1、Designation: D7420 10Standard 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. Scope1.1 This test method c
4、overs 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 S
5、I 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 and health
6、 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3A295 Specification for High-Carbon Anti-Friction BearingSteelD217 Test Methods for Cone Penetration of LubricatingGreaseD4175 Terminology Relating to Petroleum, PetroleumProd
7、ucts, 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 Wear and Erosion2.2 DIN Standards:4DIN 51631:
8、1999 Special-boiling-point spirits - Require-ments and testingDIN 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 1
9、7230-1980)DIN EN ISO 13565-2:1998 Geometrical Product Specifica-tions (GPS) - Surface texture: Profile method - Surfaceshaving stratified functional properties - Part 2: Heightcharacterization using the linear material ratio curve2.3 ISO Standard:5ISO 1250:1972 Mineral solvents for paints - White sp
10、iritsand related hydrocarbon solvents3. Terminology3.1 Definitions:3.1.1 break-in, nin tribology, an initial transition processoccurring in newly established wearing contacts, often accom-panied by transients in coefficient of friction or wear rate, orboth, which are uncharacteristic of the given tr
11、ibologicalsystems long-term behavior. G401This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.G0 on Lubricating Grease.Current edition approved March 1, 2010. Published April 2010. DOI:10.1520/D74201
12、0.2TRW Fahrwerksysteme (Chassis Systems), 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
13、 website.4Available from Beuth Verlag GmbH (DIN- DIN Deutsches Institut furNormung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http:/www.en.din.de.5Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland,
14、http:/www.iso.ch.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2 coeffcient of friction, or , nin tribology, thedimensionless ratio of the friction force (F) between twobodies to the normal force (N) pressing these bodies toget
15、her.G403.1.3 lubricant, nany material interposed between twosurfaces that reduces the friction or wear between them.D41753.1.4 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
16、 system and immobilizes the liquid lubricant bysurface tension and other physical forces. Other ingredients arecommonly included to impart special properties.3.1.5 nitro-carburizationnitro-carburizing is not definedin the ASTM Dictionary of Engineering Science and Technol-ogy, but is defined in DIN
17、EN 10025-1:2005.3.1.6 Ra (C.L.A.), nin measuring surface finish, the arith-metic average of the absolute distances of all profile pointsfrom the mean line for a given distance. Amstutz63.1.7 Rpk, nReduced peak height according to DIN ENISO 13565-2:1998. Rpk is the mean height of the peak stickingout
18、 above the core profile section.3.1.8 Rvk, nReduced valley height according to DIN ENISO 13565-2:1998. Rvk is the mean 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 th
19、e assessmentlength. Amstutz73.1.10 thickener, nin lubricating grease, a substancecomposed of finely divided particles dispersed in a liquidlubricant to form the products structure. D2173.1.10.1 DiscussionThe thickener can be fibers (such asvarious metallic soaps) or plates or spheres (such as certai
20、nnon-soap thickeners) which are insoluble or, at most, only veryslightly soluble in the liquid lubricant. The general 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 Definit
21、ions of Terms Specific to This Standard:3.2.1 metal specimen, nrepresented by the lower speci-men. Ball stud or ball 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, nloca
22、lized adhesion of polymer onto metalbetween the rubbing surfaces of the test pieces.3.2.3.1 DiscussionIn this test method, seizure 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
23、example, see Test Method D5706).3.2.4 SRV, nSchwingung, Reibung, Verschlei (Ger-man); oscillating, friction, 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
24、 disk with lubricant (grease) betweenthem. Test load is fixed to 2000 N using a test temperature of50C and a stroke of 1.5 mm during a test time of 2 h.NOTE 1Test frequency, stroke length, temperature, and polymericdisk and disk material can be varied to simulate field conditions. Thepolymeric disk
25、having three flat pins yields surface-on-flat contactgeometry.NOTE 2This test can not be executed with SRV I and SRV II models,as they are limited to 1200 N and 1400 N, respectively. The SRV III andSRV IV model are from the test chamber and operating conditionsidentical, but the SRV IV model allows
26、to tilt and rotate the test chamber.Both are fully computer controlled. This test runs in the SRV IV modelshorizontally and untilted.5. Significance and Use5.1 This test method can be used to quickly determine thelubricating ability of greases lubricating automotive plasticsocket suspension joints.
27、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, dis-crete, and constant parame
28、ter combinations. Users of this testmethod should determine whether results correlate with fieldperformance or other applications prior to commercialization.6. Apparatus6.1 SRV Test Machine,8See Fig. 1 and Fig. 2.7. Reagents and Materials7.1 Polymeric Test Disk with Three Pins, = 18.2+0.2-mmdiameter
29、. 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 Lower Test Disk8Vacuum ar
30、c 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, 62 6 1 HRC hardness, t
31、he surfaces ofthe disk being lapped and free of lapping raw materials. Thetopography of the disk will be determined by four values:0.5 m Rz 0.650 m0.35 m C.L.A. (Ra) 0.050 m0.020 m Rpk 0.035 m0.050 m Rvk 0.075 m (24 6 0.5mm diameter by7.8 6 0.1mm thick)6Amstutz, Hu, “Surface Texture: The Parameters,
32、” Bulletin MI-TP-003-0785,Sheffield Measurement Division, Warner and Swasey, 1985, p. 217Amstutz, Hu, “Surface Texture: The Parameters”, Bulletin MI-TP-003-0785,Sheffield Measurement Division, Warner and Swasey, 1985, pp. 2931.8The sole source of supply of the apparatus known to the committee at thi
33、s timeis Optimol Instruments GmbH, Westendstr. 125, D-80339 Munich, Germany. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may
34、 attend.D7420 102If other surface roughnesses are applied, they have to bemeasured and stated in the report. The type of coating and/orthermomechanical treatment has to be reported.NOTE 3The steel 41CrS4 (DIN 1.7039) is also used in practice. Thetest disks should be polished to RZ1-1.5 m and can be
35、carbo-nitrided.7.3 Grease, Store in a sealed container prior to testing.(Different greases have different characteristics for storagestability and shelf life and users should be guided by their ownknowledge of the material to be tested, or by the recommen-dation of the supplier.)7.4 Cleaning Solvent
36、, Special boiling point spirit type 2-Ain accordance with DIN 51631 or ISO 1250. (WarningFlammable. Health hazard.)8. Preparation of Apparatus8.1 SRV Machine Generation III and IVTurn on the testmachine and the computer, and allow them to warm up for 15min prior to running tests.9. Procedure9.1 Chec
37、k the polymeric disk for visible damage orscratches. Clean the polymeric disk and the steel disk bywiping the surfaces with laboratory tissue soaked with thecleaning solvent. Repeat wiping until no dark residue appearson the tissue. Immerse the steel disk in a beaker of the cleaningsolvent under ult
38、rasonic 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 eachtest.NOTE 4Ensure that the polymer and the constituents of the blend isresistant to the solvent. If the binder is not resistant to th
39、e solvent, wipeonly the polymeric disk surface with a laboratory tissue.9.2 Prior to testing, determine thickness of plastic specimenin all three contact surfaces (pins) by a micrometer gaugecaliper rule. Document measurement readings in the test report.9.3 Place the grease using a calibration ring
40、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 facing the adapter and the test surface with thethree pins pointing upwards. Align the polymeric test disk asshown in Fig. 3.NOTEAbo
41、ve: Model III; Below: Model IVFIG. 1 SRV Test Machine1. Oscillation drive rod 6. Electrical Resistance Heater2. Test Ball Holder 7. Resistance Thermometer3. Load Rod 8. Test Disk Holder4. Test Ball 9. Piezoelectric Measuring Device5. Test Disk 10. Receiving BlockFIG. 2 Test Chamber Elements (Schemat
42、ic) of SRV Test MachineD7420 1039.5 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 are immersed in thegrease.9.6 Place a 10-mm steel ball in the ring/area specimenholder and tight
43、en it.9.7 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 andthe lower test disk on the
44、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 of a clamping bow.9.11 In t
45、he SRV basic software, enter the following testparameters:Frequency = 50 HzStroke = 1.5 mmTemperature = 50CLoad 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. Report10.1 During testing,
46、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:10.2.1 Temperature, C,10.2.2 Stroke, mm,10.2.
47、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 Pretreatment or coating of steel disk.NOTE 5
48、Some 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 Clean polymeric and steel specimens af
49、ter 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 specimen pins by micrometer gauge. Changes in thicknessare interpreted as “linear wear” and shall be documented in thetest report.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 st
