ASTM_G_182_-_13.pdf

Designation:G18213Standard Test Method forDetermination of the Breakaway Friction Characteristics ofRolling Element Bearings1This standard is issued under the fixed designation G182;the number immediately following the 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.Scope1.1 This test method is an extension of Test Method G164and uses an inclined plane and a paperclip rider to detect thepresence or absence of lubricants on the surfaces of flexiblewebs.A study to identify free spinning or low rolling frictionbearings indicated that the paperclip friction test could be usedfor rolling friction by simply replacing the paperclip with arolling element bearing on an axle.The angle of the inclinedplane at initiation of rolling is the breakaway angle.This testmethod can be used to measure the angle at breakaway of smalldiameter(up to 100 mm outside diameter)rolling elementbearings.The bearings that have been tested in the develop-ment of this method are conventional ball bearings withdifferent separators,seals,and different conditions of lubrica-tion(none,oil,greases,and so forth),but there is no technicalreason why this test method would not work with bearings ofother design,including plain bearings.Rolling element bear-ings like any sliding system can have friction characteristics atbreakaway that are different than rolling continuously.As is thecase with most inclined plane friction tests,the test onlyproduces the friction characteristic at the onset of measurablerolling,using the angle()when measurable rolling com-mences.The objective of this test is an assessment of break-away rolling friction characteristics to assist machine designersin the selection of rolling element bearings for instrumentpivots and the like where breakaway friction is a concern.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2G40 Terminology Relating to Wear and ErosionG117 Guide for Calculating and Reporting Measures ofPrecision Using Data from Interlaboratory Wear or Ero-sion TestsG143 Test Method for Measurement of Web/Roller FrictionCharacteristicsG164 Test Method for Determination of Surface Lubricationon Flexible Webs3.Terminology3.1 Definitions Relating to Wear and Erosion(taken fromTerminology G40):3.1.1 coeffcient of friction,in tribology,the dimension-less ratio of the friction force(F)between two bodies to thenormal force(N)pressing these bodies together.3.1.2 friction forcethe resisting force tangential to theinterface between two bodies when,under the action ofexternal force,one body moves or tends to move relative to theother.3.1.3 kinetic coeffcient of frictionthe coefficient of fric-tion under conditions of macroscopic relative motion betweentwo bodies.3.1.4 lubricantany substance interposed between two sur-faces for the purpose of reducing the friction and wear betweenthem.3.2 Definitions Not Covered by Terminology G40:3.2.1 breakaway coeffcient of rolling frictionthe force inthe direction of rolling(F)required to produce rolling of ashape that is capable of rolling on a surface,divided by thenormal force(N)on the rolling shape:rolling5FN(1)3.2.2 inclined planea surface that can be raised at an angleto produce motion of an object on the plane.1This test method is under the jurisdiction of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.50 on Friction.Current edition approved Nov.15,2013.Published December 2013.Originallyapproved in 2006.Last previous edition approved in 2006 as G182 06.DOI:10.1520/G0182-13.2For referenced ASTM standards,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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.3 plain bearingsa cylindrical shape used to support arotating shaft.3.2.4 rolling element bearingballs or rollers in racewaysthat support a shaft and allow rotation of the shaft or bearingouter race(OD).4.Summary of Test Method4.1 This test method can be used to measure the breakawayrolling friction characteristics of rolling element bearings.4.2 Small rolling element bearings(less than 100 mmoutside diameter)are affixed to a balanced rider and placed onan incline.The rider is designed so that it becomes the axleabout which the bearing rot