JIT & Lean Manufacturing精益生产

Just-In-TimeandLeanManufacturingOverview•TheJust-in-TimeManufacturingPhilosophy•PrerequisitesforJITManufacturing•ElementsofJITManufacturing•BenefitsofJITManufacturing•SuccessandJITManufacturing•JITinServices•Wrap-Up:WhatWorld-ClassCompaniesDoAPICSDefinitionofJIT“Aphilosophyofmanufacturingbasedonplannedeliminationofwasteandcontinuousimprovementofproductivity……”APICSDefinitionofJIT“TheprimaryelementsofJust-in-Timeare:–tohaveonlytherequiredinventorywhenneeded;–toimprovequalitytozerodefects;–toreduceleadtimesbyreducingsetuptimes,queuelengths,andlotsizes;–toincrementallyrevisetheoperationsthemselves;–andtoaccomplishthesethingsatminimumcost”.JITSynonyms•IBM-ContinuousFlowManufacturing•HP-StocklessProduction-RepetitiveManufacturingSystem•GE-ManagementbySight•Motorola-ShortCycleManufacturing•Japanese-TheToyotaSystem•Boeing-LeanManufacturingAPICSDefinitionofLeanManufacturing“Aphilosophyofproductionthatemphasizestheminimizationoftheamountofalltheresources(includingtime)usedinthevariousactivitiesoftheenterprise.Itinvolves:–…identifyingandeliminatingnon-value-addingactivities,–…employingteamsofmulti-skilledworkers,–…usinghighlyflexible,automatedmachines”•AmericanProductionandInventoryControlSociety(APICS)isanorganizationforprofessionalsworkinginthefieldofOperationsManagementTraditionalViewofManufacturing•Keyobjectivewastofullyutilizecapacitysothatmoreproductswereproducedbyfewerworkersandmachines•How?Withlargequeuesofin-processinventorywaitingatworkcenters•Workersandmachinesneverhadtowaitforproducttoworkon,socapacityutilizationwashighandproductioncostswerelow•Result:Productsspentmostoftheirtimeinmanufacturingjustwaiting,anarrangementthatisunacceptableintoday’stime-basedcompetitionJITPhilosophyTime-BasedCompetition•Itisnotenoughforfirmstobehigh-qualityandlow-costproducers•Today,theymustalsobefirstingettingproductsandservicestothecustomerfast•Tocompeteinthisnewenvironment,theorder-to-deliverycyclemustbedrasticallyreduced•JITistheweaponofchoicetodaytoreducetheelapsedtimeofthiscycleOrder-to-DeliveryCycleDistri-butionandCustomerServiceCusto-merPlacesOrderOrderEntryEngi-neeringDesignSched-ulingManufacturingLeadTimesPurchasingLeadTimesManufacturingCumulativeLeadTimeOrder-to-DeliveryCycleCustomersFinalAssySubSubFabFabFabFabVendorVendorVendorVendorJITLogicJITManufacturingPhilosophy•ThemainobjectiveofJITmanufacturingistoreducemanufacturingleadtimes•Thisisprimarilyachievedbydrasticreductionsinwork-in-process(WIP)•Theresultisasmooth,uninterruptedflowofsmalllotsofproductsthroughoutproduction•Managementphilosophy•PullsystemthoughtheplantWHATITIS•Employeeparticipation•Industrialengineering/basics•Continuingimprovement•Totalqualitycontrol•SmalllotsizesWHATITREQUIRES•Attackswaste•Exposesproblemsandbottlenecks•AchievesstreamlinedproductionWHATITDOES•StableenvironmentWHATITASSUMESJITProductionSuccessfulJITApplications•MostsuccessfulJITapplicationshavebeeninrepetitivemanufacturing,wherebatchesofstandardproductsareproducedathighspeedsandinhighvolumes.•SuccessfuluseofJITisrareinlarge,highlycomplexjobshopswhereproductionplanningandcontrolisextremelycomplicated.•Smaller,lesscomplexjobshopshaveusedJIT,butoperationshavebeenchangedsothattheybehavesomewhatlikerepetitivemanufacturing.ElementsofJITManufacturing•Eliminatingwaste•Enforcedproblemsolvingandcontinuousimprovement•PeoplemakeJITwork•TotalQualityManagement(TQM)•Parallelprocessing•Kanbanproductioncontrol•JITpurchasing•Reducinginventories•Workingtowardrepetitivemanufacturing(1)Wastefromoverproduction(2)Wasteofwaitingtime(3)Transportationwaste(4)Inventorywaste(5)Processingwaste(6)Wasteofmotion(7)WastefromproductdefectsWaste--OperationsJIT:APullSystem•Inapushsystem,suchasanMRPsystem,welookatthescheduletodeterminewhattoproducenext•Inapullsystem,suchasJIT,welookonlyatthenextstageofproductionanddeterminewhatisneededthere,andthenweproduceonlythat•AsRobertHallstates,“Youdon’tnevermakenothingandsenditnoplace.Somebodyhasgottocomeandgetit”ChangesRequiredforJIT•JITrequirescertainchangestothefactoryandthewayitismanaged:–Stabilizeproductionschedules–Makethefactoriesmorefocused–Increaseworkcentercapacities–Improveproductquality–Cross-trainworkers–Reduceequipmentbreakdowns–Developlong-termsupplierrelationsCapacityUtilization102030405060708090100301020%CapacityUtilization60ProductionLeadTimes(days)4050TraditionalManufacturingJITManufacturingIncreasingProductionCapacityReducesManufacturingLeadTimes•Onlyslightincreasesinproductioncapacitiescanleadto:–Significantreductionofmanufacturingleadtimes–Significantreductionofwork-in-processinventory•Queuingtheorycanbeusedtoanalyzewaiting-lineproductionproblems•Weknowfromqueuingtheorythattheaveragetimeinthesystem(manufacturingleadtime)is:•Ifwehaveanaverageleadtimeinmind,wecansolvefortherequiredproductionrate:NecessaryProductionCapacity1()st1stWork-in-ProcessInventoryWealsoknowfromqueuingtheorythattheaveragenumberofjobsinthesystem(work-in-processinventory)is:()snExample:NecessaryProductionCapacityAproductionmanagerbelievesreducingthefirm’smanufacturingleadti