第1页共7页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第1页共7页Machining:AnIntroductionIntermsofannualdollarsspent,machiningisthemostimportantofthemanufacturingprocesses.Machiningcanbedefinedastheprocessofremovingmaterialfromaworkpieceintheformofchips.Thetermmetalcuttingisusedwhenthematerialismetallic.Mostmachininghasverylowset-upcostcomparedtoforming,molding,andcastingprocesses.However,machiningismuchmoreexpensiveforhighvolumes.Machiningisnecessarywheretighttolerancesondimensionsandfinishesarerequired.TheMachiningsectionisdividedintothefollowingcategories:Drilling:IntroductionDrillingiseasilythemostcommonmachiningprocess.Oneestimateisthat75%ofallmetal-cuttingmaterialremovedcomesfromdrillingoperations.Drillinginvolvesthecreationofholesthatarerightcircularcylinders.Thisisaccomplishedmosttypicallybyusingatwistdrill,somethingmostreaderswillhaveseenbefore.Thefigurebelowillustratesacrosssectionofaholebeingcutbyacommontwistdrill:Thechipsmustexitthroughtheflutestotheoutsideofthetool.Ascanbeseeninthefigure,thecuttingfrontisembeddedwithintheworkpiece,makingcoolingdifficult.Thecuttingareacanbeflooded,coolantspraymistcanbeapplied,orcoolantcanbedeliveredthroughthedrillbitshaft.Foranoverviewofthechip-formationprocess,seetheChipFormationSection.DrillingCharacteristicsThecharacteristicsofdrillingthatsetitapartfromotherpoweredmetalcuttingoperationsare:Thechipsmustexitoutoftheholecreatedbythecutting.Chipexitcancauseproblemswhenchipsarelargeand/orcontinuous.Fordeepholesinlargeworkpieces,coolantmayneedtobedeliveredthrough第2页共7页第1页共7页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第2页共7页thedrillshafttothecuttingfront.Ofthepoweredmetalcuttingprocesses,drillingonadrillpressisthemostlikelytobeperformedbysomeonewhoisnotamachinist.DrillPressWorkAreaAviewofthemetal-cuttingareaofadrillpressisshownbelow.Theworkpieceisheldinplacebyaclampsincecuttingforcescanbequitelarge.Itisdangeroustoholdaworkpiecebyhandduringdrillingsincecuttingforcescanunpredictablygetquitelargeandwrenchthepartaway.Woodisoftenusedunderneaththepartsothatthedrillbitcanovershootwithoutdamagingthetable.Thetablealsohasholesfordrillovershootaswellasweightreduction.Athree-jawchuckisusedsincethreepointsdetermineacircleintwodimensions.Four-jawchucksarerarelyseensinceoffsetofthebitisnotnecessary.Thenextsectioncontainsillustrationsofdrillbitchucks.Togetanideaofthedifferingconfigurationsofthreeandfour-jawchucks,pleaseseetheequivalentlathechucks.Turning:EngineLatheTurningisanotherofthebasicmachiningprocesses.Informationinthissectionisorganizedaccordingtothesubcategorylinksinthemenubartotheleft.ÂTurningproducessolidsofrevolutionwhichcanbetightlytolerancedbecauseofthespecializednatureoftheoperation.Turningisperformedonamachinecalledalatheinwhichthetoolisstationaryandthepartisrotated.Thefigurebelowillustratesanenginelathe.Lathesaredesignedsolelyforturningoperations,sothatprecisecontrolofthecuttingresultsintighttolerances.Theworkpieceismountedonthechuck,whichrotatesrelativetothestationarytool.第3页共7页第2页共7页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第3页共7页TurningTurningreferstocuttingasshownbelow.Theterm"facing"isusedtodescriberemovalofmaterialfromtheflatendofacylindricalpart,asshownbelow.Facingisoftenusedtoimprovethefinishofsurfacesthathavebeenparted.第4页共7页第3页共7...
