1、Designation: D7420 17D7420 18Standard 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 t
2、he designation 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 or
3、iginally published as bilingual company standard TRW 62 051 301 in June2002.TRWFahrwerksysteme2 transferred 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 m
4、ethod covers a procedure for determining the friction and wear behavior of grease lubricated plastic socketsuspension joints, for validation of suspension joint greases and quality inspection for those greases under high-frequencylinear-oscillation motion using the SRV test machine.1.2 The values st
5、ated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety
6、, health, and environmental practices and determine the applicability ofregulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of Intern
7、ational Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3A295 Specification for High-Carbon Anti-Friction Bearing SteelD217 Test Methods for Cone Penetration of Lubricating GreaseD4175 T
8、erminology Relating to Petroleum Products, Liquid Fuels, and LubricantsD5706 Test Method for Determining Extreme Pressure Properties of Lubricating Greases Using a High-Frequency, Linear-Oscillation (SRV) Test MachineE45 Test Methods for Determining the Inclusion Content of SteelG40 Terminology Rela
9、ting to Wear and Erosion2.2 DIN Standards:4DIN EN 10025-1:2005 Hot rolled products of structural steels - Part 1: General technical delivery conditionsDIN EN ISO 683-17 Heat-treated steels, alloy steels and free-cutting steels - Part steelsPart 17: Ball and roller bearing steels(replaces DIN 17230-1
10、980)1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.G0 on Lubricating Grease.Current edition approved Nov. 1, 2017Dec. 1, 2018. Published December 2017January 2019. Originally ap
11、proved in 2010. Last previous edition approved in 20112017as D7420D7420 17.11. DOI:10.1520/D742017.2 TRW Fahrwerksysteme (Chassis Systems), D-50543, Dsseldorf, Germany.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual
12、Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from Beuth Verlag GmbH (DIN- DIN Deutsches Institut fur Normung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http:/www.en.din.de.This document is not an ASTM standard and is
13、intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the c
14、urrent versionof the standard as published by ASTM is to be considered the official document.*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 States1DIN EN ISO 13565-2:199813565
15、-2: 1998 Geometrical Product Specifications (GPS) - Surface (GPS)Surface texture: Profilemethod - Surfaces methodSurfaces having stratified functional properties - Part propertiesPart 2: Height characterizationusing the linear material ratio curveDIN EN 170224: 1998 Heat treatment of ferrous materia
16、lsMethods of heat treatmentPart 4: Nitriding and nitrocarburizing(available in English)3. Terminology3.1 Definitions:3.1.1 break-in, nin tribology, an initial transition process occurring in newly established wearing contacts, often accompaniedby transients in coefficient of friction or wear rate, o
17、r both, which are uncharacteristic of the given tribological systems long-termbehavior. G403.1.2 coeffcient of friction, or , nin tribology, the dimensionless ratio of the friction force (F) between two bodies to thenormal force (N) pressing these bodies together. G403.1.3 lubricant, nany material i
18、nterposed between two surfaces that reduces the friction or wear between them. D41753.1.4 lubricating grease, na semifluidsemi-fluid to solid product of a dispersion of a thickener in a liquid lubricant. D2173.1.4.1 DiscussionThe dispersion of the thickener forms a two-phase system and immobilizes t
19、he liquid lubricant by surface tension and otherphysical forces. Other ingredients are commonly included to impart special properties.3.1.5 nitro-carburization, nnitro-carburizing is not defined in the ASTM Dictionary of Engineering Science and Technology,but is defined in DIN EN 10025-1:2005.17022-
20、4:1998.3.1.6 Ra (C.L.A.), nin measuring surface finish, the arithmetic average of the absolute distances of all profile points from themean line for a given distance. Amstutz53.1.7 Rpk, nReduced peak height according to DIN EN ISO 13565-2:1998. Rpk is the mean height of the peak sticking outabove th
21、e core profile section.3.1.8 Rvk, nReduced valley height according to DIN EN ISO 13565-2:1998. Rvk is the mean depth of the valley reachinginto the material below the core profile section.3.1.9 Rz (DIN), nin measuring surface finish, the average of all Ry values (peak to valley heights) in the asses
22、sment length.Amstutz63.1.10 thickener, nin lubricating grease, a substance composed of finely divided particles dispersed in a liquid lubricant toform the products structure. D2173.1.10.1 DiscussionThe thickener can be fibers (such as various metallic soaps) or plates or spheres (such as certain non
23、-soap thickeners) which areinsoluble or, at most, only very slightly soluble in the liquid lubricant. The general requirements are that the solid particles beextremely small, uniformly dispersed, and capable of forming a relatively stable, gel-like structure with the liquid lubricant.3.2 Definitions
24、 of Terms Specific to This Standard:3.2.1 linear wear, nthe change in length of each pin prior and after tribological test.3.2.2 metal specimen, nrepresented by the lower specimen. Ball stud or ball pins are also used as common synonym.3.2.3 plastic socket, nrepresented by the upper polymeric disk s
25、pecimen. Plastic seat or beating is also used as commonsynonym.3.2.4 seizure, nlocalized fusion of metal between the rubbing surfaces of the test pieces. D57063.2.4.1 DiscussionIn this test method, seizure is indicated by a sharp rise in the coefficient of friction, over steady state, of greater tha
26、n 0.2 for over20 s. 20 s. In severe cases, a stoppage in the motor will occur (for example, see Test Method D5706).3.3 Abbreviations:5 Amstutz, Hu, “Surface Texture: The Parameters,” Bulletin MI-TP-003-0785, Sheffield Measurement Division, Warner and Swasey, 1985, p. 216 Amstutz, Hu, “Surface Textur
27、e: The Parameters”, Bulletin MI-TP-003-0785, Sheffield Measurement Division, Warner and Swasey, 1985, pp. 2931.D7420 1823.3.1 SRV, nSchwingung, Reibung, Verschlei (German); oscillating, friction, wear (English translation).4. Summary of Test Method4.1 This test method is performed on SRV test machin
28、e using a polymeric disk having three flat pins oscillating at 50 Hz againsta steel test disk with lubricant (grease) between them. Test load is fixed to 2000 N using a test temperature of 50C50 C and astroke of 1.5 mm 1.5 mm during a test time of 2 h.2 h.NOTE 1Test frequency, stroke length, tempera
29、ture, and polymeric disk and 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 and SRV II models, as they are limited to 1200 N and 1400 N, 1200 N and 1400 N, respe
30、ctively.The SRV III and SRV IV models are from the test chamber and operating conditions identical, but the SRV IV model allows to tilt and rotate the testchamber. Both are fully computer controlled. This test runs in the SRV IV and 5 models horizontally and untilted. SRV III test machines after 199
31、5 reach2000 N. 2000 N. SRV 4 and SRV 5 models can be equipped with a maximum test load unit of 2500 N.2500 N.5. Significance and Use5.1 This test method can be used to quickly determine the lubricating ability of greases lubricating automotive plastic socketsuspension joints. This test method has fo
32、und wide application in qualifying greases used in chassis systems. This test method isa material and application oriented approach based on inputs from field experiences for characterizing the tribological behavior(friction and wear) using random, discrete, and constant parameter combinations. User
33、s of this test method should determinewhether results correlate with field performance or other applications prior to commercialization.6. Apparatus6.1 SRV Test Machine,7illustrated in Figs. 1-4.7. Reagents and Materials7.1 Polymeric Test Disk with Three Pins, = 18.2+0.2-mm diameter. Each pin has a
34、diameter of = 3.0-mm (see Fig. X1.1).The plastic specimen should represent characteristic items of an inner plastic socket surface. Specimens are molded from originalsocket material; functional surfaces shall be free from scratches and any surface damages.7.2 Lower Test Disk7Vacuum arc remelted (VAR
35、) AISI 52100 steel with a inclusion rating using Method D, Type A, asseverity level number of 0.5 according to Test Methods E45 and Specification A295 or a inclusion sum value K1 10 accordingto DIN EN ISO 683-17 and spherodized annealed to obtain globular carbide, 62 6 1 HRC hardness, the surfaces o
36、f the disk beinglapped and free of lapping raw materials. The topography of the disk will be determined by four values:0.5 m 20 sCoefficient of friction, f (cut-off value for one-off increase of level): 0.358.2.3 Test parameters:Frequency: 50 HzStroke: 1.50 mmTemperature: 50 CPre-load: 50 N for 30 s
37、Test load: running in under 50 N for 30 s, then constant load of 2000 NTest duration: 120.5 minTest duration: 120 min plus 30 s from running in8.2.4 Sample rates for result-relevant measurement channels:1. Oscillation drive rod 6. Electrical Resistance Heater2. Test Ball Holder 7. Resistance Thermom
38、eter3. Load Rod 8. Test Disk Holder4. Test Ball 9. Piezoelectric Measuring Device5. Test Disk 10. Receiving BlockFIG. 2 Test Chamber Elements (Schematic) of SRV Model III Test MachineD7420 184Coefficient of friction, f: # 32 msStroke: # 2 sTest load: # 2 sFrequency: # 2 sTemperature: # 2 s.NOTE 5For
39、 SRV 5 models, it is recommended to do one sampling per period (that is, 20 ms) 20 ms) for coefficient of friction and stroke.9. Procedure9.1 Check the polymeric disk for visible damage or scratches. Clean the polymeric disk and the steel disk by wiping the surfaceswith laboratory tissue soaked with
40、 the cleaning solvent. Repeat wiping until no dark residue appears on the tissue. Immerse thesteel disk in a beaker of the cleaning solvent under ultrasonic vibration for 10 min. 10 min. Dry the steel test disk with a cleantissue to ensure no streaking occurs on the surface. Generally, a new specime
41、n should be used for each test.NOTE 6Ensure that the polymer and the constituents of the blend is resistant to the solvent. If the binder is not resistant to the solvent, wipe onlythe polymeric disk surface with a laboratory tissue.9.2 Prior to testing, determine thickness of plastic specimen in all
42、 three contact surfaces (pins) by a micrometer gauge caliperrule. Document measurement readings in the test report.9.3 Place the grease using a calibration ring while ensuring that the grease is applied to a height of 0.2-0.3 mm 0.2 mm to0.3 mm above the metal test disk.FIG. 3 SRV Model 4 Test Machi
43、neD7420 1859.4 Place the cleaned polymeric test disk in the adapter with the level side facing the adapter and the test surface with the threepins pointing upwards. Align the polymeric test disk as shown in Fig. 5.9.5 Tighten the test disk by means of the three screws at the side of the adapter. Pla
44、ce the adapter holding the polymeric testdisk on the lower disk so that the three pins are immersed in the grease.9.6 Place a 10-mm10 mm steel ball in the ring/area specimen holder and tighten it.9.7 Place a small quantity of lubricant in the recess of the adapter.9.8 Place the specimen holder conta
45、ining the ball into the recess of the adapter.9.9 Position the specimen combination comprising the ring/area holder and ball, the adapter with the polymeric disk and thelower test disk on the test platform in the test chamber. Make sure that one pin of the polymeric test disk is pointing towards the
46、operator.9.10 Insert the ring-area specimen holder in the openings of the drive axles and tighten it with knurled screws. Slightly tightenthe lower test disk by means of a clamping bow.9.11 In the SRV basic software, enter the following test parameters:Frequency = 50 HzStroke = 1.5 mmTemperature = 5
47、0 CLoad 50 N for 30 s, then increase load to 2000 N with a load ramp rate of 15 Ns 6 1 Ns.Test duration = 120 min9.12 To fully tighten the specimen combination, follow the instructions of the SRV software.10. Report10.1 During testing, friction coefficient f determined from test load Fn and friction
48、 load Ff is recorded as well as actual testingtemperature. Friction coefficient traces must be stored on data records.10.2 Report the following informationall parameters used to evaluate material follows:10.2.1 Temperature, C,1. Base of the Receiving Block 7. Upper Specimen Holder2. Piezo Force Meas
49、urement Ele-ments8. Drive Rods of the Load Unit3. Supporting Surface (HeadPlate) of the Receiving Block9. Test Disk4. Lower Specimen Holder 10. Test Ball5. Position of the Electrical Resis-tance Heating and ResistanceThermometerFn Normal Force (Test Load)6. Oscillation Drive Rods Ff Friction ForceFIG. 4 Test Chamber Elements of SRV Models 4 and 5D7420 18610.2.2 Stroke, mm,10.2.3 Frequency, Hz,10.2.4 Relative humidity,10.2.5 Brand name, type of thickener, type of base oil, and NLGI class of grease,10.2.6 Polymeric te
