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0JOURNALOFMANUFACTURINGSYSTEMSWVOL2UNO1D2002TRENDSANDPERSPECTIVESCOMPUTERAIDEDFIXTUREDESIGNUSINGINFORMATIONINTENSIVEFUNCTIONMODELSINTHEDEVELOPMENTOFAUTOMATEDFIXTUREDESIGNSYSTEMSJCECIL,ASSISTANTPROFESSOR,VIRTUALENTERPRISEENGINEERINGLABVEEL,INDUSTRIALENGINEERINGDEPT,NEWMEXICOSTATEUNIVERSITY,LASCRUCES,NEWMEXICO,USAABSTRACTINTHISPAPER,THEDEVELOPMENTOFANINFORMATIONINTENSIVEFUNCTIONMODELIIFMOFFIXTUREDESIGNACTIVITIESISDISCUSSEDTHISFUNCTIONMODELWASDEVELOPEDUSINGTHEIDEF0INTEGRATEDDEFINITIONMETHODOLOGYANDWASBUILTPRIMARILYAFTERINTERACTINGWITHEXPERTFIXTUREDESIGNERSINADDITION,KNOWLEDGEFROMFIXTUREDESIGN,TOOLDESIGN,ANDMETALCUTTINGHANDBOOKSANDFROMJOURNALPAPERSWASUSEDTOLENDAHOLISTICFLAVORTOTHEDEVELOPEDIDEF0MODELANIDEF0MODELINGSOFTWARETOOL,AI0WIN,WASUSEDTOBUILDTHISMODELATVARIOUSLEVELSOFDECOMPOSITIONTHISPAPERALSODISCUSSESTHEIMPORTANCEOFILFMSINTHECURRENTANDFUTUREDESIGNOFCOMPUTERAIDEDFIXTUREDESIGNCAFDSYSTEMSKEYWORDSFIXTUREDESIGN,COMPUTERAIDEDFIXTUREDESIGN,FUNCTIONMODELING,CAD/CAM,INFORMATIONINTENSIVEFUNCTIONMODELSINTRODUCTIONFIXTUREDESIGNISACOMPLEXTASKTHATHASBEENVIEWEDBYINDUSTRIALPRACTITIONERSANDRESEARCHERSASAVITALLINKBETWEENDESIGNANDMANUFACTURINGACTIVITIESSAKURAI1990SENTHILKUMAR,SUBRAMANIAM,SEOW1997COMPUTERAIDEDFIXTUREDESIGNCAFDISACRUCIALTASKWHOSEREALIZATIONWILLENABLETHEINTEGRATEDACCOMPLISHMENTOFCOMPUTERAIDEDDESIGNCADANDCOMPUTERAIDEDMANUFACTURINGCAMACTIVITIESINMODERNMANUFACTURINGENVIRONMENTSTHEREHAVEBEENNUMEROUSEFFORTSTOAUTOMATEFIXTUREDESIGNACTIVITIESANDDEVELOPCAFDMETHODSFORROTATIONALANDPRISMATICPARTSMANUFACTURINGSEEREFERENCESL22,2439,41,42,45,46HOWEVER,THEREHASBEENALACKOFEFFECTIVECAFDTECHNIQUESTOFILLTHEVOIDBETWEENCADANDCAM,ANDAUTOMATEDFIXTUREDESIGNTECHNIQUESCONTINUETOBETHEFOCUSOFMANUFACTURINGRESEARCHEFFORTSTHEREISANEEDTOBETTERUNDERSTANDTHECOMPLEXTASKSANDSUBTASKSWITHINTHEFIXTUREDESIGN58ACTIVITYBYDEVELOPINGAFUNCTIONMODELOFOVERALLACTIVITIESSUCHAMODELWOULDNOTONLYHELPTHEUNDERSTANDINGOFTHECOMPLEXFUNCTIONSANDTASKACCOMPLISHMENTSWITHINFIXTUREDESIGNBUTWOULDRESULTINAMODELOFWHATWASBEINGACCOMPLISHEDBYTHEVARIOUSFUNCTIONSINGENERAL,AFUNCTIONMODELCANBEDESCRIBEDASAREPRESENTATIONOFACTIVITIESWITHINATARGETFOCUSAREAORSYSTEMANDTHERELATIONSHIPSBETWEENTHEMAFUNCTIONMODELCANALSOENABLEUNDERSTANDINGOFTHEIMPACTANDROLEOFVARIOUSINFORMATIONINPUTSANDCONTROLSINTHEACCOMPLISHMENTOFACTIVITIESPASTEFFORTSHAVENOTEMPHASIZEDTHEUSEOFFORMALMODELSORREPRESENTATIONSASABASISFORDESIGNINGANDDEVELOPINGCAFDSYSTEMSTHERESEARCHACTIVITYDISCUSSEDHEREEXPLORESTHEROLEOFINFORMATIONINTENSIVEFUNCTIONMODELSIIFM,WHICHCANBEAVALUABLETOOLINOBTAININGABETTERUNDERSTANDINGOFCOMPLEXACTIVITIESANDTASKSINADOMAINSUCHASFIXTUREDESIGNFURTHER,THESEMODELSPROVIDEASTRUCTUREDBASISOFCOMMUNICATIONTOCONCURRENTENGINEERINGCETEAMS,WHOWILLBEIMPACTEDBYANDWHOIMPACTTHEACTIVITIESWITHINFIXTUREDESIGNFUNCTIONMODELSCANALSOBEUSEDASAREQUIREMENTSDEFINITIONMAPBYSOFTWAREENGINEERSWHOSUPPORTTHEIMPLEMENTATIONOFSOFTWARESYSTEMSTHATACCOMPLISHCAFDAFORMALLYSTRUCTUREDMODELCANMOREEFFECTIVELYCONVEYTHECOMPLEXRELATIONSHIPSANDDEPENDENCIESAMONGSUBACTIVITIESOTHERENGINEERSSUCHASPRODUCTDESIGNERSORMACHINISTSINVOLVEDINTHELIFECYCLEOFAPRODUCT,ANDWHOARENOTFAMILIARWITHFIXTUREDESIGNACTIVITIES,CANGETABETTERUNDERSTANDINGOFTHEINTERRELATIONSHIPSANDTHENEEDFORFEEDBACKANDTIMELYCOMMUNICATIONAMONGTHEIRRESPECTIVECETEAMSBEFOREANINFEASIBLEDESIGNIDEAPROGRESSESTOWARDOTHERDOWNSTREAMJOURNALOFMANUFACTURINGSYSTEMSVOL21/NO12002ACTIVITIESTHEPOWEROFIIFMSLIESINTHEIRABILITYTODESCRIBEWHATCANORWILLBEACCOMPLISHEDBYASYSTEM,HUMANTEAMMEMBERS,ANDOTHERRESOURCESIIFMSEXPLICITLYCAPTUREINTRICATERELATIONSHIPSBETWEENINFORMATIONSOURCES,BOTTLENECKORIENTEDCONSTRAINTSFOREXAMPLE,AVAILABILITYOFDATAORSOMEOTHERINTERNALATTRIBUTE,ANDTHESOFTWAREORHARDWAREMECHANISMSTHATWORKTOGETHERTOACCOMPLISHAGIVENACTIVITYINTODAYSINFORMATIONTECHNOLOGYORIENTEDMANUFACTURINGENVIRONMENT,THEDESIGNOFMANUFACTURINGRELATEDSOFTWARESYSTEMSMUSTBEACCOMPLISHEDTAKINGINTOCONSIDERATIONSUCHINFORMATIONATTRIBUTESTHATARECAPTUREDINIIFMSFIXTUREDESIGNISACOMPLEXTASK,ANDUNDERSTANDINGTHERELATIONSHIPSEXPLICITLYANDBUILDINGANIIFMOFTHESEATTRIBUTESLAYSTHEFOUNDATIONFORIMPLEMENTINGEFFECTIVECAFDAPPROACHESITALSOPROVIDESACOMMONLANGUAGEFORREASONINGASPECIFICAPPROACH,ENABLESCETEAMMEMBERSTOUNDERSTANDANDCOMMUNICATEPOTENTIALPROBLEMSININFORMATIONAVAILABILITYMOREEFFECTIVELY,ANDPROPOSESWAYSTOACCOMPLISHACORESETOFACTIVITIESINAMOREINTEGRATEDMANNERUSINGTHEFUNCTIONMODELOFFIXTUREDESIGNACTIVITIES,APRELIMINARYVERSIONOFACAFDSYSTEMCALLEDTAMILTOWARDSAMANUFACTURINGINTEGRATIONLINKHASBEENDEVELOPEDCECIL2001THEIIFMPROVIDEDAFUNDAMENTALBASISTOUNDERSTANDANDMAPCOMPLEXRELATIONSHIPS,STUDYINFORMATIONFLOW,ANDTHENDESIGNANDBUILDASYSTEMTOAUTOMATEFIXTUREDESIGNACTIVITIESIDEF0METHODOLOGYWASUSEDTOBUILDTHEIIFMTHEIDEF0MODELRESULTINGFROMTHEUSEOFTHISMETHODOLOGYPROVIDEDAFOUNDATIONFORUNDERSTANDINGTHECOMPLEXACTIVITIESINFIXTUREDESIGNANDFACILITATEDTHEDEFINITIONOFACTIVITIESANDINFORMATIONSURROUNDINGTHESEFUNCTIONSINOTHERINITIATIVES,THEIDEF0METHODHASBEENUSEDASAPOWERTILMODELINGTOOLFORANALYSIS,SPECIFICATION,ANDDESIGNOFMANUFACTURINGANDOTHERSYSTEMSCECIL1995MAYER,KEEN,BLINN1990THEFOURBASICATTRIBUTESMODELEDFOREACHACTIVITYANDSUBTASKSINCLUDEINPUTS,CONTROLS,OUTPUTS,ANDMECHANISMSTERMEDICOMS,SEEFIGUREITHEIDEF0METHODINCLUDESAGRAPHICALLANGUAGETHATENABLESTHEUSERTODESCRIBETHEACTIVITIESBEINGMODELEDINAPOWERFULHIERARCHICALMANNERTHEROOTORHIGHESTLEVELINTHISHIERARCHICALSTRUCTUREHASLOWERLEVEL,ORCHILDREN,NODESTHATDETAILTHEFUNCTIONAACTIVITYBEINGMODELEDATRAVERSALOFTHISHIERARCHYUNFOLDSTHEDETAILSOFTHECHILDRENACTIVITIESANDTHEOBJECTSTHATFORMTHERELATIONSBETWEENTHESEACTIVITIESINPUTCONTROLMECHANISMOUTPUTFIGUREIICOMATTRIBUTESILLUSTRATEDINANIDEF0MODELFUNCTIONMODELDEVELOPMENTANDDESCRIPTIONSTHEIDEF0FUNCTIONMODELDISCUSSEDWASBUILTAFTERSTUDYINGTHEACCOMPLISHMENTOFFIXTUREDESIGNACTIVITIESBYEXPERTFIXTUREDESIGNERSANDPROCESSPLANNERSKNOWLEDGEANDINFORMATIONFROMFIXTUREDESIGN,TOOLDESIGN,ANDMETALCUTTINGHANDBOOKSANDFROMJOURNALPAPERSHASALSOBEENUSEDTODEVELOPAMOREHOLISTICIDEF0MODELADDITIONALDISCUSSIONOFTHEINFORMATIONREPRESENTEDINANIDEF0MODELISPROVIDEDINTHESECTIONENTITLEDIDEF0FUNCTIONMODELOFFIXTUREDESIGNDOMAINEXPERTSINCLUDEDAPROCESSPLANNEREXPERTA,ATOOLENGINEEREXPERTB,ANDANENGINEERINGINSTRUCTOREXPERTCEXPERTAWORKSINAMACHINESHOPANDHASMORETHAN20YEARSOFEXPERIENCEPERFORMINGPROCESSPLANNING,FIXTUREDESIGN,ANDMACHININGINAJOBSHOP,WHICHPRODUCESBOTHROTATIONALANDPRISMATICPARTSEXPERTBISATOOLENGINEERINTHEAUTOMOBILEINDUSTRYWITHADECADEOFINDUSTRIALEXPERIENCEWHODESIGNSJIGSANDFIXTURESFORPARTSUSEDINTHEPRODUCTIONOFCARSANDTRUCKSEXPERTCISAMECHANICALENGINEERINGINSTRUCTORWHOTEACHESFIXTUREDESIGNRELATEDCOURSESANDHADPREVIOUSLYWORKEDASAFIXTUREDESIGNERINTHEAUTOMOBILEINDUSTRYVERBALPROTOCOLANALYSISWASUSEDASTHEMETHODOFACQUIRINGDETAILEDKNOWLEDGEFROMTHEDOMAINEXPERTSAFTERBEINGGIVENAPRODUCTDESIGNANDDESIGNINGTHEFIXTURE,EACHEXPERTPROVIDEDEXPLANATIONSOFALISTOFPOSSIBLEDESIGNSORCONCLUSIONSAFTERTHEEXPERTSCOMPLETEDTHENECESSARYEXPLANATIONS,THEMODELDEVELOPERREVIEWEDTHEDESCRIPTIONOFTHEPROTOCOLORSTEPSUSEDTOARRIVEATTHEFIXTUREDESIGNSANDADDEDMOREDETAILSIFNECESSARYCECIL200059JOURNALOFMANUFACTURINGSYSTEMSVOL21RNO12002ANOTHERPROTOCOLUSEDINKNOWLEDGEACQUISITIONFORTHEFIXTUREDESIGNACTIVITYWASBLINDPROBLEMDISCUSSIONTUTHILL1990FIXTUREDESIGNSFROMANOTHERKNOWLEDGEEXPERT,ASWELLASFROMBOOKSANDPAPERS,WEREUSEDINTHEDISCUSSIONEACHFIXTUREDESIGNEXPERTWASPRESENTEDWITHAPARTDESIGNDESIGNAANDASKEDTODESIGNAFIXTUREFORTHATPARTDESIGNEACHEXPERTSORGANIZATIONOFKNOWLEDGE,THEHYPOTHESESCONSIDEREDTHEINFLUENCEOFVARIOUSFACTORSDURINGANALYSIS,ANDTHEDETERMINATIONOFTHEOVERALLDETAILEDDESIGNWERERECORDEDTHISRECORDEDAPPROACHWASCOMPAREDWITHTHEAPPROACHDESCRIBEDBYOTHERFIXTUREDESIGNEXPERTSFORTHESAMEPARTDESIGNBYCOMPARINGANDCONTRASTINGTHEAPPROACHESOFTHESEFIXTUREDESIGNERS,ABETTERUNDERSTANDINGOFTHEFIXTUREDESIGNACTIVITYWASOBTAINEDTHISTECHNIQUEWASREPEATEDWITHAPPROACHESDETAILEDINBOOKSANDMANUALSNUMEROUSQUESTIONSWEREASKEDTOCLARIFYWHYCERTAINTASKSWEREPERFORMEDANDWHATROLESPECIFICFACTORSORINPUTSPLAYEDINTHEFIXTUREDESIGNTHEINTENTWASTOOBTAINANUNDERSTANDINGOFANALYSISCRITERIAINFIXTUREDESIGNTYPICALQUESTIONSEXPLOREDBYTHEMODELDEVELOPERINCLUDEDWHATTYPESOFINFORMATIONWEREREQUIREDTODETERMINEPROBLEMBOUNDARIESWHATLEVELOFDETAILINTHESOLUTIONORDESIGNWASREQUIREDHOWTODECOMPOSEAPROBLEMINTOSUBPROBLEMSANDWHATTYPESOFANALYTICALANDHEURISTICRULESWERETYPICALLYUSEDORREQUIREDTOVALIDATETHEFINALDESIGNSOLUTIONWITHOUTHAVINGTOBUILDANACTUALFIXTUREOFTHEDEVELOPEDFIXTUREDESIGNTHEDOMAINEXPERTSCONCLUSIONSWEREANALYZEDFURTHERBYPOSINGWHATIFSCENARIOSTOUNDERSTANDMOREABOUTTHEPROBLEMSOLUTIONAFOLLOWUPPOSTSESSIONDISCUSSIONHELPEDEXPLOREEACHFACTORANDATTRIBUTETHATSEEMEDTOINFLUENCEDEVELOPMENTOFTHEPROBLEMSOLUTIONTHISDISCUSSIONHELPEDESTABLISHINDIVIDUALCONTRIBUTIONSOFTHEVARIOUSINPUTSORFACTORSSUCHASTOLERANCES,FEATUREATTRIBUTES,ETCTOTHEOVERALLFIXTUREDESIGNACTIVITYIDEF0FUNCTIONMODELOFFIXTUREDESIGNINTHISSECTION,THEIDEF0MODELOFFIXTUREDESIGNISPRESENTEDANDABRIEFDISCUSSIONOFEACHACTIVITYPERFORMEDINFIXTUREDESIGNISPROVIDEDINGENERAL,ANIDEF0MODELINCLUDESASUMMARYPURPOSE,VIEWPOINT,CONTEXT,DECOMPOSITIONDIAGRAMS,DESCRIPTIONSOFTHEMODELEDACTIVITIES,ANDAGLOSSARYFIXTUREDYIGNPRINCIPLES/CONCEPTSPRODUCTDESIQNDATAINITIALRAWWORKPIECESPECIFICATIONSTENTATIVEMACHININGSEQUENCESDEVELOPFIXTUREDESIGNSTFIXTUREDESIGNERFIGURE2AOLEVELDIAGRAMOFFIXTUREDESIGNACTIVITYOFTHEICOMATTRIBUTESCAPTUREDINTHEMODELINTHISPAPER,THETOPLEVELANDDECOMPOSITIONDIAGRAMSAREILLUSTRATEDINFIGURES2,3,4,6,8,9,AND13THEPURPOSEOFBUILDINGTHISIDEF0MODELWASTOPROVIDEABETTERUNDERSTANDINGOFTHEVARIOUSACTIVITIESANDSUBACTIVITIESANDTASKSPERFORMEDWITHINFIXTUREDESIGNANDCAPTURETHECOMPLEXINTERRELATIONSHIPSAMONGTHESEACTIVITIESANDTHEIRDECOMPOSITIONSTHISFUNCTIONMODELWASUSEDTOBUILDANAUTOMATEDFIXTUREDESIGNSYSTEMTOSERVEASALINKBETWEENCADANDCAMACTIVITIESTHEMODELINGVIEWPOINTWASFROMANINDUSTRIALENGINEERWITHASTRONGBACKGROUNDINBOTHDESIGNANDMANUFACTURINGWHOHASPERFORMEDFIXTUREDESIGNACTIVITIESANDISFAMILIARWITHFUNDAMENTALFIXTUREDESIGNTASKSTHECONTEXTFORBUILDINGANYIDEF0FUNCTIONMODELISPROVIDEDINADIAGRAMREFERREDTOASACONTEXTDIAGRAMSHOWNINFIGURE1THESPECIFICCONTEXTLEVELDIAGRAMFORTHEMODELEDFIXTUREDESIGNACTIVITIESISSHOWNINFIGURE2FORTHEFIXTUREDESIGNACTIVITIES,INPUTSASSUMEDTOBEAVAILABLETOTHEFIXTUREDESIGNERINCLUDEPRODUCTDESIGNINFORMATIONSUCHASDESIGNDRAWINGS/CADMODELS,TOLERANCESPECIFICATIONS,ETCANDWORKPIECEMATERIALINPUTSCANBEREALOBJECTSORDATANEEDEDTOPERFORMALTHEFIXTUREDESIGNERIDENTIFIESTHETOLERANCEPLANESORDATUMREFERENCEPLANESFOREACHFEATURETHISACTIVITYISAPRECURSORTOIDENTIFYINGTHEDATUMORFACEF2FIGURE5EXAMPLEOFAPARTDESIGNDECOMPOSITIONOFACTIVITYA2ANALYZEMACHININGREQUIREMENTSREFERENCEPLANESINEACHSETUP,WHICHISPERUNDERTHECATEGORYANALYZEMACHININGFORMEDLATERFIGURE5ILLUSTRATESANEXAMPLEOFAREQUIREMENTSFIGURE6THEFIRSTACTIVITYINVOLVESPARTDESIGNWITHTOLERANCESUNITSINMMANDTWOIDENTIFYINGMACHININGREQUIREMENTSA21THEFIXFEATURESSTEPANDABLINDHOLETHEDATUMPLANESTUREDESIGNERSTUDIESTHEMACHININGREQUIREMENTSOFGIVENAREFACESF5,F7,ANDFLEACHFEATUREINTHEGIVENPARTDESIGNANYMACHININGMLDECOMPOSITIONOFANALYZEMACHININGREQUIREMENTSACTIVITYA263JOURNALOFMANUFACTURINGSYSTEMSVOL21MO12002CONSTRAINTTHATMAYINFLUENCETHEDESIGNOFTHEFIXTUREISIDENTIFIEDTHEMACHININGCONSTRAINTSINFLUENCINGFIXTUREDESIGNDEPENDONTHETYPEOFFEATUREBEINGMACHINEDANEXAMPLEOFTHISWOULDBEWHETHERTHEMACHININGOFAFEATURESUCHASATHROUGHHOLEORSLOTINFLUENCESTHEDESIGNOFASUPPORTORLOCATORMACHININGATHROUGHHOLEREQUIRESTHATCAREBETAKENWHILEDESIGNINGASUPPORTAKEYASPECTTOBEADDRESSEDISENSURINGTHATTHEMACHINECUTTINGTOOLSUCHASADRILLISABLETODRILLTHROUGHTHEBOTTOMFACEANDCLEARTHEBOTTOMFACEINREFERENCETHISWOULDREQUIRETHATTHESUPPORTDEVICEUSEDBEDESIGNEDTOPROVIDEARELIEFFORTHEDRILLTOOLTOCLEARTHEBOTTOMFACEWHILEMACHININGTHETHROUGHHOLEINREFERENCETHEMACHININGOFASLOTORANYOTHERFEATURETHATSTRADDLESTWOFACESOROCCURSACROSSTWOFACESALSONEEDSTOBESTUDIEDMACHININGOFSLOTSNECESSITATESASIDEHEIGHTCLEARANCETOALLOWTHEMILLINGCUTTERTOMACHINETHEENTRANCEOFTHESLOTTHEFACEPOSSESSINGTHEENTRANCEOFASLOTCANBEUSEDASALOCATINGORADDITIONALLOCATINGSURFACEASLONGASTHELOCATINGDEVICEDOESNOTOBSTRUCTTHEMACHININGOFTHESLOTFIGURE7ISSUESRELATEDTOTHEMACHININGOFFEATURESAREIDENTIFIEDINTHISACTIVITYANDAREUSEFULWHENTHEFIXTUREDESIGNERPERFORMSDETAILEDLOCATOR,SUPPORT,ANDCLAMPDESIGNINTHELATERSTAGESTHENEXTACTIVITY,IDENTIFYCHIPREMOVALREQUIREMENTSASINDICATEDINFIGURE6,ISCLOSELYRELATEDTOACTIVITYA21THEACCUMULATIONOFCHIPSDURINGMACHININGOFFEATURESSUCHASTHROUGHHOLESNEEDSTOBEADDRESSEDTHETYPEOFMACHINETOOLUSEDALSOINFLUENCESTHECHIPACCUMULATIONPROBLEMFOREXAMPLE,IFAMACHINETOOLSUCHASAGUNDRILLISUSED,CHIPACCUMULATIONISNOTAPROBLEMBECAUSEAGUNDRILLCOLLECTSTHECHIPSWITHTHEUSEDCOOLANTDURINGDRILLINGANDDISPOSESTHEMUSINGASUCTIONMECHANISMWHENOTHERDRILLTOOLSAREUSED,THEFIXTUREDESIGNERHASTOINCORPORATEARELIEFDESIGNINTHESUPPORTDEVICETOMINIMIZETHEACCUMULATIONOFCHIPSDURINGMACHININGANOTHERACTIVITYRELATESTOGROUPINGPOSSIBLEOPERATIONSA23INFIGURE6THEMAJORMACHININGCONSTRAINTADDRESSEDBYTHEFIXTUREDESIGNERISINTHEGENERATIONOFSETUPSTHEGOALINTHISACTIVITYISTOENABLETHEMACHININGOFASMANYFEATURESASPOSSIBLEINASETUPTHEMAJORCONSTRAINTISTHECAPABILITYOFTHEMACHINESAVAILABLEONTHESHOPFLOORTENTATIVELYSPECIFIEDBYTHEPROCESSPLANNERSEEFIGURE2VARIOUSSETUPSTOMACHINETHEFEATURESONTHEHORIZONTALDIMENSIONSOFLOCATORSHOULDALLOWFORMACHINETOOLCLEARANCETOMACHINETHESLOTFIGURE7ANALYZINGMACHININGREQUIREMENTSGIVENPARTDESIGNAREGENERATEDBASEDONTHEDIRECTIONOFMACHINING,THEPROCESSSEQUENCE,ANDTHEMACHININGCAPABILITIESOFAVAILABLEMACHINESONTHESHOPFLOORTHEFIXTUREDESIGNERIDENTIFIESTHEMACHININGDIRECTIONSTOPRODUCEEACHOFTHEFEATURESONAGIVENPARTDESIGNFEATURESTHATPOSSESSTHESAMEMACHININGDIRECTIONTHATCANBEMACHINEDONANASSIGNEDMACHINEPERTHEPROCESSSEQUENCEPROVIDEDAREGROUPEDTOGETHERANDFORMONESETUPFORTHEPARTDESIGNSHOWNINFIGURE5,BOTHOFTHEFEATURESCANBEMACHINEDINTHESAMESETUPTHELASTACTIVITYOFA2SEEFIGUREISTOIDENTIFYPOTENTIALREFERENCEPLANESA24AFTERDETERMININGTHEVARIOUSMACHININGSETUPS,THEFIXTUREDESIGNERATTEMPTSTOIDENTIFYREFERENCEPLANESORFEATURESFOREACHSETUPTHEGUIDINGTHEMEINTHISACTIVITYISTOACCURATELYLOCATEVARIOUSFEATURESTOBEMACHINEDINASETUPINGENERAL,FIXTUREDESIGNERSPREFERTHEUSEOFPREMACHINEDORPREEXISTINGTHROUGHHOLESANDAPAIROFADJACENTPERPENDICULARFACESDOWELPINSINSERTEDINTOTHROUGHHOLESPOSITIONTHEWORKPIECEACCURATELYANDHOLDTHATPOSITIONWELLDURINGMACHININGAPAIROFFLATPLATELOCATORSBUTTINGAGAINSTACORRESPONDINGPAIROFRIGHTANGLEDSURFACESRIGIDLYENSURESACCURATEWORKPIECELOCATIONDURINGMACHININGFORTHEFEATURESTOBEMACHINEDINFIGURE5,FACES1,5,AND7CANSERVEASPOTENTIALREFERENCEPLANESDECOMPOSITIONOFACTIVITYA3PERFORMSKELETALFIXTUREDESIGNTHEACTIVITYPERFORMINGASKELETALFIXTUREDESIGNACTIVITYA3INFIGURE3CANBEDECOMPOSEDASSHOWNINFIGURE8THETERMSKELETALFIXTUREDESIGNREFERSTOTHEGENERALDESIGNIDEATOSUPPORT,LOCATE,ANDCLAMPAWORKPIECEINASETUPFORINSTANCE,AFIXTUREDESIGNER64JOURNALOFMANUFACTURINGSYSTEMVOL21/NO12002MLFIGURE8DECOMPOSITIONOFPERFORMSKELETALFIXTUREDESIGNA3MAYINITIALLYDECIDEON1USINGASUPPORTAGAINSTTHEBOTTOMFACEOFAPART2USINGAPREMACHINEDHOLETOLOCATEALLFEATURESTOBEMACHINEDINTHATSETUPAND3ADOPTINGASIDECLAMPINGMETHODTOHOLDAWORKPIECETHISINITIALDESIGNISBASEDONTHEFIXTUREDESIGNERSUNDERSTANDINGOFTHEFEATURESTOBEPRODUCED,THEDATUMPLANESINTHATSETUP,ANDTHENATURE,OFTHEBASEANDSIDEFACESTHATIS,ARETHEYPLANARANDDOTHEYPOSSESSENOUGHAREAFORACLAMPTOBEUSED,AMONGOTHERISSUESASMENTIONEDEARLIER,EXPERIENCEDFIXTUREDESIGNERSUSUALLYFOCUSONTHEDETAILEDFIXTUREDESIGNWITHOUTDEVELOPINGASKELETALFIXTUREDESIGNTHEDOMAINEXPERTSOPINEDTHATDURINGTHEIRINITIALYEARSTHEYPERFORMEDSKELETALFIXTUREDESIGNBEFOREDETAILINGTHEDESIGNHOWEVER,ASTHEIREXPERIENCEINCREASEDTHEYBECAMEMORESKILLEDATPRODUCINGAFEASIBLEFIXTUREDURINGTHEIRFIRSTATTEMPTANDGRADUALLYSTOPPEDDEVELOPINGTHESKELETALFIXTUREDESIGNALTOGETHERASINDICATEDBYACTIVITIESA31,A32,ANDA33INFIGURE8,OTHERFIXTUREDESIGNERSPREFERAMOREORGANIZEDAPPROACHTHEYINITIALLYFORMAMENTALPICTUREOFEACHOFTHESUPPORTING,LOCATING,ANDCLAMPINGTECHNIQUESTHEYTHINKAREFEASIBLETOHOLD,SUPPORT,ANDLOCATETHEWORKPIECEDURINGMACHININGCECIL2000,CECIL1995AGENERALOUTLINEOFTHEFIXTUREISPRODUCEDAFTERDISCARDINGINFEASIBLEDESIGNSORRESOLVINGCONFLICTINGDESIGNPROBLEMSASINA34CONFLICTINGDESIGNPROBLEMSINCLUDEISSUESSUCHASDETERMININGWHETHERTHETENTATIVELYSELECTEDDOWNCLAMPINGMETHODINA33AGREESWITHTHELOCATIONAPPROACHINA32,SUCHASUSINGARADIALLOCATIONTECHNIQUEIFTHEYAREINFEASIBLE,THENTHISCONFLICTISRESOLVEDITERATIVELYASINDICATEDBYTHEFEEDBACKLOOPANALYSISFEEDBACKFROMACTIVITYA34ASINDICATEDINACTIVITYA3,ONEOFTHECONTROLLINGINFLUENCESISTHETERMFIXTURINGDESIGNPRINCIPLESTHISREFERSTOTHEEMBEDDEDFIXTURINGKNOWLEDGEOFTHEDESIGNERINCLUDINGHEURISTICSANDEXPERTISEGAINEDINTHISAREAWHENPERFORMINGTHEFIXTUREDESIGNTASKKNOWLEDGEOFTHEFUNDAMENTALSOFFIXTUREDESIGN,COUPLEDWITHTHEHEURISTICBASE,ISANIMPORTANTINFLUENCEORCONTROLLINGFACTORDURINGTHE65JOURNALOFMANUFACTURINGSYSTEMSVOL21MO12002RGUREYDECOMPOSITIONOFDETAILANDCONSOLIDATEFIXTUREDESIGNA4ACCOMPLISHMENTOFTHEFIXTUREDESIGNSUCHKNOWLEDGEINCLUDESIDENTIFYINGTHEPREFERREDCHOICEOFLOCATINGSURFACESANDWHETHERTHEREISANEEDFORRADIALLOCATION,FAMILIARITYWITHDIFFERENTCLAMPINGMETHODSRANGINGFROMDOWNCLAMPINGTOSIDECLAMPING,ANDSOONDECOMPOSITIONOFACTIVITYA4DETAILANDCONSOLIDATEFIXTUREDESIGNACTIVITYA4,WHICHISTODETAILANDCONSOLIDATETHEFIXTUREDESIGN,ISDECOMPOSEDINTOFOURSUBACTIVITIESASINFIGURE9PERFORMSUPPORTDESIGNINTHEFIRSTSUBACTIVITYESTABLISHSUPPORTPLANEANDSELECTSUPPORTA41,THEFIXTUREDESIGNERDETERMINESTHESUPPORTFACEINEACHSETUPANDSELECTSTHETYPEOFSUPPORTDEVICETOBEUSEDINTHEFIXTUREINFLUENCESONTHISACTIVITYINCLUDEPARTDESIGN,TYPEOFFEATURETOBEMACHINEDINTHATSETUP,ANDMACHININGCONSTRAINTSIFMACHININGISTOBEPERFORMEDALONGAZAXIS,THENTHEFIXTUREDESIGNERPREFERSTOUSEAFLATSURFACEWHOSEOUTERGEOMETRICALENVELOPEALONGTHEXYAXISCONTAINSGEOMETRICALPROFILESOFTHEFEATURESTOBEMACHINEDINTHATSETUPFIGUREIOTHISINCREASESTHESTABILITYOFTHEWORKPIECEDURINGMACHININGWHICHISASUPPORTDESIGNHEURISTICIFATHROUGHHOLENEEDSTOBEDRILLEDINTHATSETUP,THENTHEMACHININGCONSTRAINTSINFORMATIONWILLINFLUENCETHEFIXTUREDESIGNERTOSELECTAFLATPLATEWITHARELIEFINCORPORATEDINITINFIGURE10,ASUPPORTBLOCKWITHARELIEFENABLESTOOLCLEARANCEDURINGTHEDRILLINGOFATHROUGHHOLEPERFORMLOCATORDESIGNTHESECONDSUBACTIVITYINA4FIGURE9ISTOESTABLISHLOCATIONPLANESANDSELECTLOCATORSA42THEFIXTUREDESIGNERUSESTHEIDENTIFIEDREFERENCEPLANE,PARTDESIGNINFORMATION,ANDLOCATIONDESIGNHEURISTICSGAINEDFROMHISORHEREXPERIENCETODETERMINEAFEASIBLELOCATIONFACEONTHEWORKPIECETHELOCATIONDEVICEISTHENSELECTEDBASEDONTHE66JOURNALOFMANUFACTURINGSYSTEMSVOL21MO12002VETHUS,ASUPPORTPLATEOFAL