1、Designation: D7918 15D7918 17Standard 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 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.1. Scope Scope*1.1 This test method
3、 covers the determination and evaluation of flow properties, wear levels, contaminants, and oxidativecondition 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 oxidat
4、ion.1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3.1 ExceptionThe exception to this will be where units of references were developed by the developers of the test equipmentand necessary to report the results of the t
5、est.1.4 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 and health practices and determine the applicability of regulatorylimitations prior to use.1.5 This inte
6、rnational standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Com
7、mittee.2. Referenced Documents2.1 ASTM Standards:2D217 Test Methods for Cone Penetration of Lubricating GreaseD4175 Terminology Relating to Petroleum Products, Liquid Fuels, and LubricantsD6595 Test Method for Determination of Wear Metals and Contaminants in Used Lubricating Oils or Used Hydraulic F
8、luids byRotating Disc Electrode Atomic Emission SpectrometryD7527 Test Method for Measurement of Antioxidant Content in Lubricating Greases by Linear Sweep VoltammetryD7546 Test Method for Determination of Moisture in New and In-Service Lubricating Oils andAdditives by Relative HumiditySensorD7718 P
9、ractice for Obtaining In-Service Samples of Lubricating GreaseD7843 Test Method for Measurement of Lubricant Generated Insoluble Color Bodies in In-Service Turbine Oils usingMembrane Patch ColorimetryE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducti
10、ng an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 active grease sampling device, ndevice designed to take an active sample of a lubricating grease from a bearing, gear,or drive shaft located in a grease lubricated component. D77181 This test m
11、ethod is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.96.07 on Integrated Testers, Instrumentation Techniques for In-Service Lubricants.Current edition approved June 1, 2015May 1, 2017. Published J
12、une 2015July 2017. Originally approved in 2015. Last previous edition approved in 2015 as D7918 15.DOI: 10.1520/D7918-15.10.1520/D7918-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume i
13、nformation, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is 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 adequatel
14、y depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current 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 Inter
15、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.1.1 DiscussionThe Grease Thief (trademarked) Type 23 is a tool which meets this description and can be used to obtain an active grease samplefrom a lubricated component. A full description and dimension
16、s of this device can be found in Annex A2.3.1.2 active sampling, vto use a sampling device to actively gather an in-service lubricating grease sample from agrease-lubricated component. D77183.1.3 calibration, nthe determination of the values of the significant parameters by comparison with values in
17、dicated by a setof reference standards. D65953.1.4 consistency, nof lubricating grease, the degree of resistance to movement under stress. D2173.1.4.1 DiscussionThe term consistency“consistency” is used somewhat synonymously with penetration.“penetration.” Generally, consistency refersto the worked
18、penetration of a grease.3.1.5 linear sweep voltammetry, na test method designed to monitor the anti-oxidant additive content in lubricating greases.D75273.1.6 lubricating grease, na semi-fluid to solid product of dispersion of a thickener in a liquid lubricant. D2173.1.6.1 DiscussionThe dispersion o
19、f the thickener forms a two-phase system and immobilizes the liquid lubricant by surface tension and otherphysical forces. Other ingredients are commonly included to impart special properties.3.1.7 in-service lubricating grease, nlubricating grease that has been applied as a lubricant to a gear, bea
20、ring, or drive screwfor any period of time. D77183.1.8 passive grease sampling device, na device designed to gather a sample from the equipment by being attached to thegrease reservoir at the purge point. D77183.1.8.1 DiscussionThe Grease Thief (trademarked) Type 13 is a tool which meets this descri
21、ption and can be used to obtain a representative greasesample from a purge path. A full description and dimensions of this device can be found in Annex A1.3.1.9 passive sampling, vto use a passive grease sampling device to collect a purged sample of in-service lubricating greasefrom a purge path. D7
22、7183.2 Definitions of Terms Specific to This Standard:3.2.1 die extrusion index, nan average of three unique test conditions of the in-service lubricating grease sample expressedas a percent when compared to the average of three unique test conditions of the unused lubricating grease baseline.3.2.2
23、die extrusion tester, na device that measures the consistency of in-service lubricating greases and compares themeasurement to the values obtained from a baseline sample of lubricating grease.3.2.3 ferrous debris level, nthe total amount of ferrous metal as measured by a Hall-effect sensor in the gr
24、ease sampleindependent of particle size.3.2.4 full attenuation, nthe loss of intensity in signal strength.3.2.5 grease colorimetry, nthe science of color measurement by the evaluation of the CIE LAB values of grease in the visiblelight region of the electromagnetic spectrum.3.2.6 grease ribbon, ngre
25、ase that is extruded onto a substrate.3.2.7 indexing die, na single-use orifice die to measure the consistency as compared to the baseline.3.2.8 spring cell calibration cylinder, na cylinder that houses a spring and a push rod to compress the spring.3.2.9 substrate, nthe single-use strip onto which
26、a ribbon of grease is extruded.3 The 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 analternative(s) to this patented item to the ASTM International Headquarters. Your comments will receive c
27、areful consideration at a meeting of the responsible technicalcommittee, which you may attend. The sole source of the Grease Thief Type I and Type II are known to the committee is York Laboratories, LLC located at 410 Kings MillRd., York, PA 17401. If you are aware of alternative suppliers, please p
28、rovide this information to ASTM International Headquarters. Your comments will receive carefulconsideration at a meeting of the responsible technical committee,1 which you may attend.D7918 1723.2.10 substrate segment, na peel-away section of the substrate containing a portion of the extruded grease;
29、 the segments arepre-cut to hold 0.25 g of extruded grease ribbon.3.2.11 speed 1, nthe slowest speed in which the grease is extruded from the indexing die.3.2.12 speed 2, nthe fastest speed in which the grease is extruded from the indexing die.3.2.13 speed 3, nthe intermediate speed at which the gre
30、ase is extruded from the indexing die.4. Summary of Test Method4.1 Testing of a grease sample includes steps that characterize the ferrous wear within the sample, the consistency of the sample,and properties related to its chemistry.4.2 A grease sample of known volume is measured to determine the de
31、nsity of ferrous material in the sample.4.3 Agrease sample held with a defined geometry sample holder is placed into a temperature-controlled instrument and extrudedonto a substrate as a thin ribbon or strip of grease. The extrusion process provides a measurement of the consistency of the grease.4.4
32、 The test method requires the grease to be tested at three different rates to reflect the non-Newtonian nature of greases.Testing at several different rates creates a series of step changes that are then compared to an unused baseline grease that has alsobeen tested under the same conditions.4.5 Whi
33、le the flow properties are being measured, the grease is simultaneously deposited onto a thin-film substrate containingsubstrate segments. Each substrate segment contains approximately 0.25 g of grease. The individual substrate segments are usedfor further testing of wear, contamination, and oxidati
34、ve properties.4.6 The substrate is removed from the instrument and processed further to obtain information related to the chemistry andcontent of the grease sample including linear sweep voltammetry and grease colorimetry.5. Significance and Use5.1 Trending the wear, contamination, consistency, and
35、oxidative properties of a lubricating grease areis a crucial part ofcondition monitoring condition-monitoring programs. Changes in these properties or deviations from the new grease can beindicative of problems within the lubricated component, such as the mixing of incompatible thickener types, exce
36、ssive wear orcontaminant levels, or significant depletion of antioxidant levels. These test methods also makes it possible to develop trends thatcan be used to predict failures before they occur and allow for corrective action to be taken.6. Interferences6.1 Particulate MatterWhen the in-service gre
37、ase sample is heavily contaminated with particulate matter, it may be necessaryto perform a dilution of the sample in order to properly extrude the sample onto the substrate. Larger pieces of particulate mattermay also cause spikes in the load profile graph. The data from these spikes should be disc
38、ounted from the average forcecalculations because they are not indicative of changes in the flow properties of the sample.6.1.1 Heavily contaminated grease samples are considered any grease that contains solid particulate of size or quantity thatresults in clogging of the die, which inhibits the com
39、pletion of the test.NOTE 1The specific steps to perform a dilution of grease samples is not addressed in this test method.6.2 Sample SizeThe passive sampling device shall be at least 70 % filled to perform the testing indicated within this testmethod. If the sampling device is insufficiently filled,
40、 the instrument may not record a force reading over the entirety of theprogram.6.3 ColorThe grease colorimetry test may become insignificant if the color of the grease causes full attenuation and minimaltransmittance of the signal making it incomparable to the new grease.7. Apparatus7.1 Passive Grea
41、se Sampling DeviceThe device that holds the grease sample. The device is typically capable of holdingapproximately 1.5 g to 2 g of grease when full. A full description and dimensions of this device can be found in Annex A1.7.2 Active Grease Sampling DeviceThe device that holds an active grease sampl
42、e from a grease lubricated grease-lubricatedcomponent. A full description and dimensions of this device can be found in Annex A2.7.3 Die Extrusion Tester4Designed for the passive grease sampling device, the die extrusion tester is a temperature-controlledchamber consisting of a table that is control
43、led by a linear actuator that holds the substrate, a bracket that holds the passive greasesampling device, and a second linear actuator to push the handle of the passive grease sampling device. Both the passive grease4 Wurzbach, R. and Williams, L., “Die Extrusion Method For Comparing Changes in Gre
44、ase Consistency and Flow Characteristics,” Viscosity and Rheology of In-ServiceFluids as They Pertain to Condition Monitoring, ASTM STP 1564, 2013, ASTM International.D7918 173sampling device and the second linear actuator are mounted perpendicular to the substrate table. A load cell is mounted betw
45、eenthe second actuator and the handle of the passive grease sampling device to measure the force during the extrusion. The dieextrusion tester is shown in Fig. 1.7.4 Constant Temperature ChamberThe test specimens in the passive grease sampling device should be heated in thetemperature-controlled cha
46、mber of the die extrusion tester prior to performing any test. The passive grease sampling device shallhave the indexing die firmly engaged on the threaded open end of the device.7.5 Ferrous Debris AnalyzerAn analyzer that allows the passive grease sampling device to be inserted completely in the co
47、ilgeometry, designed to measure the total amount of ferrous debris in the grease sample. By use of a Hall-effect sensor, the totalamount of ferrous debris is designed to measure quantitatively in parts per million (ppm). Upon receipt of the sample, it is the firsttest performed on the grease.7.6 Lin
48、ear Sweep VoltammetryLinear sweep voltammetry measures the amount of hindered phenols, amines, and zinc dithiodialkyl phosphate (ZDDP) in a lubricating grease. Using 0.25 g of grease from the substrate, one substrate segment is inserted intoa vial and the antioxidant concentration remaining in the g
49、rease is measured and compared to an unused sample of the same grease.7.7 Grease ColorimetryThe grease colorimetry test provides a spectrum in the 400 nm to 700 nm region of the visible lightspectrum.An optical spectroscopy cell is used and the substrate segment is placed into the same holder. The delta-E values withinthe CIE LAB scale are recorded and a spectrum can be generated in a method similar to Test Method D7843.7.8 Direct Imaging SystemA particle sizing and identification component consisting of a CCD (charge-coupled device) videoc
