附錄1英文原文英文原文CHAPTERIIICOSTSTUDYOFHIGH-SPEEDCUTTINGUNDERDRYANDWETCONDITIONSFORMACHININGPROCESSESOPTIMIZATION3.1IntroductionTheaimofthisstudyistooptimizethemachiningprocessesbyinvestigatingtherelationshipbetweenthehighspeedmachining(HSM)andthetoollifeforthecuttingconditionsundertesting.Furthermore,studyingtheeffectofcuttingfluidontheselectedwearcriterion,andrelationshipbetweendifferentwearcriteriaandmachiningcostforthecuttinginsertsunderHSM.Thisinvestigationshowedthatwearrateisproportionaltocuttingspeedsupportedwithsimilarobservations12,18,19.Studyingthecorrelationbetweenhighwearratesathighcuttingspeedandmachiningcosts,providesbetterunderstandingontheperformanceofthispolicyandthebenefitofitsadoption.Currently,littleornodatahavebeenpublishedrelatingthelife-cyclecosts,toolperformance,workpiecesurfaceroughnessandworkpiecedimensionalaccuracywhenusingsolidandindexablecutters10.However,studieshavefoundthattoolcostsinmetalcuttingmachinesareathirdofthecostofproducingparts.Thereforereducingproductcostisthefirstobjectiveofatoolmanagementsystem16.Thebenefitsofadoptingthisresearchguidelinewillhelpdeterminetheoptimalmachiningcostandtoolreplacementpolicybasedondifferentwearcriterionvalues.Additionallythisstudyprovidesinsightinprocesscontrolandhelpsthemanagersintheearlyprocessplanningstepstoassociatefactorssuchaspreventivemaintenance,levelsofinventory,andmachiningcost.3.2ExperimentalStudyThestudydevelopedaguidelineofchoosingtherightcuttingtool,cuttingspeed,andselectingtheappropriatewearcriteriaofthecuttingtoolinsertsfortheworkmaterialunderstudy.Inthisstudyvariablewearcriteriarangingfrom0.lmmto0.6mm(toollifelimit)weretakenintoconsideration.ThisexperimentwasconductedinaccordancewiththeInternationalStandardOrganizationISO3685199346.Thetestwasdoneona(Clausing1300)variablespindlespeedmachinewithamaximumpowerof7.5Hp(seeFigure3-1).Thetoolwearmeasurementswereperformedusinganopticalmicroscopewithamagnificationofupto300times,andaScanningElectronMicroscope(SEM).Therotationalspeedoftheworkpiecewasmeasuredbeforeeverycutbya(HT-5100)handhelddigitalTachometertoinsurethattheworkpiecewasaccuratelyrunningattheexactcuttingspeed.Ontheotherhand,theworkpiecematerialwasreplacedwhenthelength/diameterratioreaches10,basedonISO3685199346,toensureworkpiecestabilityandsafety.Twoprecutwerecarriedoutwith1.2mmdepth,tocleanupthethinlayerofrust,andtoensureworkpiecestraightness.Figure3-1Thetuningmachineusedduringthetest.3.2.1WorkpieceandCuttingInsertsInthisstudy,hotrolledASTM4140steelwasselectedastheworkpiecematerial.Theworkpiecepropertiesarelistedasfollows:Description:Hotrolledalloysteelbars,SAE4140H(UNSH4140)Dimensions:15cmDiameterx62.25cmlengthHeatTreatment:Vacuumdegassed/processed,Cal-Altreated,annealedandspecialstraightened,conformingtoASTMA322andA304Chemicalcompositions:ThecompositionoftheworkpiecematerialislistedinTable3.1accordingtotheASTMstandards.TheexperimentwascarriedoutinaccordancewiththeinternationalstandardorganizationISO3685-9346,theexperimentwasstoppedandtheworkpiecewaschangedwhenthelength/diameterratioreached10tomeettherequirementsofISO368546.Thehardnessofeachbarwascheckedacrossthediameter,andtheaveragehardnessmeasurementwas29HRC.ThetypesoftestedcuttingtoolinsertsarelistedonTable3.1accordingtotheISOdesignation.ThreetypesofcuttinginsertswereusedintheexperimentasillustratedinTable3-2；andthecoatingpropertiesarealsolistedinTable3-3.TheconfigurationoftheinvestigatedthreecuttinginsertswasthesameaslistedinTable3.4.ThegeneralcuttinginsertassembledgeometryisshowninFigure3-2.TheinsertsweremountedrigidlyonatoolholderaredepictedinFigure3-3withanISOdesignationofSVJBR2525M16.Table3-1ChemicalcompositionofASTM4140steelusedinthetestCuttinginsertsISODesignationSubstrateGradeCompanyUncoatedcementedCarbideVBMT160408.KC313KennametalTiAlNVBMT160408KC313KC5010KennametalTiN-TiCN-TiNVBMT160408KC313KC732KennametalTable3-2TypesofthetestedcuttinginsertsCarbonManganesePhosphorusSulfurSiliconNickelChromium0.40.910.0170.01Tin0.008Aluminum0.030Vanadium0.002Calcium0.0064Molly0.2Copper0.12Table3-3CoatingspropertiesCoatingThicknessNumberoflayersTiALN3.51TiN-TiCN-TiN3-3t-1t3(TiCNintermediate)3.2.2CoolantPropertiesItisacommonbeliefthatcoolantemulsionhelpsinreducingwearrateandcuttingtemperature.ThecoolantusedinthetestwaswaterbasedemulsionhascommercialnameNovick.Itismixedwithwaterataconcentrationof10%.ThecoolantcompositionincludesthelistedchemicalsinTable3.5.Previousresearchersonthebettercoolantstreamdirectionsmadedifferentsuggestions.Taylor17indicatedthattoreducetoolwearthecuttingfluidistobedirectedatthebackofthechip(directionA).PigottandColwell47foundthatbyusinghighstreamjetofcoolantaimedindirectionBitwasabletoreducetoolwear.SmartandTrent48investigatedthedirectionofcoolantinreducingthetoolwearandfoundthatthemosteffectivedirectionbetweenallothersuggestedoptionswasdirectionB.Therefore,coolantwasappliedindirectionBaslistedinFigure3.4fromanozzlewithdiameterof1.3cmandaflowrateof7.1liters/minute.However,thecurrentstudyshowedthatthisisnotnecessarilytrueinallcasesascoolantextendsthetoollife.Itwasfoundthatcoolantemulsionhelpedreducetoollifebyactivatingcertainwearmechanismathighspeedmachining(HSM).DetailedexplanationsofthistypeofcoolanteffectwillbediscussedinC