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1、Word格式外文原文Optionsformicro-holemakingAsinthemacroscale-machiningworld,holemakingisoneofthemost—ifnotthemost—frequentlyperformedoperationsformicromachining.Manyoptionsexistforhowthoseholesarecreated.Eachhasitsadvantagesandlimitations,dependingontherequiredholediameteranddepth,workpiecematerialan
2、dequipmentrequirements.Thisarticlecoversholemakingwiththrough-coolantdrillsandthosewithoutcoolantholes,plungemilling,microdrillingusingsinkerEDMsandlaserdrilling.HelpfulHolesGettingcoolanttothedrilltipwhilethetooliscuttinghelpsreducetheamountofheatatthetool/workpieceinterfaceandevacuatechipsre
3、gardlessofholediameter.Butthrough-coolantcapabilityisespeciallyhelpfulwhendeep-holemicrodrillingbecausethetoolsaredelicateandpronetofailurewhenexperiencingrecuttingofchips,chippackingandtoomuchexposuretocarbide’sworstenemy—heat.Whenapplyingfloodcoolant,thedrillitselfblocksaccesstothecuttingact
4、ion.“Somewhereabout3to5diametersdeep,thecoolanthastroublegettingdowntothetip,”saidJeffDavis,vicepresidentofengineeringforHarveyToolCo.,Rowley,Mass.“Itbecomeswisetouseacoolant-feddrillatthatpoint.”Inaddition,floodcoolantcancausemoreharmthangoodwhenmicroholemaking.“Thepressurefromthefloodcoolant
5、cansometimessnapfragiledrillsastheyenterthepart,”Davissaid.Thetoolmakeroffersalineofthrough-coolantdrillswithdiametersfrom0.039"to0.125"thatareabletoproduceholesupto12diametersdeep,aswellasmicrodrillswithoutcoolantholesfrom0.002"to0.020".Havingthrough-coolantcapacityisn’tenough,though.Coolantn
6、eedstoflowataratethatenablesittoclearthechipsoutofthehole.Davisrecommends,ataminimum,600to800psiofcoolantpressure.“Itworksmuchbetterifyouhavehigherpressurethanthat,”headded.Topreventthosetinycoolantholesfrombecomingcloggedwithdebris,Davisalsorecommendsa5μmorfinercoolantfilter.Anotherrecommenda
7、tionistomachineapilot,orguide,holetoprevent完美整理Word格式thetoolfromwanderingontopoftheworkpieceandaidinproducingastraighthole.Whenapplyingapilotdrill,it’simportanttoselectonewithanincludedangleonitspointthat’sequaltoorlargerthantheincluded
