1、Designation: F2661 07 (Reapproved 2015)Standard Test Method forDetermining the Tribological Behavior and the RelativeLifetime of a Fluid Lubricant using the Spiral OrbitTribometer1This standard is issued under the fixed designation F2661; the number immediately following the designation indicates th
2、e 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 quantitative determina
3、tionof the friction coefficient and the lifetime of oils and greases,when tested on a standard specimen under specified conditionsof preparation, speed, Hertzian stress, materials, temperature,and atmosphere, by means of the Spiral Orbit Tribometer(SOT). This test method is intended primarily as an
4、evaluationof the lifetimes of fluid lubricants under vacuum and ambientconditions.1.2 This standard may involve hazardous materials,operations, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of
5、this standard toestablish appropriate safety and health practices and todetermine the applicability of regulatory limitations prior touse.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterF22 Test Method for Hydrophobic Surface Films by theWater-Break TestF2215 Specific
6、ation for Balls, Bearings, Ferrous and Non-ferrous for Use in Bearings, Valves, and Bearing Appli-cationsG115 Guide for Measuring and Reporting Friction Coeffi-cients2.2 Anti Friction Bearing Manufacturers Association Stan-dards3ANSI ABMA ISO 3290 (AFBMA Standard 10 Balls)3. Terminology3.1 Definitio
7、ns:3.1.1 coeffcient of frictionthe dimensionless ratio of thefriction force between two bodies to the normal force pressingthese bodies together.3.1.2 fixed platestationary, horizontal flat plate, typicallythrough which a force (the “load”) is applied to the ball.3.1.3 friction coeffcient limitmaxim
8、um value that thefriction coefficient is permitted to attain.3.1.4 guide platephysical element that deflects the ball toits original orbit radius.3.1.5 lubricant total amount mass of lubricant depositedon the entire ball surface at the beginning of the test.3.1.6 normalized lifetimenumber of ball or
9、bits performeduntil the friction coefficient limit is reached divided by thelubricant total amount initially deposited on the ball.3.1.7 rotary plateflat plate rotating at a constant rateselected for the test.3.1.8 scrub zoneRegion of the balls orbit in which theball is in contact with the guide pla
10、te.3.1.9 spiral orbittrack traced by the ball on the fixed androtating plates of the Spiral Orbit Tribometer. The track has aspiral shape.4. Summary of Test Method4.1 Alubricated ball is clamped between two parallel plates.One of the plates rotates up to 210 rpm, causing the ball to rollin a near-ci
11、rcular orbit, but is actually an opening spiral. Aclamping force, the “load”, provides a chosen mean Hertzstress (typically 1.5 GPa). The system is targeted to operate inthe boundary lubrication regime due to the combination of thehigh load, the moderate speed, and the small amount oflubricant (appr
12、oximately 50 g). The ball rolls and pivots in aspiral orbit and is maintained in the orbit by the guide plate.The ball slides on the rotating plate when it contacts the guideplate. The measured force exerted by the ball on the guide plateis used to determine the friction coefficient. The tribometerr
13、uns until the coefficient of friction rises to values much largerthan the initial, steady value. At this point the initial charge of1This test method is under the jurisdiction of ASTM CommitteeF34 on RollingElement Bearings and is the direct responsibility of Subcommittee F34.02 onTribology.Current
14、edition approved April 1, 2015. Published July 2015. Originallyapproved in 2007. Last previous edition approved in 2007 as F266107. DOI:10.1520/F2661-07R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AST
15、MStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Bearing Manufacturers Association (ABMA), 8221Old Courthouse Road, Suite 207 Vienna, Virginia 22182.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc
16、ken, PA 19428-2959. United States1lubricant has been depleted by tribodegradation and the systemis running virtually unlubricated. The normalized lifetime isobtained from the number of spiral orbits completed beforereaching the chosen friction coefficient limit divided by thetotal lubricant mass on
17、the ball at the beginning of the test. Aminimum of four tests per lubricant and test condition shall beperformed. Lubricants can be compared by calculating theiraverage normalized lifetimes for a given set of test conditions.5. Significance and Use5.1 Relevance of the Spiral Orbit Tribometer (SOT)Th
18、eSOT was designed to evaluate the relative degradation rates ofliquid lubricants in a contact environment similar to that in anangular contact bearing operating in the boundary lubricationregime. It functions as a screening device to quickly select thelubricants, evaluate the ability of various comp
19、onents of alubricant (base oil, thickener, or additive) to lubricate a contactin rolling, pivoting, and sliding conditions simultaneously, andstudy their chemical decomposition if necessary. The SOTprovides a means to study the tribological behavior of oils andgreases during operation, while they un
20、dergo changes as afunction of typical parameters encountered in the lubricationfield (temperature, environment, materials used, load applied,and speed). Test conclusion is defined to be when a frictioncoefficient limit (typically an increase of 0.1 above the steadystate value) is surpassed. Normaliz
21、ed lubricant lifetime is thendefined as the number of orbits completed divided by the initialamount of lubricant used (in g). The SOT was initiallydeveloped to evaluate lubricants for space applications, but isalso relevant for conventional environments. Some results invacuum are presented (Fig. 1).
22、 At this time, no data for tests inambient conditions have been published (see Fig. 2). The userof this test method should determine to their own satisfactionwhether results of this test procedure correlate with fieldperformance or other bench test procedures.6. Apparatus6.1 The Spiral Orbit Tribome
23、ter (SOT)See Fig. 3.6.1.1 General descriptionFig. 3 shows a schematic draw-ing of a typical SOT. The system consists of a lubricated ballrolling and pivoting between a fixed plate and a rotary plate.The load is applied through the fixed plate. The track is a spiraland the ball is returned to its ori
24、ginal orbit radius by contactingthe guide plate, which forces the ball to return to its originalradius each orbit. The friction coefficient is determined by themeasuring the force on the guide plate when the ball contactsthe guide plate. A piezoelectric force transducer is attached tothe guide plate
25、. This force, divided by twice the normal load,is the friction coefficient.6.1.2 Motor drive A variable speed motor, capable ofconstant speed, is required. Rotating plate speeds are typicallyin the range 1 to 210 rpm (0.10 to 22 rad.s1). The effectivestiffness of the axis shall be at least 1.8 E +05
26、 Newton/meteraxial in the load direction, 3.6 E +08 Newton/meter radial and1.13 E +05 Newton-meter/Radian moment. The TIR of themotor shaft shall be 0.0254 millimeters maximum.6.1.3 Fixed load plate The load plate shall have an axialstiffness of at least 1.8 E +08 Newton/meter in the loaddirection.
27、The effective radial stiffness of the plate axis shall beat least1.8 E+08 Newton/meter and the moment stiffness shallbe at least 1.13 E +05 Newton-meter/Radian.6.1.4 Orbit counter The SOT shall be equipped with arevolution counter or its equivalent that will record the numberof ball orbits. The trib
28、ometer would preferably have the abilityto shut off after a pre-selected number of orbits or frictioncoefficient has been reached.6.1.5 Applied load The fixed plate is attached to a systemto apply the load, up to 222.5 N (50 lb.), providing the desiredHertzian stress, typically 1.5 GPa.6.1.6 The ins
29、truments and gauges:6.1.6.1 Friction force The friction coefficient is deter-mined by measuring the force on the guide plate while the ballcontacts the guide plate. This force is measured using apiezoelectric force transducer and a charge amplifier. Thefriction force and the coefficient of friction
30、can then bePepper, S.V., Kingsbury, E.P., “Spiral Orbit Tribometry Part II: Evaluation of Three Liquid Lubricants in Vacuum”, Tribo. Trans., V 46, 1, pp 65-69, 2003FIG. 1 Relative lifetimes of three typical space lubricants at 23C in vacuum on 52100 steelF2661 07 (2015)2obtained as explained in Sect
31、ion 11. The load cell shall belinear to within 2 % across the entire temperature range of thetest.6.1.6.2 Environment The SOT operates in either oneatmosphere air, under a cover gas, or vacuum. When operatingunder vacuum or ultrahigh vacuum, a cold cathode pressuregauge attached to the chamber monit
32、ors the pressure. A hotcathode gauge should be avoided since electrons from thefilament could alter lubricant chemistry. It is the responsibilityof the user to determine the chemical purity of the environmentand gas to establish the contribution to tribochemistry.6.1.6.3 Measurement of the temperatu
33、re When a con-trolled temperature is required, the temperature is monitoredusing a thermocouple (for example, K-type) attached to thestationary disk during the test.7. Reagents and Materials7.1 Balls, plates, guide plates. Typical instrument bearingmaterials may be of 440C material, but other materi
34、als may beused to simulate the bearing application.7.1.1 Test ballsTest balls shall be 12.7 mm (0.5 inch)diameter, grade 25 or better, made with 440C stainless steel.Bazinet, D.G., Espinosa, M.A., Loewenthal, S.H., Gschwender, L., Jones, W.R., Jr., Predmore, R.E., “Life of Scanner Bearings with Four
35、 Space Liquid Lubricants”, Proc.37thAerospace Mech. Symp., Johnson Space Center, May 19-21, 2004FIG. 2 Comparison between full scale bearing tests* and SOT data at 23C on 440C steel.FIG. 3 Detail of the Spiral Orbit TribometerF2661 07 (2015)3Their recommended Rockwell hardness shall be 58 to 62. See
36、Specification F2215 or ANSI ABMA ISO 3290 (AFBMAStandard 10) for ball specification reference. Other materialsmay be used to simulate specific application chemistry.7.1.2 Plates, Guide platesThe fixed plate and the rotaryplate are disks of 50.8 mm (2 inch) in diameter, may be madewith 440C stainless
37、 steel, or any desired material. Surfaceroughness of 0.05 mm average roughness or less is recom-mended. The guide plates are small cylinders 12.7 mm (0.5inch in diameter), with a polished surface of 0.05 mm averageroughness or less (recommended). The recommended Rock-well hardness for 440C shall be
38、58 to 62. Stationary and rotaryplates should be made with the same material. Any bearingmaterial can be used, depending on the application beingsimulated. The recommended values should be used unlessdifferences are required to simulate a specific application.7.1.3 Care must be taken in surface prepa
39、ration and han-dling to avoid surface damage or contamination after cleaningthat alters the material. Typical cleaning methods may be usedwhen the results will pass an Test Method F22 standard test forwetability and do not damage the materials or adversely alterthe sample surfaces. A wettability tes
40、t using the intendedlubricant to evaluate the ball and plate cleaning method isrecommended.7.1.4 Reagent grade chemicals shall be used per TestMethod F22 section 8.1. It is the users responsibility toprevent contamination or adulteration of the lubricant samples,and prevent materials used to clean o
41、r lubricate from harmingthe samples.8. Hazards8.1 Use of solvents Operator will refer to the safety datasheet of all the solvents used and will take appropriateprecautions.8.2 Use of ultrasonic cleaning systems (if applicable)Operator will refer to the instruction manual of the ultrasonicbath before
42、 use.8.3 Use of ultra violet (U.V.)/ozone cleaning system (ifapplicable)Operator will refer to the instruction manual ofthe U.V./ozone cleaning system before use. Special care will betaken to check the compatibility of the materials used to a U.V.and ozone exposure.8.4 Ultrahigh vacuum chamber (if a
43、pplicable)Thevacuum chamber will be operated with appropriate copper orelastomer seals to reach ultrahigh vacuum, and will not beopened until the inside of the chamber has reached atmosphericpressure.9. Sampling, Test Specimens, and Test Units9.1 Test specimens Specimens (plates, balls, guide plates
44、)will be kept for further analysis, if required.9.2 Test unitsOnly SI units will be used.10. Procedure10.1 Cleaning of the parts and tools may be any method thatsimulates the application. It is recommended that the results ofcleaning procedures are tested using a water break free testsuch as Test Me
45、thod F22 using reagent grade water perSpecification D1193, or a wettability test using the intendedoil. Since many variations of cleaning methods exist and theirresults may have a strong effect on the results, it is the usersresponsibility to determine the effectiveness and safety of thecleaning met
46、hods. The details of the cleaning methods shalldescribed in the test report.10.2 Lubrication of the ballsLubrication of the test systemis to the ball only. The objective is to lubricate the balls with asmall and controlled amount of lubricant. The target amount isas close as possible to 50 +/ 2 g fo
47、r a 12.7 mm diameter ball.10.2.1 Lubrication of the balls with oil:10.2.1.1 Preparation of a dilute solution of oil:(1) Choose a solvent suitable for the oil to be tested. Theuser must determine that the solvent does not harm the samplesurface or alter the lubricant.(2) Weigh a clean, dry and empty
48、bottle.(3) Put a small drop of oil within the bottle.(4) Note the mass of oil (moil) in milligrams.(5) Add a volume of solvent in the bottle to obtain theproportion of one milliliter of solvent per one milligram of oil.(6) Close the bottle and shake it to create an homogeneoussolution.It is the resp
49、onsibility of the user to determine the type ofsolvent used. Some solvents may not produce a homogeneoussolution and can have an adverse effect on the results. Caremust be taken to produce a final lubricant film that isunadulterated on the ball.10.2.1.2 Lubrication of the ball:(1) Weigh a dry, clean ball with a micro-balance to 62 g.(2) Fill a micro-syringe with the dilute oil solution.(3) Attach the ball to a handling tool that spins the ball andstart the ball spinning.(4) Put fifty microliters, drop by drop, of the dilute solutionon the
