操作管理OperationManagementHeizer9ch課件

1、Operations ManagementChapter 16 JIT and Lean OperationsPowerPoint presentation to accompany Heizer/Render Principles of Operations Management, 7eOperations Management, 9e OutlineGlobal Company Profile: Toyota Motor CorporationJust-in-Time, the Toyota Production System, and Lean OperationsEliminate W

2、asteRemove VariabilityImprove ThroughputOutline ContinuedJust-in-TimeJIT PartnershipsConcerns of SuppliersJIT LayoutDistance ReductionIncreased FlexibilityImpact on EmployeesReduced Space and InventoryOutline ContinuedJIT InventoryReduce VariabilityReduce InventoryReduce Lot SizesReduce Setup CostsJ

3、IT SchedulingLevel SchedulesKanbanOutline ContinuedJIT QualityToyota Production SystemContinuous ImprovementRespect for PeopleStandard Work PracticesLean OperationsBuilding a Lean OrganizationLean Operations in ServicesLearning ObjectivesWhen you complete this chapter you should be able to:Define ju

4、st-in-time, TPS, and lean operationsDefine the seven wastes and the 5 SsExplain JIT partnershipsDetermine optimal setup timeLearning ObjectivesWhen you complete this chapter you should be able to:Define kanbanCompute the required number of kanbansExplain the principles of the Toyota Production Syste

5、mToyota Motor CorporationLargest vehicle manufacturer in the world with annual sales of over 9 million vehiclesSuccess due to two techniques, JIT and TPSContinual problem solving is central to JITEliminating excess inventory makes problems immediately evidentToyota Motor CorporationCentral to TPS is

6、 a continuing effort to produce products under ideal conditionsRespect for people is fundamentalSmall building but high levels of productionSubassemblies are transferred to the assembly line on a JIT basisHigh quality and low assembly time per vehicleJust-In-Time, TPS, and Lean OperationsJIT is a ph

7、ilosophy of continuous and forced problem solving via a focus on throughput and reduced inventoryTPS emphasizes continuous improvement, respect for people, and standard work practicesLean production supplies the customer with their exact wants when the customer wants it without wasteJust-In-Time, TP

8、S, and Lean OperationsJIT emphasizes forced problem solvingTPS emphasizes employee learning and empowerment in an assembly-line environmentLean operations emphasize understanding the customerEliminate WasteWaste is anything that does not add value from the customer point of viewStorage, inspection,

9、delay, waiting in queues, and defective products do not add value and are 100% wasteOhnos Seven WastesOverproductionQueuesTransportationInventoryMotionOverprocessingDefective productsEliminate WasteOther resources such as energy, water, and air are often wastedEfficient, ethical, and socially respon

10、sible production minimizes inputs, reduces wasteTraditional “housekeeping” has been expanded to the 5 SsThe 5 SsSort/segregate when in doubt, throw it outSimplify/straighten methods analysis toolsShine/sweep clean dailyStandardize remove variations from processesSustain/self-discipline review work a

11、nd recognize progressThe 5 SsSort/segregate when in doubt, throw it outSimplify/straighten methods analysis toolsShine/sweep clean dailyStandardize remove variations from processesSustain/self-discipline review work and recognize progressTwo additional SsSafety build in good practicesSupport/mainten

12、ance reduce variability and unplanned downtimeRemove VariabilityJIT systems require managers to reduce variability caused by both internal and external factorsVariability is any deviation from the optimum processInventory hides variabilityLess variability results in less wasteSources of VariabilityI

13、ncomplete or inaccurate drawings or specificationsPoor production processes resulting in incorrect quantities, late, or non-conforming unitsUnknown customer demandsSources of VariabilityIncomplete or inaccurate drawings or specificationsPoor production processes resulting in incorrect quantities, la

14、te, or non-conforming unitsUnknown customer demandsBoth JIT and inventory reduction are effective tools in identifying causes of variabilityImprove ThroughputThe time it takes to move an order from receipt to deliveryThe time between the arrival of raw materials and the shipping of the finished orde

15、r is called manufacturing cycle timeA pull system increases throughputImprove ThroughputBy pulling material in small lots, inventory cushions are removed, exposing problems and emphasizing continual improvementManufacturing cycle time is reducedPush systems dump orders on the downstream stations reg

16、ardless of the needJust-In-Time (JIT)Powerful strategy for improving operationsMaterials arrive where they are needed when they are neededIdentifying problems and driving out waste reduces costs and variability and improves throughputRequires a meaningful buyer-supplier relationshipJIT and Competiti

17、ve AdvantageFigure 16.1JIT and Competitive AdvantageFigure 16.1JIT PartnershipsJIT partnerships exist when a supplier and purchaser work together to remove waste and drive down costsFour goals of JIT partnerships are:Removal of unnecessary activitiesRemoval of in-plant inventoryRemoval of in-transit

18、 inventoryImproved quality and reliabilityJIT PartnershipsFigure 16.2Concerns of SuppliersDiversification ties to only one customer increases riskScheduling dont believe customers can create a smooth scheduleChanges short lead times mean engineering or specification changes can create problemsQualit

19、y limited by capital budgets, processes, or technologyLot sizes small lot sizes may transfer costs to suppliersJIT LayoutTable 16.1Reduce waste due to movementJIT Layout TacticsBuild work cells for families of productsInclude a large number operations in a small areaMinimize distanceDesign little sp

20、ace for inventoryImprove employee communicationUse poka-yoke devicesBuild flexible or movable equipmentCross-train workers to add flexibilityDistance ReductionLarge lots and long production lines with single-purpose machinery are being replaced by smaller flexible cellsOften U-shaped for shorter pat

21、hs and improved communicationOften using group technology concepts Increased FlexibilityCells designed to be rearranged as volume or designs changeApplicable in office environments as well as production settingsFacilitates both product and process improvementImpact on EmployeesEmployees are cross tr

22、ained for flexibility and efficiencyImproved communications facilitate the passing on of important information about the processWith little or no inventory buffer, getting it right the first time is criticalReduced Space and InventoryWith reduced space, inventory must be in very small lotsUnits are

23、always moving because there is no storageInventoryInventory is at the minimum level necessary to keep operations runningJIT Inventory TacticsUse a pull system to move inventoryReduce lot sizesDevelop just-in-time delivery systems with suppliersDeliver directly to point of usePerform to scheduleReduc

24、e setup timeUse group technologyTable 16.2Reduce VariabilityInventory levelProcess downtimeScrapSetup timeLate deliveriesQuality problemsFigure 16.3Inventory levelReduce VariabilityScrapSetup timeLate deliveriesQuality problemsProcess downtimeFigure 16.3Reduce Lot SizesFigure 16.4200 100 InventoryTi

25、meQ2When average order size = 100average inventory is 50Q1When average order size = 200average inventory is 100Reduce Lot SizesIdeal situation is to have lot sizes of one pulled from one process to the nextOften not feasibleCan use EOQ analysis to calculate desired setup timeTwo key changes necessar

26、yImprove material handlingReduce setup timeLot Size ExampleD=Annual demand = 400,000 unitsd=Daily demand = 400,000/250 = 1,600 per dayp=Daily production rate = 4,000 unitsQ=EOQ desired = 400H=Holding cost = $20 per unitS=Setup cost (to be determined)Q =2DSH(1 - d/p)Q2 =2DSH(1 - d/p)S = = = $2.40(Q2)

27、(H)(1 - d/p)2D(3,200,000)(0.6)800,000Setup time = $2.40/($30/hour) = 0.08 hr = 4.8 minutesReduce Setup CostsHigh setup costs encourage large lot sizesReducing setup costs reduces lot size and reduces average inventorySetup time can be reduced through preparation prior to shutdown and changeoverLower

28、 Setup CostsFigure 16.5Sum of ordering and holding costsHolding costSetup cost curves (S1, S2)T1S1T2S2CostLot sizeReduce Setup TimesFigure 16.6Use one-touch system to eliminate adjustments (save 10 minutes)Step 4Step 5Training operators and standardizing work procedures (save 2 minutes)Initial Setup

29、 TimeStep 2Move material closer and improve material handling (save 20 minutes)Step 1Separate setup into preparation and actual setup, doing as much as possible while the machine/process is operating (save 30 minutes)Step 3Standardize and improve tooling (save 15 minutes)90 min 60 min 45 min 25 min

30、15 min 13 min Repeat cycle until subminute setup is achievedStep 6JIT SchedulingSchedules must be communicated inside and outside the organizationLevel schedulesProcess frequent small batchesFreezing the schedule helps stabilityKanbanSignals used in a pull systemTable 16.3Better scheduling improves

31、performanceJIT Scheduling TacticsCommunicate schedules to suppliersMake level schedulesFreeze part of the schedulePerform to scheduleSeek one-piece-make and one-piece moveEliminate wasteProduce in small lotsUse kanbansMake each operation produce a perfect partJIT SchedulingLevel SchedulesProcess fre

32、quent small batches rather than a few large batchesMake and move small lots so the level schedule is economical“Jelly bean” schedulingFreezing the schedule closest to the due dates can improve performanceScheduling Small LotsABCAAABBBBBCJIT Level Material-Use ApproachACAAABBBBBCCBBBBAALarge-Lot Appr

33、oachTimeFigure 16.7KanbanKanban is the Japanese word for cardThe card is an authorization for the next container of material to be producedA sequence of kanbans pulls material through the processMany different sorts of signals are used, but the system is still called a kanbanKanbanUser removes a sta

34、ndard sized containerSignal is seen by the producing department as authorization to replenishPart numbers mark locationSignal marker on boxesFigure 16.8KanbanFigure 16.9Work cellRaw Material SupplierKanbanPurchased Parts SupplierSub-assemblyShipKanbanKanbanKanbanKanbanFinished goodsCustomer orderFin

35、al assemblyKanbanMore KanbanWhen the producer and user are not in visual contact, a card can be usedWhen the producer and user are in visual contact, a light or flag or empty spot on the floor may be adequateSince several components may be required, several different kanban techniques may be employe

36、dMore KanbanUsually each card controls a specific quantity or partsMultiple card systems may be used if there are several components or different lot sizesIn an MRP system, the schedule can be thought of as a build authorization and the kanban a type of pull system that initiates actual productionMo

37、re KanbanKanban cards provide a direct control and limit on the amount of work-in-process between cellsIf there is an immediate storage area, a two-card system can be used with one card circulating between the user and storage area and the other between the storage area and the producerThe Number of

38、 Kanban Cardsor ContainersNeed to know the lead time needed to produce a container of partsNeed to know the amount of safety stock neededNumber of kanbans(containers)Demand during Safetylead time+stockSize of container=Number of Kanbans ExampleDaily demand=500 cakesProduction lead time=2 days(Wait t

39、ime + Material handling time + Processing time)Safety stock=1/2 dayContainer size=250 cakesDemand during lead time = 2 days x 500 cakes = 1,000Number of kanbans = = 51,000 + 250250Advantages of KanbanAllow only limited amount of faulty or delayed materialProblems are immediately evidentPuts downward

40、 pressure on bad aspects of inventoryStandardized containers reduce weight, disposal costs, wasted space, and laborQualityStrong relationshipJIT cuts the cost of obtaining good quality because JIT exposes poor qualityBecause lead times are shorter, quality problems are exposed soonerBetter quality means fewer buffers and allows simpler JIT systems to be usedJIT Quality TacticsUse statistical process controlEmpower employeesBuild fail-safe methods (poka-yoke, checklists, etc.)Expose poor quality with small lot JITProvide i