1NewToolsMaximizeNewMachineDesignsTheprimarytoolingconcernswhenmachiningaluminumare:minimizingthetendencyofaluminumtosticktothetoolcuttingedges；ensuringthereisgoodchipevacuationformthecuttingedge；andensuringthecorestrengthofthetoolsissufficienttowithstandthecuttingforceswithoutbreaking.TechnologicaldevelopmentssuchastheMakinoMAG-Seriesmachineshavemadetoolingvendorsrethinktheanystate-of-the-artmachinetechnology.Itisvitaltoapplytherighttoolingandprogrammingconcepts.Materialscoatingsandgeometryarethethreeelementsintooldesignthatinterrelatetominimizetheseconcerns.Ifthesethreeelementsdonotworktogether,successfulhigh-speedmillingisnotpossible.Itisimperativetounderstandallthreeoftheseelementsinordertobesuccessfulinthehigh-speedmachiningofaluminum.MinimizeBuilt-UpEdgeWhenmachiningaluminum,oneofthemajorfailuremodesofcuttingtoolsthematerialbeingmachinedadherestothetoolcuttingedge.Thisconditionrapidlydegradesthecuttingabilityofthetool.Thebuilt-upedgethatisgeneratedbytheadheringaluminumdullsthetoolsoitcannolongercutthroughthematerial.Toolmaterialselectionandtoolcoatingselectionarethetwoprimarytechniquesusedbytooldesignerstoreduceoccurrenceofthebuilt-upedge.Thesub-microngraincarbidematerialrequiresahighcobaltconcentrationtoachievethefinegrainstructureandthematerialsstrengthproperties.Cobaltreactswithaluminumatelevatedtemperatures,whichcausesthealuminumtochemicallybondtotheexposedcobaltofthetoolmaterial.Oncethealuminumstartstoadheretothetool,itquicklyformsabuilt-upedgeonthetoolrenderingitineffective.Thesecretistofindtherightbalanceofcobalttoprovideadequatematerialstrength,whileminimizingtheexposedcobaltinthetoolsforaluminumadherenceduringthecuttingprocess.Thisbalanceisachievedusingcoarse-grainedcarbidethatprovidesatoolofsufficienthardnesssoastonotdullquicklywhenmachiningaluminumwhileminimizingadherence.ToolCoatingsThesecondtooldesignelementthatmustbeconsideredwhentryingtominimizethebuilt-upedgeisthetoolcoating.ToolcoatingchoicesincludeTiN,TiAIN,AITiN,chromenitrides,zirconiumnitrides,diamond,anddiamond-likecoatings(DLC).With2somanychoices,aerospacemillingshopsneedtoknowwhichoneworksbestinanaluminumhigh-speedmachiningapplication.ThePhysicalVaporDeposition(PVD)coatingapplicationprocessonTiN,TiCN,TiAIN,andAITiNtoolsmakesthemunsuitableforanaluminumapplication.ThePVDcoatingprocesscreatestwomodesforaluminumtobondtothetoolsthesurfaceroughnessandthechemicalreactivitybetweenthealuminumandthetoolcoating.ThePVDprocessresultsinsurfacethatisrougherthatthesubstratematerialtowhichitisapplied.Thesurface”peaksandvalleys”createdbythisprocesscausesaluminumtorapidlycollectinthevalleysonthetool.Inaddition,thePVDcoatingischemicallyreactivetothealuminumduetoitsmetalliccrystalandioniccrystalfeatures.ATiAINcoatingactuallycontainsaluminum,whicheasilybondswithacuttingsurfaceofthesamematerial.Thesurfaceroughnessandchemicalreactivityattributeswillcausethetoolandworkpiecetosticktogether,thuscreatingthebuilt-upedge.IntestingperformedbyOSGTapandDie,itwasdiscoveredthatwhenmachiningaluminumatveryhighspeeds,theperformanceofanuncoatedcoarse-grainedcarbidetoolwassuperiortothatofonecoatedwithTiN,Ticn,TiAIN,orALTiN.Thistestingdoesnotmeanthatalltoolcoatingswillreducethetoolperformance.ThediamondandDLCcoatingsresultinaverysmoothchemicallyinertsurface.Thesecoatingshavebeenfoundtosignificantlyimprovetoollifewhencuttingaluminummaterials.Thediamondcoatingswerefoundtobethebestperformingcoatings,butthereisaconsiderablecostrelatedtothistypeofcoating.TheDLCcoatingsprovidethebestcostforperformancevalue,addingabout20%-25%tothetotaltoolcost.But,thiscoatingextendsthetoollifesignificantlyascomparedtoanuncoatedcoarse-grainedcarbidetool.GeometryTheruleofthumbforhigh-speedaluminummachiningtoolingdesignsistomaximizespaceforchipevacuation.Thisisbecausealuminumisaverysoftmaterial,andthefederateisusuallyincreasedwhichcreatesmoreandbiggerchips.TheMakinoMAG-Seriesaerospacemillingmachines,suchastheMAG4,requireanadditionalconsiderationfortoolgeometry-toolstrength.TheMAG-Seriesmachineswiththeirpowerful80-hpspindleswillsnapthetoolsiftheyarenotdesignedwithsufficientcorestrength.Ingeneral,sharpcuttingedgesshouldalwaysbeusedtoavoidaluminum3elongation.Asharpcuttingedgewillcreatehighshearingandalsohighsurfaceclearance,creatingabettersurfacefinishandfinishandminimizingchatterorsurfacevibration.Theissueisthatitispossibletoachieveasharpercuttingedgewiththefine-grainedcarbidematerialthanthecoarsegrainedmaterial.Butduetoaluminumadherencetothefine-grainedmaterial,itisnotpossibletomaintainthatedgeforverylong.CoarseCompromiseThecoarsegrainedmaterialappearstobethebestcompromise.Itisastrongmaterialthatcanhaveareasonablecuttingedge.Testresultsshowitisabletoachieveaverylongtoollifewithgoodsurfacefinish.Themaintenanceofthecuttingedgeisimprovedusinganoilmistcoolantthroughthetool.Mistinggraduallycoolsdownthetools,eliminatingthermalshockproblems.Thehelixangleisanadditionaltoolgeometryconsideration.Traditionallywhenmachiningaluminumafoolwithahighhelixanglehasbeenused.Ahighhelixangleliftsthechipawayfromthepartmorequickly,butincreasesthefrictionandheatgeneratedasresultofthecuttingaction.Ahighhelixangleistypicallyusedonatoolwithahighernumberofflutestoquicklyevacuatethechipfromthepart.Whenmachiningaluminumatveryhighspeedstheheatcreatedbytheincreasedfrictionmaycausethechipstoweldtothetool.Inaddition,acuttingsurfacewithahighhelixanglewillchipmorerapidlythatatoolwithalowhelixangle.Atooldesignthatutilizesonlytwoflutesenablesbothalowhelixangleandsufficientchipevacuationarea.ThisistheapproachthathasproventobethemostsuccessfulinextensivetestingperformedbyOSGwhendevelopingthenewtoolingline,themaxal.4新工具使新機(jī)器設(shè)計(jì)最優(yōu)當(dāng)加工鋁時(shí)，我們主要關(guān)心的是：鋁粘住加工切削邊緣的傾向；保證有好的碎片排屑形成切削邊緣；和保證工具有足夠的中心強(qiáng)度來承受切削力而不被破壞。技術(shù)發(fā)展，比如：MakinoMAG系列，已經(jīng)使工具商重新考慮任何工藝水平的機(jī)器技術(shù)。用正確的加工和編程思路是很重要的。材料，涂