附錄2英語原文TheComputerandManufacturingComputerAidedDesignThecomputerisbringingmanufacturingintotheInformationAge.Thisnewtool,alongfamiliaroneinbusinessandmanagementoperations,ismovingintothefactory,anditsadventischangingmanufacturingascertainlyasthesteamenginechangedit100yearsago.Thebasicmetalworkingprocessesarenotlikelytochangefundamentally,buttheirorganizationandcontroldefinitelywill.INonerespect,manufacturingcouldbesaidtobecomingfullcircle.Thefirstmanufacturingcouldwasacottageindustry:thedesignerwasalsothemanufacturer,conceivingandfabricatingproductsoneatatime.Eventually,theconceptoftheinterchangeabilityofpartswasdeveloped,productionwasseparatedintospecializedfunctions,andidenticalpartswereproducedthousandsatatime.Today,althoughthedesignerandmanufacturermaynotbecomeoneagain,thefunctionsarebeingdrawncloseinthemovementtowardanintegratedmanufacturingsystem,Itisperhapsironicthat,atatimewhenthemarketdemandahighdegreedofproductdiversification,thenecessityforincreasingproductivityandreducingcostsisdrivingmanufacturingtowardintegrationintoacoherentsystem,acontinuousprocessinwhichpartsdonotspendasmuchas95%ofproductiontimebeingmovedaroundorwaitingtobeworkedon.Thecomputeristhekeytoeachofthesetwinrequirements.Itistheonlytoolthatcanprovidethequickreflexes,theflexibilityandspeed,tomeetadiversifiedmarket.Anditistheonlytoolthatenablesthedetailedanalysisandtheaccessibilityofaccuratedatanecessaryfortheintegrationofthemanufacturingsystem.Itmaywellbethat,inthefuture,thecomputermaybeessentialtoacompanyssurvival.Manyoftodaysbusinesseswillfadeawaytobereplacedbymore-productivecombinations.Suchmore-productivecombinationsaresuper-quality,super-productivityplants.Thegoalistodesignandoperateaplantthatwouldproduce100%satisfactorypartswithgoodproductivity.Asophisticated,competitiveworldisrequiringthatmanufacturingbegintosettleformore,tobecomeitselfsophisticated,Tomeetcompetition,forexample,acompanywillhavetomeetthesomewhatconflictingdemandsforgreaterproductdiversification,higherquality,improvedproductivity,andlowprices.Thecompanythatseekstomeetthesedemandswillneedasophisticatedtool,onethatwillallowittorespondquicklytocustomerneedswhilegettingthemostoutofitsmanufacturingresources.Thecomputeristhattool.Becominga“super-quality,super-productivity”plantrequirestheintegrationofanextremelycomplexsystem.Thiscanbeaccomplishedonlywhenallelementsofmanufacturingdesign,fabricationandassembly,qualityassurance,management,materialshandlingarecomputerintegrated.Inproductdesign,forexample,interactivecomputer-aided-design(CAD)systemsallowthedrawingandanalysistaskstobeperformedinafractionofthetimepreviouslyrequiredandwithgreateraccuracy.Andprogramsforprototypetestingandevaluationfurtherspeedthedesignprocess.Inmanufacturingplanning,computer-aidedprocessplanningpermitstheselection,fromthousandsofpossiblesequencesschedules,oftheoptimumprocess.Ontheshopfloor,distributedintelligenceintheformofmicroprocessorscontrolsmachines,runsautomatedloadingandunloadingequipment,andcollectsdataoncurrentshopconditions.Butsuchisolatedrevolutionsarenotenough.Whatisneededisatotallyautomatedsystem,linkedbycommonsoftwarefromfrontdoortoback.Thebenefitsrangethroughoutthesystem.Essentially,computerintegrationprovideswidelyandinstantaneouslyavailable,accurateinformation,improvingcommunicationbetweendepartments,permittingtightercontrol,andgenerallyenhancingtheoverallqualityandefficiencyoftheentiresystem.Improvedcommunicationcanmean,forexample,designsthataremoreproducible.TheNCprogrammerandthetooldesignerhaveachancetoinfluencetheproductdesigner,andviceversa.Engineeringchanges,thus,canbereduced,andthosethatarerequiredcanbehandledmoreefficiently.Notonlydoesthecomputerpermitthemtobespecifiedmorequickly,butitalsoalertssubsequentusersofthedatatothefactthatachangehasbeenmade.Theinstantaneousupdatingofproduction-controldatapermitsbetterplanningandmore0effectivescheduling.Expensiveequipment,therefore,isusedmoreproductively,andpartsmovemoreefficientlythroughproduction,reducingwork-in-processcosts.Productquality,too,canbeimproved.Notonlyaremore-accuratedesignsproduced,forexample,buttheuseofdesigndatabythequality-assurancedepartmenthelpseliminateerrorsduetomisunderstandings.Peopleareenabledtodotheirjobsbetter.Byeliminatingtediouscalculationsandpaperworknottomentiontimewastedsearchingforinformationthecomputernotonlyallowsworkerstobemoreproductivebutalsofreesthemtodowhatonlyhumanbeingscando:thinkcreatively.Computerintegrationmayalsolurenewpeopleintomanufacturing.Peopleareattractedbecausetheywanttoworkinamodern,technologicallysophisticatedenvironment.Inmanufacturingengineering,CAD/CAMdecreasestool-design.NC-programming,andplanningtimeswhilespeedingtheresponserate,whichwilleventuallypermitin-housestafftoperformworkthatiscurrentlybeingcontractedout.AccordingtotheTool&ManufacturingEngineersHandbook,processplanningisthesystematicdeterminationofthemethodsbywhichaproductistobemanufacturedeconomicallyandcompetitively.Itessentiallyinvolvesselection,calculation,anddocumentation.Processes,machines,tools,andsequencesmustbeselected.Suchfactorsasfeeds,speeds,tolerances,dimensions,andcostsmustbecalculated.Finally,documentsintheformofsetupinstructions,workinstructions,illustratedprocesssheets,androutingsmustbeprepared.Processplanningisanintermediatestagebetweendesigningandmanufacturingtheproduct.Buthowwelldoesitbridgedesignandmanufacturing?Mostmanufacturingengineerswouldagreethat,iftendifferentplannerswereaskedtodevelopaprocessplanforthesamepart,theywouldprobablycomeupwithtendifferentplans.Obviously,alltheseplanscannotreflectthemostefficientmanufacturingmethods,and,infact,thereisnoguaranteethatanyoneofthemwillconstitutetheoptimummethodsformanufacturingthepart.Whatmaybeevenmoredisturbingisthataprocessplandevelopedforapartduringacurrentmanufacturingprogrammaybequitedifferentmanufacturingprogramanditmayneverbeusedagainforthesameorsimilarpartduringaprevioussimilarpart.Thatrepresentsalotofwastedeffortandproducesagreatmanyinconsistenciesinrouting,tooling,laborrequirements,costing,andpossiblyevenpurchaserequirements.Ofcourse,processplansshouldnotnecessarilyremainstatic.Aslotsizeschangeandnewtechnology,equipment,andprocessesbecomeavailable,themosteffectivewaytomanufactureaparticularpartalsochanges,andthosechangesshouldbereflectedincurrentprocessplansreleasedtotheshop.Aplannermustmanageandretrieveagreatdealofdataandmanydocuments,includingestablishedstandards,machineabilitydata,machinespecifications,toolinginventories,stockavailability,andexistingprocessplans.Thisisprimarilyaninformation-handlingjob,andthecomputerisanidealcompanion.Thereisanotheradvantagetousingcomputerstohelpwithprocessplanning.Becausethetaskinvolvesmanyinterrelatedactivities,determiningtheoptimumplanrequiresmanyiterations.Sincecomputerscanreadilyperformvastnumbersofcompariso