JITDemand-PullLogic(英文版).pptx

JITDemand-PullLogic(英文版).pptx

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JITISQA459MelliePullman1Just-In-Time（JIT）DefinedJITcanbedefinedasanintegratedsetofactivitiesdesignedtoachievehigh-volumeproductionusingminimalinventories（rawmaterials,workinprocess,andfinishedgoods）.JITalsoinvolvestheeliminationofwasteinproductioneffort.JITalsoinvolvesthetimingofproductionresources（e.g.,partsarriveatthenextworkstation“justintime”）.2TheJapaneseApproachtoProductivityEliminationofwasteEffortsconcentratedonshopfloorRespectforpeopleQualityimprovementfocus3WasteinOperations

（1）Wastefromoverproduction

（2）Wasteofwaitingtime（3）Transportationwaste（4）Inventorywaste（5）Processingwaste（6）Wasteofmotion（7）Wastefromproductdefects4JITDemand-PullLogicCustomersSubSubFabFabFabFabVendorVendorVendorVendorFinalAssembly5MinimizingWaste:

FocusedFactoryNetworksFinalAssemblyCoordinationSystemIntegration6TraditionalConveyanceABCACBSporadicandInfrequentDeliveriesfromIndividualSuppliers7Mixed-LoadDeliveryABCABCRegularandFrequentDeliveriesfromManySuppliers8MinimizingWaste:

GroupTechnologyUsingDepartmentalSpecializationforplantlayoutcancausealotofunnecessarymaterialmovement.SawSawLathePressPressGrinderLatheLatheSawPressHeatTreatGrinder9MinimizingWaste:

GroupTechnologyRevisingbyusingGroupTechnologyCellscanreducemovementandimproveproductflow.PressLatheGrinderGrinderA2BSawHeatTreatLatheSawLathePressLathe110MinimizingWaste:

UniformPlantLoadingNotuniformJan.UnitsFeb.UnitsMar.UnitsTotal1,2003,5004,3009,000UniformJan.UnitsFeb.UnitsMar.UnitsTotal3,0003,0003,0009,000Supposeweoperateaproductionplantthatproducesasingleproduct.Thescheduleofproductionforthisproductcouldbeaccomplishedusingeitherofthetwoplantloadingschedulesbelow.Howdoestheuniformloadinghelpsavelaborcosts?

or11MixedBatchExampleCompanyproducesthreeproductswithamixedmodelassemblyline.Operates16hoursperdayfor250days/yr.DeterminethemixedmodelMPSforadailybatch.DetermineminimumbatchMPSandthemixscheduleforaday.ProductsForecasts（year）120,000210,00035,00012Calculations#1#2#3YearForecast20000100005000DailyBatchdivideby250804020HourlyBatchdivideby1652.51.25MinimumBatchMPS421Foreveryunitof#3（minimumbatch）,weneedtwiceasmany#2and4timesAsmany#1soforminimumbatch:

Produceduringeachdayproduce#1,1,1,1,2,2,3-repeated20times13MixedBatchExampleCompanyproducesfourproductswithamixedmodelassemblyline.Operates8hoursperdayfor250days/yr.DeterminethemixedmodelMPSforadailyandhourlybatch.Determinemixscheduleforaday.ProductsForecasts（year）I500II1500III4500IV600014MinimizingWaste:

Just-In-TimeProductionManagementphilosophy“Pull”systemthoughtheplantWHATITISEmployeeparticipationIndustrialengineering/basicsContinuingimprovementTotalqualitycontrolSmalllotsizesWHATITREQUIRESAttackswasteExposesproblemsandbottlenecksAchievesstreamlinedproductionWHATITDOESStableenvironmentWHATITASSUMES15MinimizingWaste:

InventoryHidesProblemsWorkinprocessqueues（banks）ChangeordersEngineeringdesignredundanciesVendordelinquenciesScrapDesignbacklogsMachinedowntimeDecisionbacklogsInspectionbacklogsPaperworkbacklogExample:

Byidentifyingdefectiveitemsfromavendorearlyintheproductionprocessthedownstreamworkissaved.Example:

Byidentifyingdefectiveworkbyemployeesupstream,thedownstreamworkissaved.16MinimizingWaste:

KanbanProductionControlSystemsStoragePartAStoragePartAMachineCenterAssemblyLineMaterialFlowCard（signal）FlowWithdrawalkanbanProductionkanban17DeterminingtheNumberofKanbansNeededSettingupakanbansystemrequiresdeterminingthenumberofkanbans（orcontainers）needed.Eachcontainerrepresentstheminimumproductionlotsize.Anaccurateestimateoftheleadtimerequiredtoproduceacontaineriskeytodetermininghowmanykanbansarerequired.18TheNumberofKanbanCardSetsk=Numberofkanbancardsets（asetisacard）d=AveragenumberofunitsdemandedoversometimeperiodL=leadtimetoreplenishanorder（sameunitsoftimeasdemand）S=SafetystockexpressedasapercentageofdemandduringleadtimeC=Containersize19CSdLk）（1containertheofSizestockSafetytimeleadduringdemandExpectedExampleofKanbanCardDetermination:

ProblemDataAswitchassemblyisassembledinbatchesof4unitsfroman“upstream”assemblyareaanddeliveredinaspecialcontainertoa“downstream”control-panelassemblyoperation.Thecontrol-panelassemblyarearequires5switchassembliesperhour.Theswitchassemblyareacanproduceacontainerofswitchassembliesin2hours.Safetystockhasbeensetat10%ofneededinventory.20ExampleofKanbanCardDetermination:

CalculationsAlwaysroundup!

213or,75.245

（2）（1.1）（1containertheofSizestockSafetytimeleadduringdemandExpectedCSdLkJITRequirements:

DesignFlowProcessLinkoperationsBalanceworkstationcapacitiesRe-layoutforflowEmphasizepreventivemaintenanceReducelotsizesReducesetup/changeovertime22JITRequirements:

ImproveProductDesignStandardproductconfigurationStandardizeandreducenumberofpartsProcessdesignwithproductdesignQualityexpectations23RespectforPeopleLevelpayrollsCooperativeemployeeunionsSubcontractornetworksInvertedpyramidmanagementstyleSmallgroupinvolvementactivities24JITRequirements:

TotalQualityControlWorkerresponsibilityMeasureSQCEnforcecomplianceFail-safe（Poke-yoke）methodsAutomaticinspection25POKE-YOKEsaddressMistakesDamagedpartsMissingpartsReversedpartsWrongpartsWrongsizeorshapeWrongchemicalpropertiesWrongphysicalpropertiesWrongitemshippedWronglabelWrongpackageDamagedfinishedproductOmittingapartOmittingaprocessPerformingaprocessincorrectlyPerformingaprocessonthewrongpartPerformingaprocessinimproperenvironmentalconditionsPerformingthewrongprocessSettingupequipmentincorrectlySettingupaworkpieceincorrectlyAdjustingequipmentincorrectlyToolingsetupincorrectlyToolingadjustedincorrectlyInstallingwrongpartInstallingpartincorrectlyDEFECTSMISTAKES26JITRequirements:

WorkwithVendorsReduceleadtimesFrequentdeliveriesProjectusagerequirementsQualityexpectations27JITRequirements:

ReduceInventoryMoreLookforotherareaswhereinventoryhidesStoresTransitCarouselsConveyors28MRPandJITMRPisaplanningsystemthatdoesnotdodetailedshopfloorschedulingMRPrequiresfixedleadtimeswhichmightactuallyvarywithbatchsizeJITexcelsatrapidlymovingsmallbatchesofmaterialthroughthesystem29MRPSmallBucketApproach1.MRP“buckets”arereducedtodailyorhourlyThemostcommonplanningperiod（timebucket）forMRPsystemsisweekly2.Plannedreceiptsareusedinternallytosequenceproduction3.InventoryismovedthroughtheplantonaJITbasis4.CompletedproductsaremovedtofinishedgoodsinventorywhichreducesrequiredquantitiesforsubsequentplannedordersBackflushingbasedontheBOMisusedtodeductinventorythatwasusedinproduction30MRPBalancedFlowUsedinrepetitiveoperationsMRPplansareexecutedusingJITtechniquesbasedon“pull”principlesFlowsarecarefullybalancedwithsmalllotsizes31MRPvs.TheSupermarketItemsusedbymanyproductsareheldinacommonareaoftencalledasupermarketItemsarewithdrawnasneededInventoryismaintainedusingJITsystemsandproceduresCommonitemsarenotplannedbytheMRPsystem32