ASTM D7420-17 Standard Test Method for Determining Tribomechanical Properties of Grease Lubricated Plastic Socket Suspension Joints Using a High-Frequency, Linear-Oscillation (SRV) Test Machine.pdf

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1、Designation: D7420 17Standard Test Method forDetermining Tribomechanical Properties of GreaseLubricated Plastic Socket Suspension Joints Using a High-Frequency, Linear-Oscillation (SRV) Test Machine1This standard is issued under the fixed designation D7420; the number immediately following the desig

2、nation indicates the 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 () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method was originally

3、 published as bilingual company standard TRW 62 051 301 in June2002. TRW Fahrwerksysteme2transferred the copyright on Oct. 5, 2004 to standardization bodies. TheDIN 51834 working group has modified this standard by adding precision information based on roundrobin tests.1. Scope*1.1 This test method

4、covers a procedure for determining thefriction and wear behavior of grease lubricated plastic socketsuspension joints, for validation of suspension joint greasesand quality inspection for those greases under high-frequencylinear-oscillation motion using the SRV test machine.1.2 The values stated in

5、SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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, health,

6、and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of Internationa

7、l Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3A295 Specification for High-Carbon Anti-Friction BearingSteelD217 Test Methods for Cone Penetration of LubricatingGreaseD4175 Terminol

8、ogy Relating to Petroleum Products, LiquidFuels, and LubricantsD5706 Test Method for Determining Extreme PressureProperties of Lubricating Greases Using a High-Frequency, Linear-Oscillation (SRV) Test MachineE45 Test Methods for Determining the Inclusion Content ofSteelG40 Terminology Relating to We

9、ar and Erosion2.2 DIN Standards:4DIN EN 10025-1:2005 Hot rolled products of structuralsteels - Part 1: General technical delivery conditionsDIN EN ISO 683-17 Heat-treated steels, alloy steels andfree-cutting steels - Part 17: Ball and roller bearing steels(replaces DIN 17230-1980)DIN EN ISO 13565-2:

10、1998 Geometrical Product Specifica-tions (GPS) - Surface texture: Profile method - Surfaceshaving stratified functional properties - Part 2: Heightcharacterization using the linear material ratio curve3. Terminology3.1 Definitions:3.1.1 break-in, nin tribology, an initial transition processoccurring

11、 in newly established wearing contacts, often accom-panied by transients in coefficient of friction or wear rate, orboth, which are uncharacteristic of the given tribologicalsystems long-term behavior. G401This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid

12、Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.G0 on Lubricating Grease.Current edition approved Nov. 1, 2017. Published December 2017. Originallyapproved in 2010. Last previous edition approved in 2011 as D742011.DOI:10.1520/D742017.2TRW Fahrwerksysteme (Chassis Systems),

13、 D-50543, Dsseldorf, Germany.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from Beuth Verlag Gmb

14、H (DIN- DIN Deutsches Institut furNormung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http:/www.en.din.de.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis int

15、ernational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) C

16、ommittee.13.1.2 coeffcient of friction, or , nin tribology, thedimensionless ratio of the friction force (F) between twobodies to the normal force (N) pressing these bodies together.G403.1.3 lubricant, nany material interposed between twosurfaces that reduces the friction or wear between them. D4175

17、3.1.4 lubricating grease, na semifluid to solid product ofa dispersion of a thickener in a liquid lubricant. D2173.1.4.1 DiscussionThe dispersion of the thickener forms atwo-phase system and immobilizes the liquid lubricant bysurface tension and other physical forces. Other ingredients arecommonly i

18、ncluded to impart special properties.3.1.5 nitro-carburization, nnitro-carburizing is not de-fined in the ASTM Dictionary of Engineering Science andTechnology, but is defined in DIN EN 10025-1:2005.3.1.6 Ra (C.L.A.), nin measuring surface finish, the arith-metic average of the absolute distances of

19、all profile pointsfrom the mean line for a given distance. Amstutz53.1.7 Rpk, nReduced peak height according to DIN ENISO 13565-2:1998. Rpk is the mean height of the peak stickingout above the core profile section.3.1.8 Rvk, nReduced valley height according to DIN ENISO 13565-2:1998. Rvk is the mean

20、 depth of the valleyreaching into the material below the core profile section.3.1.9 Rz (DIN), nin measuring surface finish, the averageof all Ry values (peak to valley heights) in the assessmentlength. Amstutz63.1.10 thickener, nin lubricating grease, a substance com-posed of finely divided particle

21、s dispersed in a liquid lubricantto form the products structure. D2173.1.10.1 DiscussionThe thickener can be fibers (such asvarious metallic soaps) or plates or spheres (such as certainnon-soap thickeners) which are insoluble or, at most, only veryslightly soluble in the liquid lubricant. The genera

22、l require-ments are that the solid particles be extremely small, uniformlydispersed, and capable of forming a relatively stable, gel-likestructure with the liquid lubricant.3.2 Definitions of Terms Specific to This Standard:3.2.1 metal specimen, nrepresented by the lower speci-men. Ball stud or ball

23、 pins are also used as common synonym.3.2.2 plastic socket, nrepresented by the upper polymericdisk specimen. Plastic seat or beating is also used as commonsynonym.3.2.3 seizure, nlocalized fusion of metal between therubbing surfaces of the test pieces. D57063.2.3.1 DiscussionIn this test method, se

24、izure is indicatedby a sharp rise in the coefficient of friction, over steady state,of greater than 0.2 for over 20 s. In severe cases, a stoppage inthe motor will occur (for example, see Test Method D5706).3.3 Abbreviations:3.3.1 SRV, nSchwingung, Reibung, Verschlei (German);oscillating, friction,

25、wear (English translation).4. Summary of Test Method4.1 This test method is performed on SRV test machineusing a polymeric disk having three flat pins oscillating at 50Hz against a steel test disk with lubricant (grease) betweenthem. Test load is fixed to 2000 N using a test temperature of50C and a

26、stroke of 1.5 mm during a test time of 2 h.NOTE 1Test frequency, stroke length, temperature, and polymeric diskand disk material can be varied to simulate field conditions. The polymericdisk having three flat pins yields surface-on-flat contact geometry.NOTE 2This test can not be executed with SRV I

27、 and SRV II models,as they are limited to 1200 N and 1400 N, respectively. The SRV III andSRV IV models are from the test chamber and operating conditionsidentical, but the SRV IV model allows to tilt and rotate the test chamber.Both are fully computer controlled. This test runs in the SRV IV and 5m

28、odels horizontally and untilted. SRV III test machines after 1995 reach2000 N. SRV 4 and SRV 5 models can be equipped with a maximum testload unit of 2500 N.5. Significance and Use5.1 This test method can be used to quickly determine thelubricating ability of greases lubricating automotive plasticso

29、cket suspension joints. This test method has found wideapplication in qualifying greases used in chassis systems. Thistest method is a material and application oriented approachbased on inputs from field experiences for characterizing thetribological behavior (friction and wear) using random,discret

30、e, and constant parameter combinations. Users of thistest method should determine whether results correlate withfield performance or other applications prior to commercial-ization.6. Apparatus6.1 SRV Test Machine,7illustrated in Figs. 1-4.7. Reagents and Materials7.1 Polymeric Test Disk with Three P

31、ins, = 18.2+0.2-mmdiameter. Each pin has a diameter of = 3.0-mm (see Fig.X1.1). The plastic specimen should represent characteristicitems of an inner plastic socket surface. Specimens are moldedfrom original socket material; functional surfaces shall be freefrom scratches and any surface damages.7.2

32、 Lower Test Disk7Vacuum arc remelted (VAR) AISI52100 steel with a inclusion rating using Method D, TypeA, asseverity level number of 0.5 according to Test Methods E45and Specification A295 or a inclusion sum value K1 10according to DIN EN ISO 683-17 and spherodized annealed toobtain globular carbide

33、, 62 6 1 HRC hardness, the surfaces ofthe disk being lapped and free of lapping raw materials. Thetopography of the disk will be determined by four values:0.5 m 20sCoefficient of friction, f (cut-off value for one-off increase of level): 0.358.2.3 Test parameters:Frequency: 50 HzStroke: 1.50 mmTempe

34、rature: 50 CPre-load: 50 N for 30 sTest load: running in under 50 N for 30 s, then constant load of 2000 NTest duration: 120.5 min8.2.4 Sample rates for result-relevant measurement chan-nels:Coefficient of friction, f: # 32 msStroke: # 2sTest load: # 2sFrequency: # 2sTemperature: # 2s.NOTE 5For SRV

35、5 models, it is recommended to do one sampling perperiod (that is, 20 ms) for coefficient of friction and stroke.9. Procedure9.1 Check the polymeric disk for visible damage orscratches. Clean the polymeric disk and the steel disk bywiping the surfaces with laboratory tissue soaked with thecleaning s

36、olvent. Repeat wiping until no dark residue appearson the tissue. Immerse the steel disk in a beaker of the cleaningsolvent under ultrasonic vibration for 10 min. Dry the steel testdisk with a clean tissue to ensure no streaking occurs on thesurface. Generally, a new specimen should be used for each

37、test.NOTE 6Ensure that the polymer and the constituents of the blend isresistant to the solvent. If the binder is not resistant to the solvent, wipeonly the polymeric disk surface with a laboratory tissue.9.2 Prior to testing, determine thickness of plastic specimenin all three contact surfaces (pin

38、s) by a micrometer gaugecaliper rule. Document measurement readings in the test report.9.3 Place the grease using a calibration ring while ensuringthat the grease is applied to a height of 0.2-0.3 mm above themetal test disk.9.4 Place the cleaned polymeric test disk in the adapter withthe level side

39、 facing the adapter and the test surface with thethree pins pointing upwards. Align the polymeric test disk asshown in Fig. 5.9.5 Tighten the test disk by means of the three screws at theside of the adapter. Place the adapter holding the polymeric testdisk on the lower disk so that the three pins ar

40、e immersed in thegrease.9.6 Place a 10-mm steel ball in the ring/area specimenholder and tighten it.1. Base of the Receiving Block 7. Upper Specimen Holder2. Piezo Force Measurement Ele-ments8. Drive Rods of the Load Unit3. Supporting Surface (HeadPlate) of the Receiving Block9. Test Disk4. Lower Sp

41、ecimen Holder 10. Test Ball5. Position of the Electrical Resis-tance Heating and ResistanceThermometerFnNormal Force (Test Load)6. Oscillation Drive Rods FfFriction ForceFIG. 4 Test Chamber Elements of SRV Models 4 and 5FIG. 5 Test Geometry and Orientation of the Upper Polymeric PinSpecimen in Respe

42、ct to Oscillatory MotionD7420 1749.7 Place a small quantity of lubricant in the recess of theadapter.9.8 Place the specimen holder containing the ball into therecess of the adapter.9.9 Position the specimen combination comprising the ring/area holder and ball, the adapter with the polymeric disk and

43、the lower test disk on the test platform in the test chamber.Make sure that one pin of the polymeric test disk is pointingtowards the operator.9.10 Insert the ring-area specimen holder in the openings ofthe drive axles and tighten it with knurled screws. Slightlytighten the lower test disk by means

44、of a clamping bow.9.11 In the SRV basic software, enter the following testparameters:Frequency = 50 HzStroke = 1.5 mmTemperature = 50 CLoad 50 N for 30 s, then increase load to 2000 NTest duration = 120 min9.12 To fully tighten the specimen combination, follow theinstructions of the SRV software.10.

45、 Report10.1 During testing, friction coefficient f determined fromtest load Fnand friction load Ffis recorded as well as actualtesting temperature. Friction coefficient traces must be storedon data records.10.2 Report the following informationall parameters usedto evaluate material follows:10.2.1 Te

46、mperature, C,10.2.2 Stroke, mm,10.2.3 Frequency, Hz,10.2.4 Relative humidity,10.2.5 Brand name, type of thickener, type of base oil, andNLGI class of grease,10.2.6 Polymeric test disk material,10.2.7 Steel test disk material,10.2.8 Thickness of each pin prior to and after testing, and10.2.9 Pretreat

47、ment or coating of steel disk.NOTE 7Some polymers and components of the blends are sensitive tohumidity as it affects dimensional stability. If this is the case, place thepolymeric disks in a box with defined relative humidity (for example,50%) for 24 h prior to each measurement of thickness.10.3 Cl

48、ean polymeric and steel specimens after testing in anultrasound cleaning bath. The tribological test surfaces shallnot show any scratches or grooves, changes in color, ormaterial build-up. There shall be no bulges or flimsy fibers inthe peripheral area of the specimen. Detect thickness (height)of sp

49、ecimen pins by micrometer gauge. Changes in thicknessare interpreted as “linear wear” and must be documented in testreport.10.3.1 The thickness change on pins should not exceed 0.2mm.10.3.2 The metal disk shall not show significant changes intribologically stressed surface areas. Particularly no scratches,colored spots, and depressions shall be visible. Evaluation shallbe performed with microscope. Carbonitrided surfaces shallnot show damages of oxide layer.10.4 Report the linear wear as average of three pins and thecoefficien