CREVIEW（英文版）

AReviewofGoldratt’sTheoryofConstraints(TOC)–lessonsfromtheinternationalliteratureStevenJ.BalderstoneandVictoriaJ.MabinSchoolofBusinessandPublicMana[e-mail],[e-mail]refinalisingthefirstcomprehensivebibliographyontheTheoryofConstraints(TOC)[23]whichistobepublishedbyNorthRiverPress,thepublishersofseveralworksonTOC,mostnotablyEliGoldratt’sseminalworks[11-17],suchasTheGoal,It’sNotLuck,andCriticalChain.Basedonourextensivesearchoftheliterature,thistalkwilldrawonexamplesofapplicationsofTOC,andsummariseimportantfindingsonthetheoryandpracticeofTOC.Althoughinitiallyamanufacturingmethod,TOChasnowdevelopedintoatheoryaboutmanagement:apowerfulsystemicproblemstructuringandproblemsolvingmethodologywhichcanbeusedtodevelopsolutionswithbothintuitivepowerandanalyticalrigour.TOCisincreasinglybeingappliedtosituationsoutsidethemanufacturingcontext,includingdistribution,marketing,projectmanagement,accounting-infact,anysituationinvolvingchangetoasystem.1IntroductionThemainmotivationfortheresearchreportedinthispaperwastherealisationthatTOCisgrowingveryrapidly,andwesimplydidnotknowwhatwas“outthere”;iewhathadalreadybeentackled.Henceourmissiontwoyearsagowastoconductaliteraturesearchtoidentifyrecentworks(mostlypost1990).Thissearchhasculminatedinanannotatedbibliography,whichistobepublishedshortlybyNorthRiverPress[23].AlongsidethisliteratureresearchgrewaMastersthesis,pullingallthismaterialtogether,boththetheoryandthepractice.[2]ThispaperwillfirstbrieflyoutlinethebackgroundtoTOC,andthenreportonthepractice-relatedmaterialfromthesurveyofpublishedapplicationsandthefindings.ReaderswishingtogainthebenefitofafullertreatmentofthismaterialforareviewoftheentireTOCfieldarereferredto[2];whilethosewishingtoobtainacopyofthebibliographyarereferredto[23].Initsbrief20-yearhistory,TOChasdevelopedrapidlyintermsofbothmethodology(seeforexample[6],[8])andareaofapplications(seeforexample,[19],27]).Inthelate1970’s,thefounderoftheTheoryofConstraints(TOC),EliyahuGoldratt,Israeliphysicistturnedbusinessguru,developedarevolutionarymethodforproductionscheduling[10]whichwasinstarkcontrasttoacceptedmethodsavailableatthetime,suchasMRP.CentraltotheTOCphilosophywasthatanyorganisation(orsystem)hasaconstraint(orsmallnumberofconstraints)whichdominatetheentiresystem.Thesecrettosuccesslieswithmanagingtheseconstraints,andthesystemasitinteractswiththeseconstraints,togetthebestoutofthewholesystem.TheDrum-Buffer-Ropeschedulingsystem,togetherwiththegeneralprinciplesespousedinTheGoal,wereelementsofTOCthatbecamepartofsuccessfulmanufacturingmanagement.Evenso,somecompaniesfailedintheirattemptstoadoptOPT,thesoftwarepackagebasedonGoldratt’smethod[10].Suchfailurewasusuallydiagnosedasaninabilityorunwillingnessbytheorganisationtodiscardoldtraditions,andembracethenewphilosophyandthenewmeasuresthatwereconcomitantwithsuccessfuladoption.Themostcommonmeasuresthatneedtobereviewedareaccountingmeasures,asTOCpromotestheuseofglobalsystem-widemeasures,ratherthanlocalmeasures.Themotivationforthisisthatifasystemasawholeistoachieveitsgoal,itisbestforthesystem’sindividualpartstoworkasateamin“sync”ratherthanattheirownindividualspeeds.Giventhatthemajorconstrainttoimprovementwastheresistancetochangingthesemeasures,itisnotsurprisingthereforethatthisisthedirectionthatTOCfollowed,totacklethisbiggestconstrainttoadoption–behaviours.ThustheTOCThinkingProcesseswereborn:asuiteoftoolsthatallowspeopletolearnandusethethinkingprocessesthatenablethemtodeveloptheirownsolutionstocomplexproblems.Thissuiteoftoolsenablesanalysisofasituation,usingtherigourofcauseandeffectthinkingfollowingstrictlogicrules,combinedwiththeintuitionandknowledgeofthepersonsowning,orintimatelyinvolvedwith,theproblem.TheTP’senablemorecomplexproblems(“messes”)tobetackled,andhavemuchincommonwithothersoftsystemsapproachessuchasSSMandSODA/cognitivemapping.Inouropinion,thesethinkingprocessesnowoffermuchtoOR/MSpractitioners(aswellasthemoretraditionalusersfromtheOperationsManagementfield).2TheSurveyTheliteraturesearchhasuncoveredover310itemsonTOC,including32books.Themajorityoftheseweredeveloping/discussingthemethodologyfromatheoreticalviewpoint.ManyclaimsweremaderegardingthebenefitsofTOC.Theseincludedincreasedthroughputs,reducedinventoriesandlead-times,whichinturnwouldleadtohighersales,andimprovedprofits,quality,andcustomersatisfaction.HoweverwefeltitwouldalsobeusefultocollecttogetherandanalysetheactualreporteddataonthebenefitsofTOC,toverifyordisprovetheseclaims.TheliteraturesearchidentifiedoveronehundredcasestudiesorvignettesthatcontainedinformationontheresultsofapplicationsofTOC.NotallcasesorvignettesprovidedquantitativedataontheresultsofapplyingTOC.Intotal,wewereabletocollectquantitativedataontheapplicationofTOCtoseventy-sevendifferentcompanies.Thetypesoforganisationscoveredbythesecasesvariedfromgiantmulti-nationalcorporationsandindustryleaderslikeBoeingandGM,tomilitaryorganisationsliketheUSAirForce,tosmalltownbakeries.ThevastmajorityofTOCapplicationswerein