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Ⅲ-21FrictionLubricationFrictionoflinearmotionrollingguideThestaticfriction(start-upfriction)oflinearmotionrollingguidesismuchlowerthanthatofconventionalplainguides.Also,thedifferencebetweenstaticfrictionanddynamicfrictionissmall,andfrictionalresistancevarieslittlewhenvelocitychanges.Theseareexcellentfeaturesoflinearmotionrollingguides,andaccountfortheirabilitytoreducepowerconsumption,suppressoperatingtemperaturerise,andincreasetravelingspeed.Sincefrictionalresistanceandvariationaresmall,high-speedresponsecharacteristicstomotioncommandsandhighaccuracypositioningcanbeachieved.FrictioncoefficientThefrictionalresistanceoflinearmotionrollingguidesvarieswiththeirmodel,appliedload,velocityandcharacteristicsoflubricant.Generally,lubricantorsealsaremajorfactorsindeterminingthefrictionalresistanceinlightloadorhigh-speedoperation,whiletheamountofloadisthemajorfactorinheavyloadorlowspeedoperation.Thefrictionalresistanceoflinearmotionrollingguidesdependsonvariousfactors,butgenerallythefollowingformulaisused.F=μP(13)where,F:Frictionalresistance,Nμ:DynamicfrictioncoefficientP:Appliedload,NForsealedguides,sealresistanceisaddedtotheabovevalue,butthisresistancevariesgreatlydependingontheinterferenceamountofseallipandlubricationconditions.Wherethelubricationandmountingconditionarecorrectandtheloadismoderate,thefrictioncoefficientsofLinearWayandLinearRollerWayinoperationarewithintherangeshowninTable10.Generally,frictioncoefficientislargeundersmallload.Table10FrictioncoefficientSeriesnameDynamicfrictioncoefficientμ(1)LinearWay0.0040～0.0060LinearRollerWay0.0020～0.0040Note(1)Thesefrictioncoefficientsdonotincludeseal.ObjectivesoflubricationTheobjectivesofapplyinglubricantforlinearmotionrollingguidesistokeepraceways,rollingelements,etc.inalinearmotionrollingguidefrommetalcontact,andtherebyreducefrictionandwearpreventingheatgenerationandseizure.Whenanadequateoilfilmisformedattherollingcontactareabetweentheracewaysandrollingelements,thecontactstressduetoloadcanbereduced.Tomanagetheformationofadequateoilfilmisimportantforensuringthereliabilityoflinearmotionrollingmechanism.SelectionoflubricantToobtainthefullperformanceoflinearmotionrollingguides,itisnecessarytoselectanappropriatelubricantandlubricationmethodbyconsideringthemodel,loadandvelocityofeachlinearmotionrollingguide.However,ascomparedwithplainguides,lubricationoflinearmotionrollingguidesismuchsimpler.Onlyasmallamountoflubricationoilisneededandreplenishmentintervalislonger,somaintenancecanbegreatlyreduced.Greaseandoilarethetwomostcommonlyusedlubricantsforlinearmotionrollingguides.GreaselubricationForlinearmotionrollingguides,lithium-soapbasegrease(ConsistencyNo.2ofJIS)iscommonlyused.Forrollingguidesoperatingunderheavyloadconditions,greasecontainingextremepressureadditivesisrecommended.Incleanandhigh-vacuumenvironments,wherelowdustgeneratingperformanceandlowvaporizationcharacteristicsarerequired,greasescontainingasynthetic-baseoilorasoapotherthanthelithium-soapbaseareused.Forapplicationsintheseenvironments,dueconsiderationisnecessarytoselectagreasethatissuitablefortheoperatingconditionsoflinearmotionrollingguideandachievessatisfactorylubricationperformanceatthesametime.Table11Pre-packedgreaselistSeriesnamePre-packedgreaseC-LubeLinearWayMLLinearWayLMULTEMPPSNo.2[KYODOYUSHICO.,LTD.]C-LubeLinearWayMLVC-LubeLinearWayMVAlvaniaEPGrease2[ShellLubricantsJapanK.K.]C-LubeLinearWayMELinearWayEC-LubeLinearWayMH(1)LinearWayH(1)LinearWayFC-LubeLinearWayMULLinearWayU(2)MULTEMPPSNo.2[KYODOYUSHICO.,LTD.]C-LubeLinearRollerWaySuperMXLinearRollerWaySuperXAlvaniaEPGrease2[ShellLubricantsJapanK.K.]LinearRollerWayXLinearWayModuleNotes(1)MULTEMPPSNo.2ispre-packedinsize8to12series.(2)lvaniaEPGrease2ispre-packedinsize40to86series.
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