InternationalJournalofProductionResearchVol.50,No.6,15March2012,1682–1701DesignofanintegratedqualityassurancestrategyinproductionsystemsDariaBattinia,MaurizioFacciob,AlessandroPersonaaandFabioSgarbossab*aDepartmentofManagementandEngineering,UniversityofPadua,36100Vicenza,Italy;bDepartmentofInnovationinMechanicsandManagement,UniversityofPadua,35131Padova,Italy(Received2July2010;finalversionreceived21October2010)High-qualityofproductsisacriticalissueformanufacturerstomaintaintheircompetitivenessinglobalmarkets.Forthisreason,moreattentionhasbeenpaidbyoperationsmanagersandacademicstothedesignofqualityassurancestrategies,acceptancesamplingplansandinspectionallocationproblems.Inthelastdecades,internationalresearchhasstudiedandintroducedseveralmodelsandapproachestoinvestigatetheseissues.Thepurposeofthispaperistoprovideanewmethodologyfordesigningandselectingcorrectintegratedqualityassurancestrategies,definingcostmodelsforacceptancepoliciesandinspectionstationconfigurations.Generally,high-qualityofitemsisguaranteedbyavoidingdefects,mainlycausedbynon-conformingcomponents,resultingfrominstantaneousandstandardinfantmortality.Thus,anoptimalacceptancepolicyisdefinedinordertoreducetheinstantaneousinfantmortalitydefects.Aclosed-formequationhasbeenintroducedtodetermineeasilyandquicklytheoptimalpercentageofcheckeditems.Furthermore,amoreconvenientinspectionstationconfigurationisdeterminedinordertominimisetheexpectedtotalcost,composedoftesting,inspectionandpenaltycostelements.Theinnovativeconceptofdefectrateasaninspectiontimevariabledependenthasbeenintroduced.Theimpactofdifferenteconomicandsurvivalparametersondesigninginspectionpoliciesisalsoinvestigated.Finally,areal-lifecasestudydemonstratestheapplicabilityofthismethodologyinrealproductionsystemsandseveralconsiderationsarereportedaboutthefutureresearch,thattheauthorswillcarryout.Keywords:qualityassurancestrategy;acceptancepolicy;inspectionallocationproblem;time-dependentdefectrate;costmodels;casestudies1.IntroductionandliteraturereviewOneofthemostimportantproblemsthatcompanieshavebeenfocusingonforthelast20to30yearsisquality.Theincreasingcompetitivenessofmarketsleadsqualitytobecomewidelyregardedasakeyelementforsuccessinbusiness,especiallyinmanufacturingindustries.Fromaproductivepointofview,qualitycanbedefinedasthefractionofgoodsthatareproducedcorrectlyfirsttime.Ingeneralterms,allproductionsystemsaretechnologicallyincapableofguaranteeingthetotalqualityoffinishedproductsandthemainafter-saleservicecostsfortheseitemsaretypicallywarrantyandpenaltycosts,linkedtotheinfantmortalityofproducts.Furthermore,theextensionofglobalsupplychains,suchastheadoptionofsupplierswhoseproductionplantsarebasedindevelopingcountries,inordertoreducepurchasedcomponentcosts,hasresultedinevidentreductionsinthequalityoftheseitems.Fromacustomersatisfactionpointofview,thesedefectsareunacceptableandreduceconfidenceinmanufacturedproducts.Defectsaregenerallyrelatedtodesignandproductionorlowqualityassembledproductsoruseditemsinfinishedproducts.Consequently,adefectinafinishedproductcanbecausedbytwokindsoffault.Thefirstistheinstantaneousinfantmortalitydefect(IIMD).Itoccursattime0whenanitemdoesnotattainseveralrequiredfeatures.Thesecondiscalledthestandardinfantmortalitydefect(SIMD).Thecorrectacceptancepolicypermitsthedetectionofthefirsttypeofdefects(IIMDs),defininghowandhowmanyitemshavetobecheckedduringtheacceptancephase,typicallyusingon–offtests.Next,theappropriateinspectionstationconfigurationallowsthedetectionofdefectsinthesecondgroup(SIMDs).Generally,theobjectiveofinspectionistodetectdefectiveitemsassoonaspossibleandthentoformulateappropriatetreatments.Asaconsequence,oneoftheproblemsischoosingthelocationstoinsertinspectionstationsinsideproductionsystems,atwhichdefectscanbefoundduringthetestinganddefectiveitemstreated.*Correspondingauthor.Email:fabio.sgarbossa@unipd.itISSN0020–7543print/ISSN1366–588Xonline2012Taylor&Francis://(Battinietal.2007,2008,2009a,2009b,2009c,Personaetal.2007,2009).Highqualityofproductsrequiredbycustomershasinvolvedthedefinitionofaqualityassurancestrategy.GeneralsurveysonthisproblemhavebeenintroducedbyRaz(1986)andinterestinglyaddedtobythemorerecentworkofMandrolietal.(2006).Accordingtothelatter,aqualityassurancestrategyaimstoallocatetheeconomicallyappropriatelevelofinspectionactivitiesbetweenacceptancepoliciesandinspectionallocationconfigurations,balancingthevariouscostcomponentsofinspection,repair,replacementresultingfromdetectiontasksandthewarrantypenaltywhenadefectiveproductreachesth