ASTM D2596-1997(2008) Standard Test Method for Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method).pdf

1、Designation: D 2596 97 (Reapproved 2008)An 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 y

2、ear 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.This standard has been approved for use by agencies of the Depart

3、ment of Defense.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, by means of the Four-Ball Extreme-Pressure (EP) Tester.1.2 The values

4、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 theresponsibility of the user of this standard to establish appro-priate safety and

5、 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:2D 235 Specification for Mineral Spirits (Petroleum Spirits)(Hydrocarbon Dry Cleaning Solvent)2.2 American

6、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) obtained underdynamic conditions.3.1.1.1 DiscussionShown in Fig. 1 as line

7、 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 or welding.3.1.3 corrected load, nthe load in kilograms-force (orNewto

8、ns) 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, na line of plot on log-log paper where thecoordinates are scar diameter

9、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 caused by the deformation of theballs under static load (prior to test)

10、. It may be calculated fromthe equation:Dh5 8.73 3 102P!1/3(1)where:Dh= Hertz diameter of the contact area in millimetres, and1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.G0.04 on Functional

11、Tests - Tribology.Current edition approved May 1, 2008. Published September 2008. Originallyapproved in 1967. Last previous edition approved in 2002 as D 259697(2002)1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual

12、 Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.FIG. 1 Schematic Plot of Scar Diameter Versus Applied Load1Copyrig

13、ht ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.P = static applied load in kilograms-force.3.1.6 immediate seizure region, nthat region of the scar-load curve characterized by seizure or welding at the startup orby large wear scars.3.1.6.1 D

14、iscussionUnder conditions of this test method,the immediate seizure region is shown by line CD. Also, initialdeflection of indicating pen on the optional friction-measuringdevice is larger than with nonseizure loads.3.1.7 incipient seizure or initial seizure region, nthatregion at which, with an app

15、lied 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 Fig. 1 as lineBC, and a momentary deflection of the indicating pen of theoptional friction-measuring device.3.1.8 last nonseizure loa

16、d, 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.3.1.9 load-wear index (or the load-carrying property of alubricant), nan index of the ability of a lubricant to preventwear at applied

17、 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, are applied to the threestationary balls for ten runs prior to welding. The load wearindex is the average of the corrected loads dete

18、rmined 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 DiscussionUnder the conditions of this test, thelowest applied load in kilograms-force (or Newtons) at whichthe rotating ball seizes

19、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 DiscussionSome lubricating greases do not al-low true welding, and extreme scoring of the three stationaryballs results. In such cases, the appl

20、ied 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 loadrotating against three steel balls held stationary in the form ofa cradle. The rotating speed is 1770 6 60 rpm. Lubricatinggreases ar

21、e 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 method, used for specification purposes, dif-ferentiates between lubricating greases having low, medium,and high level of extreme-press

22、ure properties. The results donot necessarily correlate with results from service.45.2 It is noted that lubricating greases that have as their fluidcomponent a silicone, halogenated silicone, or a mixturecomprising silicone fluid and petroleum oil, are not applicableto this method of test.6. Apparat

23、us6.1 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 Tester. 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 i

24、s designed for testing under more severe conditionsand lacks the sensitivity necessary for the Four-Ball Wear Test.6.2 Microscope,5equipped with calibrated measuring scaleand readable to an accuracy of 0.01 mm.6.3 Timer, graduated in tenths of a second.NOTE 2Optional equipment with Four-Ball apparat

25、us consists of afriction-measuring device electrically driven and conveniently graduatedin 10-s markings.7. Materials7.1 Stoddard Solvent Specifications D 235.(WarningCombustible. Health hazard.)7.2 ASTM n-Heptane6(WarningFlammable. Health haz-ard.)7.3 Test Balls7Test balls shall be chrome alloy ste

26、el, madefrom AISI standard steel No. E-52100, with diameter of 12.7mm (0.5 in.), Grade 25 EP (Extra Polish). Such balls are4Further details on this test method may be found in: Sayles, F. S., et al, NationalLubricating Grease Institute Spokesman, Vol 32, No. 5, August 1968, pp. 162167.5The sole sour

27、ce of supply of the apparatus (microscopes 103.10 A and 103.10B) known to the committee at this time is Falex Corporation, 1020 Airpark Dr.,Sugar Grove, IL, 60554-9585. If you are aware of alternative suppliers, pleaseprovide this information to ASTM International Headquarters. Your comments willrec

28、eive careful consideration at a meeting of the responsible technical committee,1which you may attend.6Described in the 1998 Annual Book of ASTM Standards, Vol 05.04, MotorFuels, Section I, Annex 2, Section A2.7, Reference Materials.7Steel balls meeting this description were used in developing the pr

29、ecision of thetest. They are available from ball bearing or laboratory equipment manufacturersand distributors. All balls used in one test should be taken from one carton (of 500balls) as received from the supplier.FIG. 2 Sectional View of Four-Ball EP TesterD 2596 97 (2008)2described in ANSI Specif

30、ications B3.12, for Metal Balls. TheExtra-Polish finish is not described in that specification. TheRockwell C hardness shall be 64 to 66, a closer limit than isfound in the ANSI requirement.8. Preparation of Apparatus8.1 Thoroughly clean four new test balls, ball pot, andchuck assemblies by first wa

31、shing 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 carbon tetrachloride or othersolvents that may inherently possess extreme pressure proper-ties which may affect the results.8.3 Lower the crosshead by raising th

32、e lever arm. Lock thelever arm in the raised position by means of a lockingarrangement for that purpose.9. Procedure9.1 Bring lubricant to be 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 threes

33、teel 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 excess grease pushed onto the lock nut.NOTE 3Subsequent independent investigations reported in 1971 byseveral laboratories indicate that optimum test repeatabili

34、ty 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 torque 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 an

35、d mount the chuckinto chuckholder.9.4 Examine the ball chuck carefully before each run. Thechuck is continually subjected to wear and seizure 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 Ins

36、tall the ball pot assembly on the test apparatus incontact with the fourth ball. Place the mounting disk betweenball pot and thrust bearing.9.6 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 (N

37、ote 4) the test load tothe balls, making certain the ball pot assembly and mountingdisk are centered. If the optional friction-measuring device 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

38、which correspond to the appliedload.NOTE 4Shock-loading should be avoided as it may deform the ballspermanently.9.7 Start the motor and run for 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 ra

39、ised position. If the friction-measuringdevice is used, remove clip and wire. Remove the ball potassembly; remove the chuck and discard the ball.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 a

40、nd then n-heptane,and wipe dry with soft cloth. Place the individual balls on asuitable holder and by means of a microscope, measure to thenearest 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 Opti

41、on BRetain the balls in the ball pot. Wipeexcess grease from the balls and ball pot. Wash the ballsurfaces with Stoddard solvent and then n-heptane. Using amicroscope, measure to the nearest 0.01 mm the scar diametersboth parallel (horizontal) and normal (vertical) to the striationsin the scar surfa

42、ce of one of the three test balls. Measurementby microscope of the scar diameters on all three balls ratherthan one ball as outlined in Options 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 te

43、chniquesdescribed in 9.9. Compare this average scar diameter (Table 1,Column 3). Discard the balls. If the average scar diameter isnot more than 5 % from the compensation scar diameter, repeatthe test at the next higher load (Table 1, Column 1), and againcompare scar diameters. Continue this procedu

44、re 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 compensation 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 5

45、When the optional friction-measuring device is used, the lastnonseizure load is detected by a gradual transverse movement of theindicating pen.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 weld

46、ing 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 welding 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

47、 not observed. Welding may be detectedby any or all of the following:(1) If friction-measuring device is used, a sharp transversemovement of the indicating pen.(2) Increased noise level of motor.(3) Smoking from the ball pot.(4) A sudden drop in the lever arm.10. Calculations and Reports10.1 Correct

48、ed LoadCalculate and record (Table 1, Col-umn 5) for each applied load between the last nonseizure loadand weld point using the equation:D 2596 97 (2008)3Corrected load, kgf 5 LDh/X (2)where:L = applied load, kgf, that is, total weight applied (trayand weights) multiplied by lever arm ratio,Dh= Hert

49、z scar diameter, mm, andX = average scar diameter, mm.10.2 Load-Wear Index (see Note 6)Calculate and reportthe Load-Wear Index (formerly Mean-Hertz Load) inkilograms-force using 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 7).NOTE 6The method of calculation was amended in 1982. For alubricant with a weld point of 400 kg or less the Load Wear Index is thesame with the old and the present method of calculation.NOTE 7If tests