1、Designation: D7918 17aStandard 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 desi
2、gnation 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. Scope*1.1 This test method covers the d
3、etermination 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 Th
4、e values 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
5、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, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This
6、 international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (
7、TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D217 Test Methods for Cone Penetration of LubricatingGreaseD6595 Test Method for Determination of Wear Metals andContaminants in Used Lubricating Oils or Used HydraulicFluids by Rotating Disc Electrode Atomic Emission Spec-trometryD7527 Test
8、Method for Measurement of Antioxidant Con-tent in Lubricating Greases by Linear Sweep VoltammetryD7546 Test Method for Determination of Moisture in Newand In-Service Lubricating Oils and Additives by RelativeHumidity SensorD7718 Practice for Obtaining In-Service Samples of Lubri-cating GreaseD7843 T
9、est Method for Measurement of Lubricant Gener-ated Insoluble Color Bodies in In-Service Turbine 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 Metho
10、d3. Terminology3.1 Definitions:3.1.1 active grease sampling device, ndevice designed totake an 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 des
11、cription and can be used toobtain an active grease sample from a lubricated component. Afull description and dimensions of this device can be found inAnnex A2.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct respon
12、sibility ofSubcommittee D02.96.07 on Integrated Testers, Instrumentation Techniques forIn-Service Lubricants.Current edition approved Nov. 15, 2017. Published December 2017. Originallyapproved in 2015. Last previous edition approved in 2017 as D7918 17. DOI:10.1520/D7918-17A.2For referenced ASTM sta
13、ndards, 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.3The Grease Thief Type I and Type II is described in US Patent No. 7984661.Interested
14、 parties are invited to submit information regarding the identification of analternative(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 G
15、rease ThiefType I and Type II are known to the committee is York Laboratories, LLC 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 meetin
16、g of the responsible technicalcommittee,1which you may attend.*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 international standard was developed in accordance with
17、 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) Committee.13.1.2 active sampling, vto use a sampling
18、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 comparison with values indicated bya set of reference standards. D65953.1.4 consistency, nof lubricating grease
19、, the degree ofresistance to movement under stress. D2173.1.4.1 DiscussionThe term “consistency” is used some-what synonymously with “penetration.” Generally, consistencyrefers to the worked penetration of a grease.3.1.5 linear sweep voltammetry, na test method designedto monitor the anti-oxidant ad
20、ditive 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 bysurface tension and other physic
21、al 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 device, na device designedto gather
22、 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 fulldescription and dimensions of
23、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 average of three unique testconditi
24、ons 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 greases and compares themeasurem
25、ent 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 signalstrength.3.2.5 grease colo
26、rimetry, 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 measure theconsistency as compared t
27、o 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 containing a portion of the extr
28、uded 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 3, nthe intermediate speed at whi
29、ch 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 known volume is measured todetermi
30、ne 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 measurement of the consistencyof the gre
31、ase.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 tested under the same conditions.4.
32、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 testing of wear, contamination, an
33、doxidative 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 wear, contamination, consistency
34、, andoxidative properties of a lubricating grease is 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 thickener types, excessive wear or contami
35、nantlevels, 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.D7918 17a26. Interferences6.1 Particulate MatterWhen the in-service grease sampleis
36、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 be discounted fromthe a
37、verage force calculations because they are not indicativeof changes in the flow properties of the sample.6.1.1 Heavily contaminated grease samples are consideredany grease that contains solid particulate of size or quantity thatresults in clogging of the die, which inhibits the completion ofthe test
38、.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 insufficiently filled, theinstrument may no
39、t 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 Passive Grease Sampling DeviceThe
40、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 sample from a grease-lubricated com
41、ponent.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 actuator that holds the substrate,
42、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 cell is mounted between the secon
43、d 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 thetemperature-controlled chamber of the die
44、 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 completely in thecoil geometry, design
45、ed 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 grease.7.6 Linear Sweep Voltamme
46、tryLinear 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 remainingin the grease is measured and
47、 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 holder. The delta-Evalues within t
48、he CIE LAB scale are recorded and a spectrumcan be generated in a method similar to Test Method D7843.7.8 Direct Imaging SystemA particle sizing and identifi-cation component consisting of a CCD (charge-coupled de-vice) video chip, pulsed diode backlight, magnifying lens, finefocus dial, software, a
49、nd readout system.4Wurzbach, 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 Tester4D7918 17a37.9 Relative Humidity Sensor AnalyzerThe test specimensin the passive grease sampling device are extruded on thesubstrate of the die extrusion tester, to create an approximate0.25 g thin-film deposition on a plastic substrate. One plasticsubstr
