1、Designation: D7918 15Standard Test Method forMeasurement of Flow Properties and Evaluation of Wear,Contaminants and Oxidative Properties of LubricatingGrease by Die Extrusion Method and Preparation1This standard is issued under the fixed designation D7918; the number immediately following the design
2、ation 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.1. Scope1.1 This test method covers the dete
3、rmination and evalua-tion of flow properties, wear levels, contaminants, and oxida-tive condition of new and in-service lubricating grease.1.2 This test method provides guidance on evaluating in-service grease samples, NLGI grades 00 to 3, for wear,consistency, contamination, and oxidation.1.3 The v
4、alues stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3.1 ExceptionThe exception to this will be where unitsof references were developed by the developers of the testequipment and necessary to report the results of the test.1.4 This sta
5、ndard 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 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1
6、ASTM Standards:2D217 Test Methods for Cone Penetration of LubricatingGreaseD4175 Terminology Relating to Petroleum, PetroleumProducts, and LubricantsD6595 Test Method for Determination of Wear Metals andContaminants in Used Lubricating Oils or Used HydraulicFluids by Rotating Disc Electrode Atomic E
7、mission Spec-trometryD7527 Test Method for Measurement of Antioxidant Con-tent in Lubricating Greases by Linear Sweep VoltammetryD7718 Practice for Obtaining In-Service Samples of Lubri-cating GreaseD7843 Test Method for Measurement of Lubricant Gener-ated Insoluble Color Bodies in In-Service Turbin
8、e Oilsusing Membrane Patch ColorimetryE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 active grease sampling device, ndevice designed totake an
9、 active sample of a lubricating grease from a bearing,gear, or drive shaft located in a grease lubricated component.D77183.1.1.1 DiscussionThe Grease Thief (trademarked) Type23is a tool which meets this description and can be used toobtain an active grease sample from a lubricated component. Afull d
10、escription and dimensions of this device can be found inAnnex A2.3.1.2 active sampling, vto use a sampling device toactively gather an in-service lubricating grease sample from agrease-lubricated component. D77183.1.3 calibration, nthe determination of the values of thesignificant parameters by comp
11、arison with values indicated bya set of reference standards. D65953.1.4 consistency, nof lubricating grease, the degree ofresistance to movement under stress. D2171This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct re
12、sponsibility ofSubcommittee D02.96.07 on Integrated Testers, Instrumentation Techniques forIn-Service Lubricants.Current edition approved June 1, 2015. Published June 2015. DOI: 10.1520/D7918-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
13、serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The Grease Thief Type I and Type II is described in US Patent No. 7984661.Interested parties are invited to submit information regarding the identification of analte
14、rnative(s) to this patented item to the ASTM International Headquarters. Yourcomments will receive careful consideration at a meeting of the responsibletechnical committee, which you may attend. The sole source of the Grease ThiefType I and Type II are known to the committee is York Laboratories, LL
15、C locatedat 410 Kings Mill Rd., York, PA 17401. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.Copyright ASTM Inte
16、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.4.1 DiscussionThe term consistency is used somewhatsynonymously with penetration. Generally, consistency refersto the worked penetration of a grease.3.1.5 linear sweep voltammetry, na test method desig
17、nedto monitor the anti-oxidant additive content in lubricatinggreases. D75273.1.6 lubricating grease, na semi-fluid to solid product ofdispersion of a thickener in a liquid lubricant. D2173.1.6.1 DiscussionThe dispersion of the thickener forms atwo-phase system and immobilizes the liquid lubricant b
18、ysurface tension and other physical forces. Other ingredients arecommonly included to impart special properties.3.1.7 in-service lubricating grease, nlubricating greasethat has been applied as a lubricant to a gear, bearing, or drivescrew for any period of time. D77183.1.8 passive grease sampling de
19、vice, na device designedto gather a sample from the equipment by being attached to thegrease reservoir at the purge point. D77183.1.8.1 DiscussionThe Grease Thief (trademarked) Type13is a tool which meets this description and can be used toobtain a representative grease sample from a purge path. A f
20、ulldescription and dimensions of this device can be found inAnnex A1.3.1.9 passive sampling, vto use a passive grease samplingdevice to collect a purged sample of in-service lubricatinggrease from a purge path. D77183.2 Definitions of Terms Specific to This Standard:3.2.1 die extrusion index, nan av
21、erage of three unique testconditions of the in-service lubricating grease sample ex-pressed as a percent when compared to the average of threeunique test conditions of the unused lubricating grease base-line.3.2.2 die extrusion tester, na device that measures theconsistency of in-service lubricating
22、 greases and compares themeasurement to the values obtained from a baseline sample oflubricating grease.3.2.3 ferrous debris level, nthe total amount of ferrousmetal as measured by a Hall-effect sensor in the grease sampleindependent of particle size.3.2.4 full attenuation, nthe loss of intensity in
23、 signalstrength.3.2.5 grease colorimetry, nthe science of color measure-ment by the evaluation of the CIE LAB values of grease in thevisible light region of the electromagnetic spectrum.3.2.6 grease ribbon, ngrease that is extruded onto asubstrate.3.2.7 indexing die, na single-use orifice die to mea
24、sure theconsistency as compared to the baseline.3.2.8 spring cell calibration cylinder, na cylinder thathouses a spring and a push rod to compress the spring.3.2.9 substrate, nthe single-use strip onto which a ribbonof grease is extruded.3.2.10 substrate segment, na peel-away section of thesubstrate
25、 containing a portion of the extruded grease; thesegments are pre-cut to hold 0.25 g of extruded grease ribbon.3.2.11 speed 1, nthe slowest speed in which the grease isextruded from the indexing die.3.2.12 speed 2, nthe fastest speed in which the grease isextruded from the indexing die.3.2.13 speed
26、3, nthe intermediate speed at which thegrease is extruded from the indexing die.4. Summary of Test Method4.1 Testing of a grease sample includes steps that charac-terize the ferrous wear within the sample, the consistency ofthe sample, and properties related to its chemistry.4.2 A grease sample of k
27、nown volume is measured todetermine the density of ferrous material in the sample.4.3 A grease sample held with a defined geometry sampleholder is placed into a temperature-controlled instrument andextruded onto a substrate as a thin ribbon or strip of grease. Theextrusion process provides a measure
28、ment of the consistencyof the grease.4.4 The test method requires the grease to be tested at threedifferent rates to reflect the non-Newtonian nature of greases.Testing at several different rates creates a series of step changesthat are then compared to an unused baseline grease that hasalso been te
29、sted under the same conditions.4.5 While the flow properties are being measured, the greaseis simultaneously deposited onto a thin-film substrate contain-ing substrate segments. Each substrate segment contains ap-proximately 0.25 g of grease. The individual substrate seg-ments are used for further t
30、esting of wear, contamination, andoxidative properties.4.6 The substrate is removed from the instrument andprocessed further to obtain information related to the chemistryand content of the grease sample including linear sweepvoltammetry and grease colorimetry.5. Significance and Use5.1 Trending the
31、 wear, contamination, consistency, andoxidative properties of a lubricating grease are a crucial part ofcondition monitoring programs. Changes in these properties ordeviations from the new grease can be indicative of problemswithin the lubricated component, such as the mixing ofincompatible thickene
32、r types, excessive wear or contaminantlevels, or significant depletion of antioxidant levels. These testmethods also makes it possible to develop trends that can beused to predict failures before they occur and allow forcorrective action to be taken.6. Interferences6.1 Particulate MatterWhen the in-
33、service grease sampleis heavily contaminated with particulate matter, it may benecessary to perform a dilution of the sample in order toproperly extrude the sample onto the substrate. Larger pieces ofparticulate matter may also cause spikes in the load profilegraph. The data from these spikes should
34、 be discounted fromthe average force calculations because they are not indicativeof changes in the flow properties of the sample.D7918 1526.1.1 Heavily contaminated grease samples are consideredany grease that contains solid particulate of size or quantity thatresults in clogging of the die, which i
35、nhibits the completion ofthe test.NOTE 1The specific steps to perform a dilution of grease samples isnot addressed in this test method.6.2 Sample SizeThe passive sampling device shall be atleast 70 % filled to perform the testing indicated within this testmethod. If the sampling device is insufficie
36、ntly filled, theinstrument may not record a force reading over the entirety ofthe program.6.3 ColorThe grease colorimetry test may become insig-nificant if the color of the grease causes full attenuation andminimal transmittance of the signal making it incomparable tothe new grease.7. Apparatus7.1 P
37、assive Grease Sampling DeviceThe device that holdsthe grease sample. The device is typically capable of holdingapproximately 1.5 g to2gofgrease when full. A fulldescription and dimensions of this device can be found inAnnex A1.7.2 Active Grease Sampling DeviceThe device that holdsan active grease sa
38、mple from a grease lubricated component.Afull description and dimensions of this device can be found inAnnex A2.7.3 Die Extrusion Tester4Designed for the passive greasesampling device, the die extrusion tester is a temperature-controlled chamber consisting of a table that is controlled by alinear ac
39、tuator that holds the substrate, a bracket that holds thepassive grease sampling device, and a second linear actuator topush the handle of the passive grease sampling device. Boththe passive grease sampling device and the second linearactuator are mounted perpendicular to the substrate table. Aload
40、cell is mounted between the second actuator and thehandle of the passive grease sampling device to measure theforce during the extrusion. The die extrusion tester is shown inFig. 1.7.4 Constant Temperature ChamberThe test specimens inthe passive grease sampling device should be heated in thetemperat
41、ure-controlled chamber of the die extrusion testerprior to performing any test. The passive grease samplingdevice shall have the indexing die firmly engaged on thethreaded open end of the device.7.5 Ferrous Debris AnalyzerAn analyzer that allows thepassive grease sampling device to be inserted compl
42、etely in thecoil geometry, designed to measure the total amount of ferrousdebris in the grease sample. By use of a Hall-effect sensor, thetotal amount of ferrous debris is designed to measure quanti-tatively in parts per million (ppm). Upon receipt of the sample,it is the first test performed on the
43、 grease.7.6 Linear Sweep VoltammetryLinear sweep voltammetrymeasures the amount of hindered phenols, amines and zincdithio dialkyl phosphate (ZDDP) in a lubricating grease. Using0.25 g of grease from the substrate, one substrate segment isinserted into a vial and the antioxidant concentration remain
44、ingin the grease is measured and compared to an unused sample ofthe same grease.7.7 Grease ColorimetryThe grease colorimetry test pro-vides a spectrum in the 400 nm to 700 nm region of the visiblelight spectrum. An optical spectroscopy cell is used and thesubstrate segment is placed into the same ho
45、lder. The delta-Evalues within the CIE LAB scale are recorded and a spectrumcan be generated in a method similar to Test Method D7843.8. Reagents and Materials8.1 Spring Cell Calibration CylinderThis device is usedto perform a calibration check on the die extrusion tester priorto use. See Annex A3 f
46、or the full calibration procedure.8.2 Indexing DieThreads onto the end of the passivegrease sampling device prior to performing the die extrusiontest.8.3 SubstrateThe three-layered plastic substrate shall belong enough to hold the grease ribbon once it is extruded fromthe indexing die. The substrate
47、s three layers consist of a rigid4Wurzbach, R. and Williams, L., “Die Extrusion Method For ComparingChanges in Grease Consistency and Flow Characteristics,” Viscosity and Rheologyof In-Service Fluids as They Pertain to Condition Monitoring, ASTM STP 1564,2013, ASTM International.FIG. 1 Die Extrusion
48、 Tester4D7918 153bottom layer of high-density polyethylene, a double-sidedreleasable adhesive, and a top layer of low-density polyethyl-ene. The top layer of the substrate is divided into peel-awaysegments that, when fully covered with the grease ribbon, eachcontains approximately 0.25 g of grease.9
49、. Sampling9.1 Good grease sampling procedures are critical to goodanalyses and samples should be taken in accordance withPractice D7718.10. Preparation of Test Specimen10.1 Ferrous Debris AnalyzerPrior to analysis, the pas-sive grease sampling tool shall be removed from the storagecontainer. The passive grease sampling tool shall be placed intothe ferrous debris analyzer to determine the total amount offerrous wear present (in ppm).10.2 Passive Grease Sampling ToolUpon completion ofthe ferrous debris analyzer test, the protective cap shall
