Designation:B439−12StandardSpecificationforIron-BasePowderMetallurgy(PM)Bearings(Oil-Impregnated)1ThisstandardisissuedunderthefixeddesignationB439;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope*1.1Thisspecificationcoverstherequirementsforporousiron-basemetallicsleeve,flange,thrust,andsphericalbearingsthatareproducedfrommetalpowdersutilizingpowdermetal-lurgy(PM)technologyandthenimpregnatedwithoiltosupplyoperatinglubrication.1.2Listedarethechemical,physical,andmechanicalspeci-ficationsforthosestandardizedferrousPMmaterialsthathavebeendevelopedspecificallyforthemanufactureofself-lubricatingbearings.1.3ThisstandardisacompaniontoSpecificationB438thatcoverstherequirementsforporousoil-imptegnatedbronze-basebearings.1.4Typicalapplicationsforself-lubricatingiron-basePMbearingsarediscussedinAppendixX1.1.5CommercialbearingdimensionaltolerancedataareshowninAppendixAppendixX2,whileengineeringinforma-tionregardinginstallationandoperatingparametersofPMbearingsisincludedinAppendixAppendixX3.Additionalusefulinformationonself-lubricatingbearingscanbefoundinMPIFStandard35(Bearings),ISO5755andthetechnicalliterature.21.6Units—Withtheexceptionofdensityvaluesforwhichtheuseoftheg/cm3unitisthelong-standingpracticeofthePMindustry,thevaluesstatedininch-poundunitsaretoberegardedasstandard.ThevaluesgiveninparenthesesaremathematicalconversionstoSIunitsthatareprovidedforinformationonlyandarenottoberegardedasstandard1.7Thefollowingsafetyhazardscaveatpertainsonlytothetestmethodsdescribedinthisspecification.Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregul...
