ASTM_G_194_-_08_2013.pdf

Designation:G19408(Reapproved 2013)Standard Test Method forMeasuring Rolling Friction Characteristics of a SphericalShape on a Flat Horizontal Plane1This standard is issued under the fixed designation G194;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 covers the use of an angled launchramp to initiate rolling of a sphere or nearly spherical shape ona flat horizontal surface to determine the rolling frictioncharacteristics of a given spherical shape on a given surface.1.1.1 Steel balls on a surface plate were used in interlabo-ratory tests(see Appendix X1).Golf balls on a green,soccerand lacrosse balls on playing surfaces,bowling balls on an alane,basketballs on hardwood,and marbles on compositesurface were tested in the development of this test method,butthe test applies to any sphere rolling on any flat horizontalsurface.1.1.2 The rolling friction of spheres on horizontal surfaces isaffected by the spherical shapes stiffness,radius of curvature,surface texture,films on the surface,the nature of the counter-face surface;there are many factors to consider.This testmethod takes all of these factors into consideration.Thespherical shape of interest is rolled on the surface of interestusing a standard ramp to initiate rolling and standard tech-niques to measure and treat the rolled distance after leaving theramp.1.1.3 This test method produces a rolling resistance numberon a specific spherical shape on a specific surface.It is intendedfor comparing similar tribosystems.For example,the rollingresistances of marbles on a particular surface are not to becompared with the rolling resistance of soccer balls on grass,because their masses and diameters are very different as are thecounterface surfaces on which they roll.1.1.4 Different launch ramps for are appropriate for differenttypes of spherical shapes.If a sphere of interest cannot beaccommodated with using one of the launch ramps discussed inAppendix X1 and Appendix X2,a different launch ramp can bedeveloped and added with future revisions to this test method.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 ErosionG115 Guide for Measuring and Reporting Friction Coeffi-cientsG143 Test Method for Measurement of Web/Roller FrictionCharacteristics3.Terminology3.1 Definitions:3.1.1 rolling friction force,nin tribology,a force,oppositeto the direction of rolling,resisting rolling of a spherical shape,ball,roller,wheel,etc.forced against and rolling in a directionon another surface.G403.2 Definitions of Terms Specific to This Standard:3.2.1 coeffcientofrollingresistance(CORR)dimensionless measure of rolling retardation experienced by aspherical shape(sphere and the like)on a flat horizontal planeof interest;it is the ratio of the vertical distance between thespheres point of contact with the launch ramp and thehorizontal plane divided by the distance rolled on the horizon-tal plane after leaving the launch ramp.3.2.2 rolling resistance number(RR),ndimensionlessmeasure of the retardation produced on a spherical shaperolling on a flat horizontal surface:the higher the number,thehigher the retardation.This number is obtained by multiplyingthe CORR by 100.4.Summary of Test Method4.1 A vee-shaped launch ramp with known height,lengthand vee angle is placed on a flat and level(most flat and level1This 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 November 2013.Originallyapproved in 2008.Last previous edition approved in 2008 as G194 08.DOI:10.1520/G0194-13.2For 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 portion)of a surface of interest and a sphere(ball bearing,orange,golf ball,etc.)is rolled down the ramp onto the testsurface.The distance traveled after exiting the ramp is mea-sured.The ratio of the height of the spherical shapes outsidediameter above the test surface(plane)to the distance rolledafter leaving the ramp is the coefficient of rol