ASTM D2596-97(2008)
(Test Method)Standard Test Method for Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method)
Standard Test Method for Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method)
SIGNIFICANCE AND USE
This test method, used for specification purposes, differentiates between lubricating greases having low, medium, and high level of extreme-pressure properties. The results do not necessarily correlate with results from service.
It is noted that lubricating greases that have as their fluid component a silicone, halogenated silicone, or a mixture comprising silicone fluid and petroleum oil, are not applicable to this method of test.
SCOPE
1.1 This test method covers the determination of the load-carrying properties of lubricating greases. Two determinations are made:
1.1.1 Load-Wear Index (formerly called Mean-Hertz Load), and
1.1.2 Weld Point, by means of the Four-Ball Extreme-Pressure (EP) Tester.
1.2 The values stated in SI units are to be regarded as the standard. The 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. Specific precautionary statements are given in 7.1 and 7.2.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D2596–97 (Reapproved 2008)
Standard Test Method for
Measurement of Extreme-Pressure Properties of Lubricating
Grease (Four-Ball Method)
This standard is issued under the fixed designation D2596; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope
1.1 This test method covers the determination of the load-
carrying properties of lubricating greases. Two determinations
are made:
1.1.1 Load-Wear Index (formerly called Mean-Hertz Load),
and
1.1.2 Weld Point, by means of the Four-Ball Extreme-
Pressure (EP) Tester.
1.2 The values stated in SI units are to be regarded as the
standard. The 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Specific precau-
tionary statements are given in 7.1 and 7.2.
2. Referenced Documents
FIG. 1 Schematic Plot of Scar Diameter Versus Applied Load
2.1 ASTM Standards:
D235 Specification for Mineral Spirits (Petroleum Spirits)
3.1.2 compensationscardiameter—theaveragediameter,in
(Hydrocarbon Dry Cleaning Solvent)
millimetres, of the wear scar on the stationary balls caused by
2.2 American National Standard:
3 the rotating ball under an applied load in the presence of a
B3.12 Metal Balls
lubricant, but without causing either seizure or welding.
3. Terminology 3.1.3 corrected load, n—the load in kilograms-force (or
Newtons) obtained by multiplying the applied load by the ratio
3.1 Definitions:
of the Hertz scar diameter to the measured scar diameter at that
3.1.1 compensation line, n—a line of plot on log-log paper
load.
where the coordinates are scar diameter in millimetres and
3.1.3.1 Discussion—In this test method, the corrected load
applied load in kilograms-force (or Newtons) obtained under
is calculated for each run.
dynamic conditions.
3.1.4 hertz line, n—a line of plot on log-log paper where the
3.1.1.1 Discussion—Shown in Fig. 1 as line ABE.
coordinatesarescardiameterinmillimetresandappliedloadin
kilograms-force (or Newtons) obtained under static conditions.
This test method is under the jurisdiction of ASTM Committee D02 on
3.1.4.1 Discussion—Shown in Fig. 1 as a hertz line.
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
3.1.5 hertz scar diameter, n—the average diameter, in
D02.G0.04 on Functional Tests - Tribology.
millimetres, of an indentation caused by the deformation of the
Current edition approved May 1, 2008. Published September 2008. Originally
´1
approved in 1967. Last previous edition approved in 2002 as D2596–97(2002) .
balls under static load (prior to test). It may be calculated from
DOI: 10.1520/D2596-97R08.
the equation:
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
–2 1/3
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
D 5 8.73 3 10 P! (1)
~
h
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
where:
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
D = Hertz diameter of the contact area in millimetres, and
h
4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2596–97 (2008)
P = static applied load in kilograms-force.
3.1.6 immediate seizure region, n—that region of the scar-
load curve characterized by seizure or welding at the startup or
by large wear scars.
3.1.6.1 Discussion—Under conditions of this test method,
the immediate seizure region is shown by line CD.Also, initial
deflection of indicating pen on the optional friction-measuring
device is larger than with nonseizure loads.
3.1.7 incipient seizure or initial seizure region, n—that
region at which, with an applied load, there is a momentary
breakdown of the lubricating film.
3.1.7.1 Discussion—This breakdown is noted by a sudden
increase in the measured scar diameter, shown in Fig. 1 as line
BC, and a momentary deflection of the indicating pen of the
optional friction-measuring device.
3.1.8 last nonseizure load, n—the last load at which the
measured scar diameter is not more than 5 % greater than the
compenation value at that load.
3.1.8.1 Discussion—Shown in Fig. 1 as Point B.
FIG. 2 Sectional View of Four-Ball EP Tester
3.1.9 load-wear index (or the load-carrying property of a
lubricant), n—an index of the ability of a lubricant to prevent
5.2 Itisnotedthatlubricatinggreasesthathaveastheirfluid
wear at applied loads.
component a silicone, halogenated silicone, or a mixture
3.1.9.1 Discussion—Under the conditions of this test, spe-
comprising silicone fluid and petroleum oil, are not applicable
cific loadings in kilograms-force (or Newtons) having intervals
to this method of test.
of approximately 0.1 logarithmic units, are applied to the three
stationary balls for ten runs prior to welding. The load wear 6. Apparatus
index is the average of the corrected loads determined for the
6.1 Four-Ball Extreme-Pressure Lubricant Tester, illus-
ten applied loads immediately preceding the weld point.
trated in Fig. 2.
3.1.10 weld point, n—the lowest applied load at which
NOTE 1—It is important to distinguish between the Four-Ball EPTester
sliding surfaces seize and then weld.
and the Four-Ball Wear Tester. The Four-Ball Wear Tester can be used
3.1.10.1 Discussion—Under the conditions of this test, the
under a variety of test conditions at loads up to 490 N (50 kgf). The
lowest applied load in kilograms-force (or Newtons) at which
Four-Ball EP Tester is designed for testing under more severe conditions
the rotating ball seizes and then welds to the three stationary
and lacks the sensitivity necessary for the Four-Ball Wear Test.
balls, indicating the extreme-pressure level of the lubricating
6.2 Microscope, equipped with calibrated measuring scale
grease has been exceeded. See Fig. 1, Point D.
and readable to an accuracy of 0.01 mm.
3.1.10.2 Discussion—Some lubricating greases do not al-
6.3 Timer, graduated in tenths of a second.
low true welding, and extreme scoring of the three stationary
NOTE 2—Optional equipment with Four-Ball apparatus consists of a
balls results. In such cases, the applied load which produces a
friction-measuring device electrically driven and conveniently graduated
maximum scar diameter of 4 mm is reported as the weld point.
in 10-s markings.
4. Summary of Test Method
7. Materials
4.1 The tester is operated with one steel ball under load
7.1 Stoddard Solvent Specifications D235.(Warning—
rotating against three steel balls held stationary in the form of
Combustible. Health hazard.)
a cradle. The rotating speed is 1770 6 60 rpm. Lubricating 6
7.2 ASTM n-Heptane (Warning—Flammable. Health haz-
greases are brought to 27 6 8°C (80 6 15°F) and then
ard.)
subjectedtoaseriesoftestsof10-sdurationatincreasingloads 7
7.3 Test Balls —Testballsshallbechromealloysteel,made
until welding occurs.
from AISI standard steel No. E-52100, with diameter of 12.7
5. Significance and Use
The sole source of supply of the apparatus (microscopes 103.10 A and 103.10
5.1 This test method, used for specification purposes, dif-
B) known to the committee at this time is Falex Corporation, 1020 Airpark Dr.,
ferentiates between lubricating greases having low, medium, Sugar Grove, IL, 60554-9585. If you are aware of alternative suppliers, please
provide this information toASTM International Headquarters. Your comments will
and high level of extreme-pressure properties. The results do
receive careful consideration at a meeting of the responsible technical committee,
not necessarily correlate with results from service.
which you may attend.
Described in the 1998 Annual Book of ASTM Standards, Vol 05.04, Motor
Fuels, Section I, Annex 2, Section A2.7, Reference Materials.
Steelballsmeetingthisdescriptionwereusedindevelopingtheprecisionofthe
Further details on this test method may be found in: Sayles, F. S., et al, test. They are available from ball bearing or laboratory equipment manufacturers
National Lubricating Grease Institute Spokesman, Vol 32, No. 5,August 1968, pp. and distributors. All balls used in one test should be taken from one carton (of 500
162–167. balls) as received from the supplier.
D2596–97 (2008)
mm (0.5 in.), Grade 25 EP (Extra Polish). Such balls are 9.9 Measure the scar diameter of test balls as follows:
described in ANSI Specifications B3.12, for Metal Balls. The
9.9.1 Option A—Remove the lock nut and release the test
Extra-Polish finish is not described in that specification. The
balls.CleantheballswithStoddardsolventandthenn-heptane,
Rockwell C hardness shall be 64 to 66, a closer limit than is
and wipe dry with soft cloth. Place the individual balls on a
found in the ANSI requirement.
suitable holder and by means of a microscope, measure to the
nearest 0.01 mm the scar diameters both parallel (horizontal)
8. Preparation of Apparatus
and normal (vertical) to the striations in the scar surface of one
8.1 Thoroughly clean four new test balls, ball pot, and
of the three test balls.
chuck assemblies by first washing with Stoddard solvent
9.9.2 Option B—Retain the balls in the ball pot. Wipe
(Warning—See 7.1) and then ASTM n-heptane (Warning—
excess grease from the balls and ball pot. Wash the ball
See 7.2), and allow to air dry.
surfaces with Stoddard solvent and then n-heptane. Using a
8.2 Donotusesolventssuchascarbontetrachlorideorother
microscope, measure to the nearest 0.01 mm the scar diameters
solvents that may inherently possess extreme pressure proper-
both parallel (horizontal) and normal (vertical) to the striations
ties which may affect the results.
in the scar surface of one of the three test balls. Measurement
8.3 Lower the crosshead by raising the lever arm. Lock the
by microscope of the scar diameters on all three balls rather
lever arm in the raised position by means of a locking
than one ball as outlined in OptionsAor B may be made if the
arrangement for that purpose.
operator so desires.
9. Procedure
9.10 Record(Table1,Column2)forthe784N(80kgf)load
9.1 Bring lubricant to be tested to 27 6 8°C (80 6 15°F). the average scar diameter by any one of the three techniques
9.2 Completelyfilltheballpotwiththelubricatinggreaseto described in 9.9. Compare this average scar diameter (Table 1,
betested,avoidingtheinclusionofairpockets.Imbedthethree
Column 3). Discard the balls. If the average scar diameter is
steel test balls in the grease. Place the lock ring carefully over
notmorethan5 %fromthecompensationscardiameter,repeat
the three balls and screw down the lock nut securely (7.2).
the test at the next higher load (Table 1, Column 1), and again
Scrape off the excess grease pushed onto the lock nut.
compare scar diameters. Continue this procedure until the last
nonseizure load is determined.
NOTE 3—Subsequent independent investigations reported in 1971 by
several laboratories indicate that optimum test repeatability is obtained
9.11 If the measured scar diameter for the 784 N (80 kgf)
when the force on the lock-down nut is maintained within the range 50 6
load is more than 5 % from the compensation scar diameter,
5 ft·lbf (686 7 N·m), applied and measured by means of a torque wrench.
the next run is made at the next lower load (Table 1, Column
Significantly lower weld points were obtained when the force applied was
1). Continue this procedure until the last nonseizure load is
approximately 100 ft·lbf (136 N·m).
determined.
9.3 Press one ball into the ball chuck and mount the chuck
into chuckholder.
NOTE 5—When the optional friction-measuring device is used, the last
9.4 Examine the ball chuck carefully before each run. The nonseizure load is detected by a gradual transverse movement of the
indicating pen.
chuck is continually subjected to wear and seizure and should
be replaced when it will not fit into the ball chuck-holder tight
9.12 Make additional runs at consecutively higher test loads
enough to support its own weight, or if the ball seat shows
(Table 1, Column 1), recording the measured scar diameter(s)
signs of seizure.
and discarding test balls, until welding occurs. Make a check
9.5 Install the ball pot assembly on the test apparatus in
run at this point. If welding does not occur on the check run,
contact with the fourth ball. Place the mounting disk between
then repeat the test at the next higher load until welding is
ball pot and thrust bearing.
verified.
9.6 Place the weight tray and weights on the horizontal arm
9.13 Shut off the motor immediately to prevent damage to
in the correct notch for a base test load of 784 N (80 kgf).
the tester. Excessive wear or seizure of the ball and ball chuck
Release the lever arm and gently apply (Note 4) the test load to
may result if caution is not observed.Welding may be detected
the balls, making certain the ball pot assembly and mounting
by any or all of the following:
disk are centered. If the optional friction-measuring device is
used, connect the calibrated arm on the ball pot to the indicator
(1) Iffriction-measuringdeviceisused,asharptransverse
spring by means of the clip and wire, placing clip and indicator
movement of the indicating pen.
support over the numbers which correspond to the applied
(2) Increased noise level of motor.
load.
(3) Smoking from the ball pot.
NOTE 4—Shock-loading should be avoided as it may deform the balls
(4) A sudden drop in the lever arm.
permanently.
9.7 Start the motor and run for 10 6 0.2 s. The time for the
10. Calculations and Reports
apparatus to “coast” to a stop is not considered.
10.1 Corrected Load—Calculate and record (Table 1, Col-
9.8 Remove the load from the balls by raising the lever arm
umn 5) for each applied load between the last nonseizure load
and locking it in raised position. If the friction-measuring
and weld point using the equation:
device is used, remove clip and wire. Remove the ball pot
assembly; remove the chuck and discard the ball. Corrected load, kgf 5 LD /X (2)
h
D2596–97 (2008)
TABLE 1 Suggested Form for Recording Test Results
Column 6 Column 7
Column 1 Column 2 Scar Column 3 Scar Column 4 Scar Column 5 Average Column 9
Compensation C
...
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