JIT-32p

1JITISQA459MelliePullman2Just-In-Time(JIT)Defined•JITcanbedefinedasanintegratedsetofactivitiesdesignedtoachievehigh-volumeproductionusingminimalinventories(rawmaterials,workinprocess,andfinishedgoods).•JITalsoinvolvestheeliminationofwasteinproductioneffort.•JITalsoinvolvesthetimingofproductionresources(e.g.,partsarriveatthenextworkstation“justintime”).3TheJapaneseApproachtoProductivity•Eliminationofwaste•Effortsconcentratedonshopfloor•Respectforpeople•Qualityimprovementfocus4WasteinOperations(1)Wastefromoverproduction(2)Wasteofwaitingtime(3)Transportationwaste(4)Inventorywaste(5)Processingwaste(6)Wasteofmotion(7)Wastefromproductdefects5JITDemand-PullLogicCustomersSubSubFabFabFabFabVendorVendorVendorVendorFinalAssembly6MinimizingWaste:FocusedFactoryNetworksFinalAssemblyCoordinationSystemIntegration7TraditionalConveyanceABCSporadicandInfrequentDeliveriesfromIndividualSuppliers8Mixed-LoadDeliveryABCRegularandFrequentDeliveriesfromManySuppliers9MinimizingWaste:GroupTechnology•UsingDepartmentalSpecializationforplantlayoutcancausealotofunnecessarymaterialmovement.SawSawLathePressPressGrinderLatheLatheSawPressHeatTreatGrinder10MinimizingWaste:GroupTechnology•RevisingbyusingGroupTechnologyCellscanreducemovementandimproveproductflow.PressLatheGrinderGrinderA2BSawHeatTreatLatheSawLathePressLathe111MinimizingWaste:UniformPlantLoadingNotuniformJan.UnitsFeb.UnitsMar.UnitsTotal1,2003,5004,3009,000UniformJan.UnitsFeb.UnitsMar.UnitsTotal3,0003,0003,0009,000Supposeweoperateaproductionplantthatproducesasingleproduct.Thescheduleofproductionforthisproductcouldbeaccomplishedusingeitherofthetwoplantloadingschedulesbelow.Howdoestheuniformloadinghelpsavelaborcosts?or12MixedBatchExample•Companyproducesthreeproductswithamixedmodelassemblyline.–Operates16hoursperdayfor250days/yr.–DeterminethemixedmodelMPSforadailybatch.–DetermineminimumbatchMPSandthemixscheduleforaday.ProductsForecasts(year)120,000210,00035,00013Calculations#1#2#3YearForecast20000100005000DailyBatchdivideby250804020HourlyBatchdivideby1652.51.25MinimumBatchMPS421Foreveryunitof#3(minimumbatch),weneedtwiceasmany#2and4timesAsmany#1soforminimumbatch:Produceduringeachdayproduce#1,1,1,1,2,2,3-repeated20times14MixedBatchExample•Companyproducesfourproductswithamixedmodelassemblyline.–Operates8hoursperdayfor250days/yr.–DeterminethemixedmodelMPSforadailyandhourlybatch.–Determinemixscheduleforaday.ProductsForecasts(year)I500II1500III4500IV600015MinimizingWaste:Just-In-TimeProduction•Managementphilosophy•“Pull”systemthoughtheplantWHATITIS•Employeeparticipation•Industrialengineering/basics•Continuingimprovement•Totalqualitycontrol•SmalllotsizesWHATITREQUIRES•Attackswaste•Exposesproblemsandbottlenecks•AchievesstreamlinedproductionWHATITDOES•StableenvironmentWHATITASSUMES16MinimizingWaste:InventoryHidesProblemsWorkinprocessqueues(banks)ChangeordersEngineeringdesignredundanciesVendordelinquenciesScrapDesignbacklogsMachinedowntimeDecisionbacklogsInspectionbacklogsPaperworkbacklogExample:Byidentifyingdefectiveitemsfromavendorearlyintheproductionprocessthedownstreamworkissaved.Example:Byidentifyingdefectiveworkbyemployeesupstream,thedownstreamworkissaved.17MinimizingWaste:KanbanProductionControlSystemsStoragePartAStoragePartAMachineCenterAssemblyLineMaterialFlowCard(signal)FlowWithdrawalkanbanProductionkanban18DeterminingtheNumberofKanbansNeeded•Settingupakanbansystemrequiresdeterminingthenumberofkanbans(orcontainers)needed.•Eachcontainerrepresentstheminimumproductionlotsize.•Anaccurateestimateoftheleadtimerequiredtoproduceacontaineriskeytodetermininghowmanykanbansarerequired.19TheNumberofKanbanCardSetsCSdLk)(1containertheofSizestockSafetytimeleadduringdemandExpectedk=Numberofkanbancardsets(asetisacard)d=AveragenumberofunitsdemandedoversometimeperiodL=leadtimetoreplenishanorder(sameunitsoftimeasdemand)S=SafetystockexpressedasapercentageofdemandduringleadtimeC=Containersize20ExampleofKanbanCardDetermination:ProblemData•Aswitchassemblyisassembledinbatchesof4unitsfroman“upstream”assemblyareaanddeliveredinaspecialcontainertoa“downstream”control-panelassemblyoperation.•Thecontrol-panelassemblyarearequires5switchassembliesperhour.•Theswitchassemblyareacanproduceacontainerofswitchassembliesin2hours.•Safetystockhasbeensetat10%ofneededinventory.21ExampleofKanbanCardDetermination:Calculations3or,75.245(2)(1.1))(1containertheofSizestockSafetytimeleadduringdemandExpectedCSdLkAlwaysroundup!22JITRequirements:DesignFlowProcess•Linkoperations•Balanceworkstationcapacities•Re-layoutforflow•Emphasizepreventivemaintenance•Reducelotsizes•Reducesetup/changeovertime23JITRequirements:ImproveProductDesign•Standardproductconfiguration•Standardizeandreducenumberofparts•Processdesignwithproductdesign•Qualityexpectations24RespectforPeople•Levelpayrolls•Cooperativeemployeeunions•Subcontractornetworks•Invertedpyramidmanagementstyle•Smallgroupinvolvementactivities25JITRequirements:TotalQualityControl•Workerresponsibility•MeasureSQC•Enforcecompliance•Fail-safe(Poke-yoke)methods•Automaticinspection26POKE-YOKEs