11CHAPTERVTOOLWEARMECHANISMSONTHEFLANKSURFACEOFCUTTINGINSERTSFORHIGHSPEEDWETMACHINING5.1IntroductionAlmosteverytypeofmachiningsuchasturning,milling,drilling,grinding.,usesacuttingfluidtoassistinthecosteffectiveproductionofpartsassetupstandardrequiredbytheproducer1.Usingcoolantwithsomecuttingtoolsmaterialcausesseverefailureduetothelackoftheirresistancetothermalshock(likeAL2O3ceramics),usedtoturnsteel.Othercuttingtoolsmaterialslikecubicboronnitride(CBN)canbeusedwithoutcoolant,duetothetypeoftheirfunction.TheaimofusingCBNistoraisethetemperatureoftheworkpicetohighsoitlocallysoftensandcanbeeasilymachined.Thereasonsbehindusingcuttingfluidscanbesummarizedasfollows.Extendingthecuttingtoollifeachievedbyreducingheatgeneratedandasaresultlesswearrateisachieved.Itwillalsoeliminatetheheatfromtheshearzoneandtheformedchips.Coolingtheworkpieceofhighqualitymaterialunderoperationplaysanimportantrolesincethermaldistortionofthesurfaceandsubsurfacedamageisaresultofexcessiveheatthatmustbeeliminatedorlargelyreducedtoproduceahighqualityproduct.Reducingcuttingforcesbyitslubricatingeffectatthecontactinterfaceregionandwashingandcleaningthecuttingregionduringmachiningfromsmallchips.Thetwomainreasonsforusingcuttingfluidsarecoolingandlubrication.CuttingFluidasaCoolant:Thefluidcharacteristicsandconditionofusedeterminethecoolantactionofthecuttingfluid,whichimprovestheheattransferat22theshearzonebetweenthecuttingedge,workpiece,andcuttingfluid.Thepropertiesofthecoolantinthiscasemustincludeahighheatcapacitytocarryawayheatandgoodthermalconductivitytoabsorbtheheatfromthecuttingregion.Thewater-basedcoolantemulsionwithitsexcellenthighheatcapacityisabletoreducetoolwear44.CuttingFluidasaLubricant:Thepurposeistoreducefrictionbetweenthecuttingedge,rakefaceandtheworkpiecematerialorreducingthecuttingforces(tangentialcomponent).Asthefrictiondropstheheatgeneratedisdropped.Asaresult,thecuttingtoolwearrateisreducedandthesurfacefinishisimproved.CuttingFluidPropertiesFreeofperceivableodorPreserveclaritythroughoutlifeKindandunirritatedtoskinandeyes.Corrosionprotectiontothemachinepartsandworkpiece.Costeffectiveintermsofftoollife,safety,dilutionratio,andfluidlife.15.1.1CuttingFluidTypesTherearetwomajorcategoriesofcuttingfluidsNeatCuttingOilsNeatcuttingoilsarepoorintheircoolantcharacteristicsbuthaveanexcellentlubricity.Theyareappliedbyfloodingtheworkareabyapumpandre-circulatedthroughafilter,tankandnozzles.Thistypeisnotdilutedbywater,andmaycontainlubricityandextreme-pressure33additivestoenhancetheircuttingperformanceproperties.Theusageofthistypehasbeendecliningfortheirpoorcoolingability,causingfirerisk,proventocausehealthandsafetyrisktotheoperator1.WaterBasedorWaterSolubleCuttingFluidsThisgroupissubdividedintothreecategories:1.Emulsionmineralsolublewhite-milkycolorasaresultofemulsionofoilinwater.Containfrom40%-80%mineraloilandanemulsifyingagentbesidecorrosioninhibitors,besidebiocidetoinhibitthebacteriagrowth.2.Microemulsionsemi-syntheticinventedin1980s,haslessoilconcentrationand/orhigheremulsifierratio10%-40%oil.Duetothehighlevelsofemulsifiertheoildropletsizeinthefluidaresmallerwhichmakethefluidmoretranslucentandeasytoseetheworkpieceduringoperation.Otherimportantbenefitisinitsabilitytoemulsifyanyleakageofoilfromthemachinepartsinthecuttingfluid,acorrosioninhibitors,andbacteriacontrol.3.Mineraloilfreesyntheticisamixofchemicals,water,bacteriacontrol,corrosioninhibitors,anddyes.Doesnotcontainanymineraloils,andprovidesgoodvisibility.23totheworkpiece.bareinmindthatthelackofmineraloilinthistypeofcuttingfluidneedstotakemoreattentiontomachinepartslubricationsinceitshouldnotleaveanoilyfilmonthemachineparts,andmightcausesealsdegradationduethelackofprotection.5.1.2CuttingFluidSelectionManyfactorsinfluencetheselectionofcuttingfluid；mainlyworkpiecematerial,typeofmachiningoperation,machinetoolparts,paints,andseals.Table5-1preparedatthemachinetoolindustryresearchassociation2providessuggestionsonthetypeoffluidtobe44used.5.1.3CoolantManagementToachieveahighlevelofcuttingfluidsperformanceandcosteffectiveness,acoolantrecyclingsystemshouldbeinstalledinthefactory.Thissystemwillreducetheamountofnewpurchasedcoolantconcentrateandcoolantdisposable,whichwillreducemanufacturingcost.Iteitherdonebythecompanyitselforberentedout,dependsonthebudgetandmanagementpolicyofthecompany1.Table5-1Guidetotheselectionofcuttingfluidsforgeneralworkshopapplications.MachiningoperationWorkpiecematerialFreemachiningandlow-carbonsteelsMedium-CarbonsteelsHighCarbonandalloysteelsStainlessandheattreatedresistantalloysGrindingCleartypesolubleoil,semisyntheticorchemicalgrindingfluidTurningGeeralprpose,solubleoil,semisyntheticorsyntheticfluidExtreme-pressuresolubleoil,semi-syntheticorsyntheticfluidMillingGeneralpurpose,solubleoil,semisyntheticorsyntheticfluidExtreme-pressuresolubleoil,semi-syntheticorsyntheticfl