1、Designation: D 2596 97 (Reapproved 2002)e1An American National StandardStandard Test Method forMeasurement of Extreme-Pressure Properties of LubricatingGrease (Four-Ball Method)1This standard is issued under the fixed designation D 2596; the number immediately following the designation indicates the
2、 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.This standard has been approved for use by agencies of the Dep
3、artment of Defense.e1NOTEWarning notes were placed in the text editorially in May 2002.1. Scope1.1 This test method covers the determination of the load-carrying properties of lubricating greases. Two determinationsare made:1.1.1 Load-Wear Index (formerly called Mean-Hertz Load),and1.1.2 Weld Point,
4、 by means of the Four-Ball Extreme-Pressure (EP) Tester.1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsib
5、ility 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 Documents2.1 ASTM Standards:D 235 Specification for Mineral Spir
6、its (Petroleum Spirits)(Hydrocarbon Dry Cleaning Solvent)22.2 American National Standard:B3.12 Metal Balls33. Terminology3.1 Definitions:3.1.1 compensation line, na line of plot on log-log paperwhere the coordinates are scar diameter in millimetres andapplied load in kilograms-force (or Newtons) obt
7、ained underdynamic conditions.3.1.1.1 DiscussionShown in Fig. 1 as line ABE.3.1.2 compensation scar diameterthe average diameter, inmillimetres, of the wear scar on the stationary balls caused bythe rotating ball under an applied load in the presence of alubricant, but without causing either seizure
8、 or welding.3.1.3 corrected load, nthe load in kilograms-force (orNewtons) obtained by multiplying the applied load by the ratioof the Hertz scar diameter to the measured scar diameter at thatload.3.1.3.1 DiscussionIn this test method, the corrected loadis calculated for each run.3.1.4 hertz line, n
9、a line of plot on log-log paper where thecoordinates are scar diameter in millimetres and applied load inkilograms-force (or Newtons) obtained under static conditions.3.1.4.1 DiscussionShown in Fig. 1 as a hertz line.3.1.5 hertz scar diameter, nthe average diameter, inmillimetres, of an indentation
10、caused by the deformation of theballs under static load (prior to test). It may be calculated fromthe equation:1This method is under the jurisdiction of ASTM Committee D02 on PetroleumProducts and Lubricants and is the direct responsibility of Subcommittee D02.G0.04on Functional Tests - Tribology.Cu
11、rrent edition approved June 10, 1997. Published October 1997. Originallypublished as D 2596 67 T. Last previous edition D 2596 96.2Annual Book of ASTM Standards, Vol 06.04.3Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.FIG. 1 Schematic Plot of Sca
12、r Diameter Versus Applied Load1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Dh5 8.73 3 102P!1/3(1)where:Dhis the Hertz diameter of the contact area in millimetres andP is the static applied load in kilograms-force.3.1.6 immediate s
13、eizure region, nthat region of the scar-load curve characterized by seizure or welding at the startup orby large wear scars.3.1.6.1 DiscussionUnder conditions of this test method,the immediate seizure region is shown by line CD. Also, initialdeflection of indicating pen on the optional friction-meas
14、uringdevice is larger than with nonseizure loads.3.1.7 incipient seizure or initial seizure region, nthatregion at which, with an applied load, there is a momentarybreakdown of the lubricating film.3.1.7.1 DiscussionThis breakdown is noted by a suddenincrease in the measured scar diameter, shown in
15、Fig. 1 as lineBC, and a momentary deflection of the indicating pen of theoptional friction-measuring device.3.1.8 last nonseizure load, nthe last load at which themeasured scar diameter is not more than 5 % greater than thecompenation value at that load.3.1.8.1 DiscussionShown in Fig. 1 as Point B.3
16、.1.9 load-wear index (or the load-carrying property of alubricant), nan index of the ability of a lubricant to preventwear at applied loads.3.1.9.1 DiscussionUnder the conditions of this test, spe-cific loadings in kilograms-force (or Newtons) having intervalsof approximately 0.1 logarithmic units,
17、are applied to the threestationary balls for ten runs prior to welding. The load wearindex is the average of the corrected loads determined for theten applied loads immediately preceding the weld point.3.1.10 weld point, nthe lowest applied load at whichsliding surfaces seize and then weld.3.1.10.1
18、DiscussionUnder the conditions of this test, thelowest applied load in kilograms-force (or Newtons) at whichthe rotating ball seizes and then welds to the three stationaryballs, indicating the extreme-pressure level of the lubricatinggrease has been exceeded. See Fig. 1, Point D.3.1.10.2 DiscussionS
19、ome lubricating greases do not al-low true welding, and extreme scoring of the three stationaryballs results. In such cases, the applied load which produces amaximum scar diameter of 4 mm is reported as the weld point.4. Summary of Test Method4.1 The tester is operated with one steel ball under load
20、rotating against three steel balls held stationary in the form ofa cradle. The rotating speed is 1770 6 60 rpm. Lubricatinggreases are brought to 27 6 8C (80 6 15F) and thensubjected to a series of tests of 10-s duration at increasing loadsuntil welding occurs.5. Significance and Use5.1 This test me
21、thod, used for specification purposes, dif-ferentiates between lubricating greases having low, medium,and high level of extreme-pressure properties. The results donot necessarily correlate with results from service.45.2 It is noted that lubricating greases that have as their fluidcomponent a silicon
22、e, halogenated silicone, or a mixturecomprising silicone fluid and petroleum oil, are not applicableto this method of test.6. Apparatus6.1 Four-Ball Extreme-Pressure Lubricant Tester,5illus-trated in Fig. 2.NOTE 1It is important to distinguish between the Four-Ball EP Testerand the Four-Ball Wear Te
23、ster. The Four-Ball Wear Tester can be usedunder a variety of test conditions at loads up to 490 N (50 kgf). TheFour-Ball EP Tester is designed for testing under more severe conditionsand lacks the sensitivity necessary for the Four-Ball Wear Test.6.2 Microscope,5equipped with calibrated measuring s
24、caleand readable to an accuracy of 0.01 mm.6.3 Timer, graduated in tenths of a second.NOTE 2Optional equipment with Four-Ball apparatus consists of afriction-measuring device electrically driven and conveniently graduatedin 10-s markings.7. Materials7.1 Stoddard Solvent Specifications D 235.(Warning
25、Combustible. Health hazard.)7.2 ASTM n-Heptane6(WarningFlammable. Health haz-ard.)4Further details on this method may be found in: Sayles, F. S., et al, NationalLubricating Grease Institute Spokesman, Vol 32, No. 5, August 1968, pp. 162167.5Falex Corp., 1020 Airpark Dr., Sugar Grove, IL 60554, Micro
26、scopes 103.10 Aand 103.10 B have been found satisfactory for this purpose.6Described in the Annual Book of ASTM Standards, Vol 05.04, Motor Fuels,Section I, Annex 2, Section A2.7, Reference Materials.FIG. 2 Sectional View of Four-Ball EP TesterD 2596 97 (2002)e127.3 Test Balls7Test balls shall be ch
27、rome alloy steel, madefrom AISI standard steel No. E-52100, with diameter of 12.7mm (0.5 in.), Grade 25 EP (Extra Polish). Such balls aredescribed in ANSI Specifications B 3, for Metal Balls. TheExtra-Polish finish is not described in that specification. TheRockwell C hardness shall be 64 to 66, a c
28、loser limit than isfound in the ANSI requirement.8. Preparation of Apparatus8.1 Thoroughly clean four new test balls, ball pot, andchuck assemblies by first washing with Stoddard solvent(WarningSee 7.1) and then ASTM n-heptane (WarningSee 7.2), and allow to air dry.8.2 Do not use solvents such as ca
29、rbon tetrachloride or othersolvents that may inherently possess extreme pressure proper-ties which may affect the results.8.3 Lower the crosshead by raising the lever arm. Lock thelever arm in the raised position by means of a lockingarrangement for that purpose.9. Procedure9.1 Bring lubricant to be
30、 tested to 27 6 8C (80 6 15F).9.2 Completely fill the ball pot with the lubricating grease tobe tested, avoiding the inclusion of air pockets. Imbed the threesteel test balls in the grease. Place the lock ring carefully overthe three balls and screw down the lock nut securely (7.2).Scrape off the ex
31、cess grease pushed onto the lock nut.NOTE 3Subsequent independent investigations reported in 1971 byseveral laboratories indicate that optimum test repeatability is obtainedwhen the force on the lock-down nut is maintained within the range 50 65 ftlbf (686 7 Nm), applied and measured by means of a t
32、orque wrench.Significantly lower weld points were obtained when the force applied wasapproximately 100 ftlbf (136 Nm).9.3 Press one ball into the ball chuck and mount the chuckinto chuckholder.9.4 Examine the ball chuck carefully before each run. Thechuck is continually subjected to wear and seizure
33、 and shouldbe replaced when it will not fit into the ball chuck-holder tightenough to support its own weight, or if the ball seat showssigns of seizure.9.5 Install the ball pot assembly on the test apparatus incontact with the fourth ball. Place the mounting disk betweenball pot and thrust bearing.9
34、.6 Place the weight tray and weights on the horizontal armin the correct notch for a base test load of 784 N (80 kgf).Release the lever arm and gently apply (Note 4) the test load tothe balls, making certain the ball pot assembly and mountingdisk are centered. If the optional friction-measuring devi
35、ce isused, connect the calibrated arm on the ball pot to the indicatorspring by means of the clip and wire, placing clip and indicatorsupport over the numbers which correspond to the appliedload.NOTE 4Shock-loading should be avoided as it may deform the ballspermanently.9.7 Start the motor and run f
36、or 10 6 0.2 s. The time for theapparatus to “coast” to a stop is not considered.9.8 Remove the load from the balls by raising the lever armand locking it in raised position. If the friction-measuringdevice is used, remove clip and wire. Remove the ball potassembly; remove the chuck and discard the b
37、all.9.9 Measure the scar diameter of test balls as follows:9.9.1 Option ARemove the lock nut and release the testballs. Clean the balls with Stoddard solvent and then n-heptane,and wipe dry with soft cloth. Place the individual balls on asuitable holder and by means of a microscope, measure to thene
38、arest 0.01 mm the scar diameters both parallel (horizontal)and normal (vertical) to the striations in the scar surface of oneof the three test balls.9.9.2 Option BRetain the balls in the ball pot. Wipeexcess grease from the balls and ball pot. Wash the ballsurfaces with Stoddard solvent and then n-h
39、eptane. Using amicroscope, measure to the nearest 0.01 mm the scar diametersboth parallel (horizontal) and normal (vertical) to the striationsin the scar surface of one of the three test balls. Measurementby microscope of the scar diameters on all three balls ratherthan one ball as outlined in Optio
40、ns A or B may be made if theoperator so desires.9.10 Record (Table 1, Column 2) for the 784 N (80 kgf) loadthe average scar diameter by any one of the three techniquesdescribed in 9.9. Compare this average scar diameter (Table 1,Column 3). Discard the balls. If the average scar diameter isnot more t
41、han 5 % from the compensation scar diameter, repeatthe test at the next higher load (Table 1, Column 1), and againcompare scar diameters. Continue this procedure until the lastnonseizure load is determined.9.11 If the measured scar diameter for the 784 N (80 kgf)load is more than 5 % from the compen
42、sation scar diameter,the next run is made at the next lower load (Table 1, Column1). Continue this procedure until the last nonseizure load isdetermined.NOTE 5When the optional friction-measuring device is used, the lastnonseizure load is detected by a gradual transverse movement of theindicating pe
43、n.9.12 Make additional runs at consecutively higher test loads(Table 1, Column 1), recording the measured scar diameter(s)and discarding test balls, until welding occurs. Make a checkrun at this point. If welding does not occur on the check run,then repeat the test at the next higher load until weld
44、ing isverified.9.13 Shut off the motor immediately to prevent damage tothe tester. Excessive wear or seizure of the ball and ball chuckmay result if caution is not observed. Welding may be detectedby any or all of the following:(1) If friction-measuring device is used, a sharp transversemovement of
45、the indicating pen.(2) Increased noise level of motor.(3) Smoking from the ball pot.(4) A sudden drop in the lever arm.7Steel balls meeting this description were used in developing the precision of thetest. They are available from ball bearing or laboratory equipment manufacturersand distributors. A
46、ll balls used in one test should be taken from one carton (of 500balls) as received from the supplier.D 2596 97 (2002)e1310. Calculations and Reports10.1 Corrected LoadCalculate and record (Table 1, Col-umn 5) for each applied load between the last nonseizure loadand weld point using the equation:Co
47、rrected load, kgf 5 LDh/X (2)where:L = applied load, kgf, that is, total weight applied (trayand weights) multiplied by lever arm ratio,Dh= Hertz scar diameter, mm, andX = average scar diameter, mm.10.2 Load-Wear Index8Calculate and report the Load-Wear Index (formerly Mean-Hertz Load) in kilograms-
48、forceusing the equation:Load2Wear Index, kgf 5 A/10 (3)where:A = sum of the corrected loads determined for the tenapplied loads immediately preceding the weld point(Note 6).NOTE 6If tests applied to the lubricant indicate it follows thecompensation line, then A may be defined as:A = sum of corrected
49、 loads plus compensation line corrected loads, for theten applied loads immediately preceding the weld point.For convenience, Table 2 has been constructed to give the compensationline corrected load for any portion of the compensation line. This value isobtained by noting the intersection of the last nonseizure load and weldload values. For example: the last nonseizure load of a lubricant was foundto be 490 N (50 kgf). Subsequent runs in the seizure portion of the curvewere made at 618, 784, 981, 1236, and 1569-N (63, 80, 100, 126, and1
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