精益生产的定义一些概念和实际问题外文翻译Word文档下载推荐.docx
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someconceptualandpracticalissues
Discriminantvalidityoflean
SowhatisthenthedifferencebetweenTQMandleanproduction?
InthefollowingsectionLeanandTQMarecomparedbasedontheanalysismadebyHackmanandWageman(1995).Thediscussionisdonewiththreedifferentaspects;
basicassumptions,changeprinciplesandinterventions:
Basicassumptions
Quality.Inlean,qualitydoesnotreceivethesameamountofattentionasintheTQMliterature.Themainfocusintheleanliteratureisonjust-in-time(JIT)production.JITisassumedtodecreasetotalcost,aswellashighlightproblems.Thisisdonethroughreducingtheresourcesinthesystem,sothatbuffersdonotcoveruptheproblemsthatarise.Intheshort-termperspective,thereductionofresourcesimpliesadirectreductionofcost.Inthelongrun,thereductionandsubsequenteliminationofbuffersisassumedtohighlighttheproblemsthatexistinproduction,thusbeingavitalsourceofcontinuousimprovement(e.g.Shingo,1984;
Ohno,1988;
Krafcik,1988Acommonopinionisthatthepurposeofleaniswasteelimination. ).Theliteraturereviewdoesnotshowsupportforthisbeingtheverypurpose,butwasteeliminationisdefinitelyanimportantaspectoftheconcept.Someauthorsarguethatwasteisreducedinordertoincreasethevalueforthecustomer(e.g.Dennis,2002;
Bicheno,2004),whereasothersarguethatitisastrategyforreducingcost(e.g.Ohno,1988;
Monden,1998).ReducingwasteisalsoasignificantpartofTQM,butunderthebannerofpoor-quality-costs(seeHackmanandWageman,1995;
Sö
rqvist,1998).AmajordifferencebetweenTQMandleaninthisaspectistheprecisionindefiningwaste.Inthemajorityoftheleanliterature,wasteormudaisbasedonthesevenforms[1]definedbyOhno(1988),whereasTQMhasaverygeneraldefinitionofpoor-quality-costs,includingeverythingthatcouldbeeliminatedthroughimprovement(Sö
rqvist,1998).
Employeesandthequalityoftheirwork.Onemajorcritiqueoftheleanconceptisthatitisgenerallyweakconcerningtheemployees”perspective.Theproponentsofleanproductionusuallyhaveastronginstrumentalandmanagerialperspective,discussingemployeesintermsofcomponentsintheproductionsystem(seeKamata,1982;
Berggren,1992,1993Theextensive ).discussionaboutjidokaandpokayokeintheleanliteraturesuggeststhatemployeescannotbetrustedtoproducegoodquality,thuscreatinganecessityforremovingthepossibilityofhumanerrorfromthesystem.
Organizationsassystems.OnethingthatleanandTQMhaveincommonisseeingtheorganizationasasystem(seeWomackandJones,2003;
Bicheno,2004).Butthereisaslightdifferenceinperspectivebetweenthetwoconcepts.WhereasTQMhasastrongfocusontheinternalstructureandintegrationofdepartmentswithintheorganization,leanstressesasupplychainperspective,seeingtheinternalproductionoperationsasapartofavaluestreamfromthesub-supplierstotheendcustomer(e.g.RotherandShook,1998;
JonesandWomack,2002).
Qualityistheresponsibilityofseniormanagement.ThisisanotherperspectivethatleanandTQMshare,butagainwithsomedifferences.TQM-managersshouldcreatestructuresthatsupporttheemployeesinproducingproductsofhighquality(Deming,1986;
HackmanandWageman,1995).Theideaisthesameinlean,buttherationalefordoingthisseemstobecenteredaroundeliminatingthehumanfactorfromthesystemthroughjidokaandpokayoke.UsingtheterminologyofMcGregor,onecouldarguethatTQMseemstobebasedontheoryY,whereasleanseemstobebasedontheoryX(seeEzzameletal.,2001).
Changeprinciples
Focusonprocesses.Withintheleanconceptthetermvaluestreamisusuallypreferred(WomackandJones,2003).ThetermprocessisusuallyusedatalowerlevelofabstractionthatTQMtheoristswouldcallsub-processesoractivities(seeRiley,1998).Theconceptionthatmanagementshouldanalyzeandimprovetheprocessesandtraintheemployeesisalsosharedbythetwoconcepts.
Managementbyfact.Theliteratureonleandoesnotreallystressthemanagementbyfactsexplicitly.However,thisisimplicitinthedescriptionofleanpractices,manyofwhichareanalyticaltoolsdesignedtohelpachieveJITproduction.AlthoughthisisasharedperspectivebetweenleanandTQM,thereisadifference.WithinTQMtheanalysisofvariabilitythroughusingstatisticaltoolsisacentralconcept(HackmanandWageman,1995).Intheleantradition,thisisnotseenasequallyimportant.Infact,someauthorsargueagainsttheuseofstatisticaltoolsforanalyzingproductionperformance,recommendingalternativetoolssuchasincreasedinspectionandvisualizationofproblems(e.g.Dennis,2002;
Liker,2004).
Learningandcontinuousimprovement.InthewordsofHackmanandWageman(1995)TQMis“pro-learning,withavengeance”(p.330).Thelearningaspectsarenotemphasizedasmuchinliteratureonlean.Asdiscussedabove,theleanliteratureisgenerallyweakeronthehumanbehaviorside,focusingmoreoninstrumentaltechniquesforimprovingsystemperformance.Thereisaclearfocusoncontinuousimprovement,whichimpliesthatsomeformoflearningisrequired.However,thequestioniswhoislearning.TQMisfocusedonstimulatingcreativityandindividualeffortsforimprovement(HackmanandWageman,1995),whereasleanplacesstrongemphasisonthestandardizationofworkandcollectivelearning(NiepceandMolleman,1998;
ThompsonandWallace,1996).
Interventions
Analysisofcustomerrequirements.CustomerfocusisoneofthehallmarksofTQM,whereeveryimprovementshouldbebasedonaninvestigationofthecustomer'
srequirements,whetherthecustomerisinternalorexternal.Theleanconceptdoesnotemphasizecustomerinterests.Someauthorsarguethattheverypurposeofleanistopleasethecustomer(e.g.Dennis,2002),butmethodsforanalyzingcustomerrequirementsareextremelyrareinthereviewedliterature,suggestingthisisnotatypicalleanintervention.
Supplierpartnerships.ThesuppliersareseenasimportantinbothleanandTQM.Bothconceptstressthepointthatlongtermpartnershipsshouldbemadewithsuppliersandthatimprovementsshouldbedoneincollaborationwiththem.Althoughthismatterisnotdiscussedbyallauthorsinthisanalysis,themajorityofthemdo(seeTableI).
Improvementteams.QualitycircleshaveacentralroleinmuchoftheTQMliterature,andcanbeputtouseinproblemsolvingorimprovementactivities.Intheleanliterature,improvementteamsareexplicitlydiscussedbyjustabouthalfofthereviewedauthors.However,theyareoftenimplicatedindiscussionsaboutimprovementactivities.
Scientificmethodsforperformancemeasurementandimprovement.BothTQMandleanemployvariousscientificmethodsforanalysisandevaluationofperformance.However,thesemethodsdiffersignificantly,andthetoolsassociatedwithoneconceptaregenerallynotmentionedinliteratureontheotherone.Thepurposeofmeasurementsalsodiffers.InTQMmeasurementsaredoneinordertoidentifyproblemsandtodocumentimprovement,whereasleantheoristsarguethatmeasurementsshouldbemadeforplanningandsynchronizationpurposes;
e.g.forsettingproductionrate(seeOhno,1988;
Bicheno,2004).
Processmanagementtechniques.Asdiscussedabove,thetermprocessisusedinslightlydifferentwaysbyauthorsonTQMandlean.Intheleanliterature,differenttechniquesarepresentedforbothoverallprocesslevelandindividualactivities.Atanorganizationallevelvaluestreammapping(VSM)canbeusedforhighlightingseveralkindsofproblemsintheprocesses(RotherandShook,1998).Atamoreoperationallevel,differenttime/workstudytechniquesarediscussed,e.g.so-calledspaghetticharts(e.g.Bicheno,2004).
LeanandTQM–samebutdifferent
Ataphilosophicallevel,leanandTQMhavemanyideasincommon,inparticularconcerningcontinuousimprovementandthesystemsperspective.However,atamoreoperationallevel,thetwoconceptsdiffersignificantly.Thefundamentalvaluesofthetwoconceptsarealsoquitedifferent,especiallyregardinghumanisticvalues.
Conclusions
Thereisnoagreedupondefinitionofleanthatcouldbefoundinthereviewedliterature,andtheformulationsoftheoverallpurposeoftheconceptaredivergent.Discomfortingasthismayseemforleanproponents,thereseemstobequitegoodagreementonthecharacteristicsthatdefinetheconcept,leadingtotheconclusionthattheconceptisdefinedinoperationaltermsalone.Formulatingadefinitionthatcapturesallthedimensionsofleanisaformidablechallenge.
AccordingtoHinesetal.(2004)leanisconstantlyevolving,implyingthatany“definition”oftheconceptwillonlybea“stillimage”ofamovingtarget,onlybeingvalidinacertainpointintime.Thismaybeanexplanationtotheapparentdifferencesbetweenauthorsonthesubject.Basedonthis,itishardnottoraisethequestionofwhetheraconsistentdefinitionofleanispossibletoproduce.Also,onecanquestionwhetheradefinitionwillbeusefulatall,regardingtheeverchangingnatureofthetypeofconstructsthatmanagementconceptssuchasTQMandleanare.Nonetheless,attemptshavebeenmadeinthisarticletopresenttheessentialsofleanproductionandconveyitsmostsalientphilosophicalelements,hopefullyclearingupsomeoftheconfusionthatsurroundstheconcept.
LeanisalsosignificantlydifferentfromitsclosestrelativeTQM,leadingtotheconclusionthatleanisamanagementconceptofitsown.TheconclusionfromShahandWard(2003)thatTQMandotherbundlesarepartsofleanisn