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1、MILLINGCUTTERS771MILLINGCUTTERSSelectionofMillingCutters.—Themostsuitabletypeofmillingcutterforaparticularmillingoperationdependsonsuchfactorsasthekindofcuttobemade,thematerialtobecut,thenumberofpartstobemachined,andthetypeofmillingmachineavailable.Solidcuttersof
2、smallsizewillusuallycostless,initially,thaninsertedbladetypes;forlong-runproduction,inserted-bladecutterswillprobablyhavealoweroverallcost.Dependingoneitherthematerialtobecutortheamountofproductioninvolved,theuseofcarbide-tippedcuttersinpreferencetohigh-speedstee
3、lorothercuttingtoolmaterialsmaybejustified.Rakeanglesdependonboththecuttermaterialandtheworkmaterial.Carbideandcastalloycuttingtoolmaterialsgenerallyhavesmallerrakeanglesthanhigh-speedsteeltoolmaterialsbecauseoftheirloweredgestrengthandgreaterabrasionresistance.S
4、oftworkmaterialspermithigherradialrakeanglesthanhardmaterials;thincutterspermitzeroorpracticallyzeroaxialrakeangles;andwidecuttersoperatesmootherwithhighaxialrakeangles.SeeRakeAnglesforMillingCuttersonpage801.Cuttingedgerelieforclearanceanglesareusuallyfrom3to6de
5、greesforhardortoughmaterials,4to7degreesforaveragematerials,and6to12degreesforeasilymachinedmaterials.SeeClearanceAnglesforMillingCutterTeethonpage800.Thenumberofteethinthemillingcutterisalsoafactorthatshouldbegivenconsider-ation,asexplainedinthenextparagraph.Num
6、berofTeethinMillingCutters.—Indeterminingthenumberofteethamillingcut-tershouldhaveforoptimumperformance,thereisnouniversalrule.Thereare,however,twofactorsthatshouldbeconsideredinmakingachoice:1)Thenumberofteethshouldneverbesogreatastoreducethechipspacebetweenthet
7、eethtoapointwhereafreeflowofchipsisprevented;and2)Thechipspaceshouldbesmoothandwithoutsharpcornersthatwouldcausecloggingofthechipsinthespace.Formillingductilematerialsthatproduceacontinuousandcurledchip,acutterwithlargechipspacesispreferable.Suchcoarsetoothcutter
8、spermitaneasierflowofthechipsthroughthechipspacethanwouldbeobtainedwithfinetoothcutters,andhelptoeliminatecutter“chatter.”Forcuttingoperationsinthinmaterials,f