1、Designation: D1478 11Standard Test Method forLow-Temperature Torque of Ball Bearing Grease1This standard is issued under the fixed designation D1478; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the determination of the extentto
3、which a grease retards the rotation of a slow-speed ballbearing by measuring starting and running torques at lowtemperatures (below 20C (0F).1.1.1 Torque measurements are limited by the capacity ofthe torque-measuring equipment.NOTE 1When initially developed, the original dynamometer scalelimited th
4、e torque capacity to approximately 30 000 gcm; the originaldynamometer scale is obsolete, however. The suggested replacement scalehas not been evaluated; it could extend the limit to approximately 75 000gcm.1.2 The values stated in SI units are to be regarded asstandard. The values given in parenthe
5、ses are for informationonly. The exception is torque values that are given in cgs-metric units, which are universally used in grease specifica-tions.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this s
6、tandard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardand warning statements, see 6.1.1, 7.2, 7.4, 8.7, and 8.11.2. Referenced Documents2.1 ASTM Standards:2D4693 Test Method for Low-Temperature Torque
7、 ofGrease-Lubricated Wheel Bearings2.2 ANSI/AFBMA Standard:Standard 20-1987 Radial Bearings of Ball, Cylindrical,Roller, and Spherical-Roller TypeMetric Designs (AF-BMA Code 20BCO2JO)32.3 ASTM Adjuncts:Standard ball bearings (set of 5 ball bearings)43. Terminology3.1 Definitions of Terms Specific to
8、 This Standard:3.1.1 low-temperature torque, nthe torque in gcm re-quired to restrain the outer ring of a No. 6204 size open ballbearing lubricated with the test grease while the inner ring isrotated at 1 6 0.05 r/min at the test temperature.3.1.2 running torque, nthe 15-s average value of thetorque
9、 after rotation for a specified period of time (60 min).3.1.3 starting torque, nthe maximum torque measured atthe start of rotation.4. Summary of Test Method4.1 A No. 6204 open ball bearing is packed completely fullof the test grease and cleaned off flush with the sides. Thebearing remains stationar
10、y while ambient temperature is low-ered to the test temperature and held there for 2 h. At the endof this time, the inner ring of the ball bearing is rotated at 1 60.05 r/min while the restraining force on the outer ring ismeasured.4.2 Torque is determined by multiplying the restrainingforce by the
11、radius of the bearing housing. Both starting torqueand torque after 60 min of rotation (running torque) aredetermined.5. Significance and Use5.1 This test method was developed using greases havingvery low torque characteristics at 54C (65F). Specifica-tions for greases of this type commonly require
12、testing at thistemperature. Specifications for greases of other types canrequire testing at temperatures from 75 to 20C (100 to0F).5.2 This test method has proved helpful in the selection ofgreases for low-powered mechanisms, such as instrumentbearings used in aerospace applications. The suitability
13、 of thistest method for other applications requiring different greases,speeds, and temperatures should be determined on an indi-vidual basis.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.G0.05
14、 on Functional Tests - Temperature.Current edition approved May 1, 2011. Published May 2011. Originallyapproved in 1957. Last previous edition approved in 2007 as D147807. DOI:10.1520/D1478-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
15、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from AFBMA (Anti-Friction Bearing Manufacturers Association),1101 Connecticut Avenue, N.W., Suite 700, Washington, DC 200364303.4The ball bearing has been st
16、andardized by Subcommittee D02.G0. Availablefrom ASTM International Headquarters. Order Adjunct No. ADJD3336. Originaladjunct produced in 1984.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 Test Method D4693 may be better suited
17、 for applica-tions using larger bearings or greater loads. However, greaseshaving such characteristics that permit torque evaluations byeither this test method or Test Method D4693 will not give thesame values in the two test methods (even when converted tothe same torque units) because the apparatu
18、s and test bearingsare different.6. Apparatus6.1 Fig. 1 shows a suitable torque test apparatus assembly.It consists of the components described in 6.1.1-6.1.5.6.1.1 Low-Temperature BoxAny well-insulated box of atleast 0.03 m3(1 ft3) interior volume, in which the air tempera-ture can be controlled an
19、d maintained within 0.5C (1F) of thetest temperature. (WarningDirect impact on the test bearingby an air stream colder than the test temperature must beavoided to preclude erroneous results. Baffles should be usedwhere necessary to prevent such direct impact. The drivemechanism can be mounted extern
20、ally as shown in Fig. 2,orthe entire drive mechanism can be inserted directly into thebox. When the drive is mounted externally, the temperaturemeasured at a point on the surface of the test shaft between thetest bearing and wall of the box shall be not more than 0.5C(1F) above the test temperature.
21、)6.1.2 Drive Assembly, as shown in Fig. 2, including drivemotor, gear reductor, and test shaft. The test shaft shall receivethe test bearing against a shoulder having a diameter smallerthan the inner race shoulder of the bearing. Use a spacerwasher of the same diameter and at least 1.6 mm (116 in.)
22、thick,along with a test bearing lock nut, to clamp the inner ring of thetest bearing to the 1 r/min shaft.6.1.3 Housing (Cage)Bearing housing, load disk, loadring, clamp rod, and associated parts made in accordance withFig. 3. Adjust the mass of Part 2A (load disk) to be 454 6 3g(1 lb). Alternativel
23、y, if Part 2B (load ring) is used, adjust themass of Part 2B to be 454 6 3 g (1 lb).6.1.4 Torque-Measuring EquipmentA calibrated dyna-mometer scale5having a range of approximately 0 to 10 kg, 0to 100 N, or 0 to 25 lb, with a large face diameter (approxi-mately 200 mm (8 in.), or larger) and a suitab
24、le connectingcord of sufficient length (either braided metallic cable fittedwith a ring or loop on each end or a 15-kg (35-lb) test stringsaturated with silicone oil).NOTE 2Substitution of other suitable torque-measuring equipment,such as a strain-gage load cell, is permitted.6.1.5 Spindle and Greas
25、e Cup, as shown in Fig. 4 and Fig.5, respectively.7. Materials7.1 Test BearingNo. 6204 size open ball bearing (Stan-dard 20-1987,AFBMACode 20BCO2JO) containing eight 7.9mm (516 in.) balls, separated by a two-piece, pressed steel cage,and manufactured to ABEC-3 (Annular Bearing EngineeringCommittee)
26、tolerances with the standard radial clearance of0.021 to 0.028 mm (0.0008 to 0.0011 in.).4,67.2 Mineral Spirits, Reagent Grade.(WarningCombustible. Health Hazard.)7.3 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shal
27、l conform to the specifications of the commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.77.4 n-Heptane, reagent grade minimum purity. (WarningFlammable. Health Hazard.)8. Procedure8.1 Wash the selected test bearing thoroughly in mineralspirit
28、s and rinse it in a beaker of n-heptane. Dry the bearing forapproximately 20 min in a warm oven (not over 100C(212F). Permit the bearing to cool to room temperaturebefore proceeding.8.2 Lubricate the bearing with five drops of oil having aviscosity of 28 to 32 cSt at 100C (135 to 150 SUS at 210F).Th
29、e bearing shall then show no roughness or catching whenrotated between the fingers while applying light pressureaxially and then radially. Use the dynamometer to determine5The sole source of supply of the Dynamometer Scale, QDS-25 previouslyknown to the committee was R. Chatillon note the average an
30、dmaximum running torque peaks. The average shall not exceed20 gcm (2.0 mNm), and no peak shall exceed 25 gcm(2.5 mNm). If torque values fall below these limits, thebearing is suitable for the grease torque test. If torque valuesexceed these limits, the bearing should be recleaned andretested or disc
31、arded.8.3 Clean and dry a bearing that has been determined to beacceptable (8.2). Mount the bearing on a hand spindle (Fig. 4),fastening the inner race by means of the washer and screw. Fillthe grease cup (Fig. 5) at least three-fourths full of the testgrease, using a clean steel spatula. Minimize t
32、he inclusion ofair.8.4 Force the bearing down into the grease and rotate thespindle-bearing assembly slowly, first in one direction and thenthe other, to ensure that grease is worked into all parts of thebearing. When the bearing bottoms in the cup, slide thecylindrical cup ring off the plate and re
33、move the spindle-bearing assembly from the cup. (The assembly may be pushedor pulled through the cup.)FIG.2Drive(TopView)FIG. 3 Cage PartsD1478 1138.5 Remove the bearing from the spindle. Turn the bearingend-for-end, and refasten it on the spindle.8.6 Repack excess grease into the assembled grease c
34、up.Again, force the bearing down into the grease, while rotatingthe spindle-bearing assembly slowly, first in one direction andthen the other, until the bearing bottoms.8.7 Slide the cup ring off of the plate, and remove thespindle-bearing assembly from the cup ring. Scrape the excessgrease off flus
35、h with the sides of the bearing, filling any visiblevoids, and then remove the spindle. (WarningTake care notto rotate the bearing at any time after striking the grease flushand prior to the measurement of starting torque.)8.8 Insert the packed bearing into the test housing and fastenthe clamp cap o
36、ver the bearing.8.9 With the low-temperature box precooled to the testtemperature, open the box and slide the test bearing andhousing over the end of the test shaft. Fasten it with the washerand nut tightly enough to prevent slippage.8.10 Attach the cord under the head of the screw on theperiphery o
37、f the housing. Rotate the test shaft until the slack inthe cord hanging from the hook on the dynamometer scaleabove is almost taken up.The screw on the periphery must thenbe at least 90 degrees down from vertical. More than 90degrees is acceptable, provided that the cord does not slip offthe periphe
38、ry of the housing (Fig. 1).NOTE 3Measurements can also be made from horizontal or otherpositions if the cord attaching point is at or beyond the point of tangencyof the cord while torque is being measured. This will ensure a full 65-mm(2.56-in.) torque radius.8.11 Close the box, and recool it to the
39、 test temperature.Maintain this temperature within 60.5C (1F) for 2 h after thebox has recovered to the test temperature. (WarningDuringthis time the bearing must not be disturbed or the test will beinvalid.)8.11.1 It is desirable that excessive condensation of mois-ture from the air in the cold box
40、 be prevented, especially duringhumid weather. To this end and prior to the test, place shallowtrays containing a desiccant in the bottom of the low tempera-ture box.8.12 Check the torque cord to be sure it is free of ice and notstuck to the box.Asplit rubber stopper can be used to close thehole in
41、the box wall, through which the cord runs, to keep thecord and passage free of ice from moisture-laden air. Removethe stopper before the run.8.13 To determine starting torque, start the drive motor andobserve the dynamometer scale. Record the maximum readingand calculate the starting torque accordin
42、g to Section 9.8.14 Continue rotation of the test shaft for 60 min whilemaintaining the test temperature within 60.5C (1F). At theend of this time, observe the dynamometer reading for a periodof 15 s, and record the average value and calculate the runningtorque according to Section 9.8.15 When runni
43、ng repeat tests, the bearing shall be re-cleaned (see 8.1) and packed with a fresh charge of grease (see8.3 and 8.4) between tests. Do not force out tested grease witha fresh charge of grease.NOTE 4A pressure sprayer employing mineral spirits can be used toFIG. 4 SpindleD1478 114facilitate the remov
44、al of grease from the bearing.9. Calculation and Report9.1 Depending on the dynamometer scale calibration, cal-culate and report starting and running torques in gcm to threesignificant figures using the appropriate equation, as follows:9.1.1 For a scale calibrated in grams:torque 5 6.50 3 scale read
45、ing (1)9.1.2 For a scale calibrated in pounds:torque 5 2950 3 scale reading (2)9.1.3 For a scale calibrated in Newtons:torque 5 663 3 scale reading (3)9.2 To convert torque in gcm to torque in mNm, multiplyby 0.0981 and round to three significant figures.10. Precision and Bias8,910.1 PrecisionThe pr
46、ecision of this test method was notobtained in accordance with currently accepted guidelines (for8There is no research report on file because this test method was developedbefore research report guidelines were instituted, and data are no longer available.9The precision statement shown in this test
47、method was developed on nowobsolete equipment that is understood to be no longer commercially available.As noresearch report exists, it is not known how the precision statement was derived. Theprecision of the test on current commercially manufactured apparatus is unknown.FIG. 5 Grease CupD1478 115e
48、xample, Committee D02 Research Report RR:D02-1007,Manual on Determining Precision Data forASTM Methods onPetroleum Products and Lubricants).10.1.1 Alternative A:10.1.1.1 Low-temperature torque results derived from coop-erative testing using this procedure show appreciable scatter. Ingeneral, the dat
49、a were found to conform to Weibull probabilitydistributions, rather than the “normal” distributions aroundwhich ASTM statements of repeatability and reproducibilityare formulated. Weibull parameters such as Slope, L10, andL50 have been used to describe the test data.10.1.1.2 Precision may be judged from Fig. 6 and Fig. 7,Weibull plots for starting and running torques, respectively,and from the calculated Weibull parameters in Table 1.Precision may also be judged from the range for the center50 % of the reported test resul
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