ASTM_D_4170_-_10.pdf

Designation:D417010Standard Test Method forFretting Wear Protection by Lubricating Greases1This standard is issued under the fixed designation D4170;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.Scope*1.1 This test method evaluates the fretting wear protectionprovided by lubricating greases.1.2 The values stated in SI units are to be regarded as thestandard.Other units are for information only.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.For specificwarning statements,see 7.2 and 9.2.2.Referenced Documents2.1 ASTM Standards:2Test Methods for Rating Motor,Diesel,and Aviation Fuels;Motor Fuels(Section I),Reference Materials and Blend-ing Accessories(Annex 2),Reference Fuels(A2.7.3.3),and Table 32(Specification for n-Heptane Motor Fuel)2.2 Military Standard:3MIL-S-22473D Sealing,LockingandRetainingCompounds,Single-Component3.Terminology3.1 Definitions:3.1.1 fretting wear,na form of attritive wear caused byvibratory or oscillatory motion of limited amplitude character-ized by the removal of finely-divided particles from therubbing surfaces.43.1.1.1 DiscussionAir can cause immediate local oxida-tion of the wear particles produced by fretting wear.Inaddition,environmental moisture or humidity can hydrate theoxidation product.In the case of ferrous metals,the oxidizedwear debris is abrasive iron oxide(Fe2O3)having the appear-ance of rust,which gives rise to the nearly synonymous terms,fretting corrosion and friction oxidation.A related,but some-what different phenomenon often accompanies fretting wear.False brinelling is localized fretting wear that occurs when therolling elements of a bearing vibrate or oscillate with smallamplitude while pressed against the bearing race.The mecha-nism proceeds in stages:(1)asperities weld,are torn apart,andform wear debris that is subsequently oxidized;(2)due to thesmall-amplitude motion,the oxidized detritus cannot readilyescape,and being abrasive,the oxidized wear debris acceler-ates the wear.As a result,wear depressions are formed in thebearing race.These depressions appear similar to the Brinelldepressions obtained with static overloading.Although falsebrinelling can occur in this test,it is not characterized as such,and instead,it is included in the determination of fretting wear.4.Summary of Test Method4.1 The tester is operated with two ball thrust bearings,lubricated with the test grease,oscillated through an arc of 0.21rad(12),at a frequency of 30.0 Hz(1800 cpm),under a loadof 2450 N(550 lbf),for 22 h at room temperature(Note 1).Fretting wear is determined by measuring the mass loss of thebearing races.NOTE1Arc,frequency,and load are factory-set operating conditionsand should not be altered.The load spring constant may change over anextended time period.Spring calibration should be checked periodicallyand,if necessary,a suitable shim should be fabricated to obtain therequired load(63%)at the assembled length of the spring.5.Significance and Use5.1 This test method is used to evaluate the property oflubricating greases to protect oscillating bearings from frettingwear.This method,used for specification purposes,differenti-ates among greases allowing low,medium,and high amountsof fretting wear under the prescribed test conditions.The testhas been used to predict the fretting performance of greases inwheel bearings of passenger cars shipped long distances.5Testresults do not necessarily correlate with results from othertypes of service.It is the responsibility of the user to determinewhether test results correlate with other types of service.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.G0.04 on Functional Tests-Tribology.Current edition approved May 1,2010.Published June 2010.Originallyapproved in 1982.Last previous edition approved in 2002 as D417097(2002)1.DOI:10.1520/D4170-10.2See 1998 Annual Book of ASTM Standards,Vol 05.04.3Available from Standardization Documents Order Desk,DODSSP,Bldg.4,Section D,700 Robbins Ave.,Philadelphia,PA 19111-5098.4NLGI Lubricating Grease Guide,3rd edition.5Verdura,T.M.,“Development of a Standard Test to Evaluate FrettingProtection Quality of Lubricating Grease,”NLGI Spokesman,Vol XLVII,No.5,August 1983,pp.15767.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Apparatus6.1 Falex Fretting Wear Tester,Model F-1581,6,7as