boiling point spirit type 2-A
accordingtoDIN51631orISO1250.(Warning—Flammable.
Health hazard.)
8. Preparation of Apparatus
8.1 Turnonthetestmachineandchartrecorderandallowto
warm up for 15 min prior to running tests.
8.2 Select the friction data to be presented in the crest peak
FIG. 2 Test Chamber
value position in accordance with the manufacturer’s direc-
tions.
acontroldevicefortheoscillatingdrive,atimer,aloadcontrol,
NOTE 3—In most cases, this is accomplished by positioning the sliding
a frequency control, a stroke control, a data amplifier to
switch on electronic card No. 291.35.20E (front side of electronics behind
determine the friction coefficient, and a switch and a controller
frontpanel)andtheslidingswitchlocatedonthebackpanelofthecontrol
for the heating. An oscilloscope may be used for monitoring.
unit.
Friction coefficients are recorded in relation to time by a chart
8.3 Turn the amplitude knob to ZERO.
recorder, or by data acquisition in a computer.
8.4 Switch the stroke adjustment to AUTO position.
6.1.1 On the firmly mounted receiving block (1) in the test
8.5 Set the frequency to 50 Hz and duration to 2 h, 00 min,
chamber (see Fig. 3), there is a piezoelectric device (2) to
30 s in accordance with the manufacturer’s instructions.
measure the friction force, F, and the friction coefficient, f; the
f
8.6 Set the load charge amplifier to the setting that corre-
holder for the test disk (3) with a thermostat-controlled
sponds to the load foreseen for the test in accordance with the
electrical resistance heating element (4); a resistance thermom-
manufacturer’s instructions. The test can be run at constant
eter (5); the oscillation drive rods (6); an exchangeable holder
normal forces selected in +100 N increments starting at
for the test ball (7); and the load rods of the loading device (8).
+100 N.
6.1.2 The design of the receiving block for the test disk
NOTE 4—In later SRV models, the load charge amplifier is set auto-
should be such that it has integrated cooling coils, or that
matically.
cooling coils are wound round it, so that the receiving block
must be capable to maintaining test temperatures down to
8.7 Set the desired span, and calibrate the chart recorder in
+233K. The test disk (9) and the test ball (10) are inserted into
accordance with the manufacturer’s instructions. Select the
their respective holders (3, 4) (see Fig. 3).
desired chart speed.
6.1.3 Disks are generally used as the lower test piece. Balls,
9. Procedure
cylinders, rings, or specialized shapes may be used, with
appropriate holders, as the upper test piece (see Fig. 4).
9.1 Installation of the Test Pieces and Lubricating Oil
6.2 Microscope, equipped with a filar eyepiece graduated in
Specimen in the Test Chamber:
0.005-mm divisions or equipped with a micrometre stage
9.1.1 Using solvent resistant gloves, clean the test ball, ball
readable to 0.005 mm. Magnification should be sufficient to
holder, and disk by wiping the surfaces with laboratory tissue
allow for ease of measurement.
soaked with cleaning solvent (single boiling point spirit type
6.3 Syringe, suitable for applying 0.3 mL of the lubricating
2-A according to DIN 51631). (Warning—This mixture is
oil under test.
flammable and a health hazard.) Repeat wiping until no dark
6.4 Tweezers, straight, round, about 200-mm long, with
residue appears on the tissue. Immerse the ball and disk in a
non-marring tips.
beaker of the cleaning solvent under ultrasonic vibration (if
6.5 Torque Wrench, initial torque 0.5 to 5 Nm.
available) for 10 min. Dry the ball holder. Dry the test ball and
6.6 Ultrasonic Cleaner.
disk with a clean tissue, ensuring that no streaking occurs on
the surface.
7. Reagents and Materials
9.1.2 Ensure that the machine is unloaded (indicated by a
7.1 Test Balls, AISI 52100 Steel, 60 6 2 HRC hardness, loadreadingof–13or–14N),andinstalltheballholder(upper
0.025 6 0.005-µm C.L.A. surface finish, 10-mm diameter. specimen holder).
7.2 Test Disk, vacuum arc remelted (VAR) AISI 52100 9.1.3 Place 0.3 mL of the lubricating oil to be tested on the
steel with an inclusion rating using method D, Type A, as cleaneddisk.Theninstallthedisk(placeontheblock).Tighten
severity level number of 0,5 according to Test Methods E45 the fastening screw until resistance just begins.
and Specification A295 or a inclusion sum value K1 # 10 9.1.4 Place the cleaned ball, using the tweezers, in the
according to DIN EN ISO 683-17 and spherodized annealed to disassembled, cleaned, and dried ball holder. Tighten the
obtain globular carbide, 62 6 1 HRC hardness, the surfaces of fastening screw until resistance just begins.
the disk being lapped and free of lapping raw materials. The 9.1.5 Installtheballholder,andtestballinthetestchamber.
topography of the disk will be determined by four values: 0.5 9.1.6 Turn on the heater control, and preheat the disk holder
µm < Rz < 0.650 µm; 0.035µm < C.L.A.< 0.050 µm, 0.020 µm to 50°C.
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D6425–05 (2010)
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