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Chapter 11Chapter 11

JustJust--InIn--Time and Time and Lean ProductionLean Production

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What is JIT ?What is JIT ?Producing only what is needed, Producing only what is needed, when it is neededwhen it is neededA philosophy A philosophy An integrated management systemAn integrated management systemJIT’s mandate: JIT’s mandate: Eliminate all wasteEliminate all waste

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Basic Elements of JITBasic Elements of JIT1.1. Flexible resourcesFlexible resources2.2. Cellular layoutsCellular layouts3.3. Pull production systemPull production system4.4. Kanban production controlKanban production control5.5. SmallSmall--lot productionlot production6.6. Quick setupsQuick setups7.7. Uniform production levelsUniform production levels8.8. Quality at the sourceQuality at the source9.9. Total productive maintenanceTotal productive maintenance10.10. Supplier networksSupplier networks

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Waste in OperationsWaste in Operations

Figure 11.1Figure 11.1

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Waste in OperationsWaste in Operations

Figure 11.1Figure 11.1

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Waste in OperationsWaste in Operations

Figure 11.1Figure 11.1

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Flexible ResourcesFlexible Resources

Multifunctional workersMultifunctional workersGeneral purpose machinesGeneral purpose machinesStudy operators & improve Study operators & improve operationsoperations

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Standard Operating Routine Standard Operating Routine for a Workerfor a Worker

Standard Operating RoutineSheet 1

Worker: RussellCycle Time: 2 min

Order of Operations timeOperations :10 :20 :30 :40 :50 1:00 1:10 1:20 1:30 1:40 1:50 2:00

Pick up material

Unload/load machine 1

Unload/load machine 2

Unload/load machine 3

Inspect/pack

Figure 11.2Figure 11.2

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Cellular LayoutsCellular LayoutsGroup dissimilar machines in Group dissimilar machines in manufacturing cell to produce manufacturing cell to produce family of partsfamily of partsWork flows in one direction Work flows in one direction through cellthrough cellCycle time adjusted by changing Cycle time adjusted by changing worker pathsworker paths

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Manufacturing Cell with Manufacturing Cell with Worker RoutesWorker Routes

Worker Worker 11

Worker Worker 22

Worker Worker 33

Cell 1Cell 1

Figure 11.3Figure 11.3

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Worker Routes Lengthened Worker Routes Lengthened as Volume Decreasesas Volume Decreases

Cell 5Cell 5

Worker Worker 22

Cell 2Cell 2

Worker Worker 11

Cell 1Cell 1

Worker Worker 33

Cell 3Cell 3 Cell 4Cell 4

Figure 11.4Figure 11.4

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The Pull SystemThe Pull SystemMaterial is pulled through the system Material is pulled through the system when neededwhen neededReversal of traditional push system Reversal of traditional push system where material is pushed according where material is pushed according to a scheduleto a scheduleForces cooperationForces cooperationPrevent over and underproductionPrevent over and underproduction

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Kanban Production Kanban Production Control SystemControl System

Kanban card indicates standard quantity Kanban card indicates standard quantity of productionof productionDerived from twoDerived from two--bin inventory systembin inventory systemKanban maintains discipline of pull Kanban maintains discipline of pull productionproductionProduction kanban authorizes productionProduction kanban authorizes productionWithdrawal kanban authorizes movement Withdrawal kanban authorizes movement of goodsof goods

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A Sample KanbanA Sample Kanban

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The Origin of KanbanThe Origin of Kanbana) Twoa) Two--bin inventory systembin inventory system b) Kanban inventory systemb) Kanban inventory system

Reorder Reorder cardcard

Bin 1Bin 1

Bin 2Bin 2

Q - R

KanbanKanban

RR

QQ = order quantity= order quantityRR = reorder point = reorder point -- demand during lead timedemand during lead time

Figure 11.5Figure 11.5

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Types of KanbansTypes of Kanbans

Figure 11.6Figure 11.6

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Types of KanbansTypes of Kanbans

Figure 11.6Figure 11.6

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Types of KanbansTypes of Kanbans

Figure 11.6Figure 11.6

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Types of KanbansTypes of KanbansKanban SquareKanban Square

Marked area designed to hold itemsMarked area designed to hold itemsSignal KanbanSignal Kanban

Triangular kanban used to signal Triangular kanban used to signal production at the previous workstationproduction at the previous workstation

Material KanbanMaterial KanbanUsed to order material in advance of a Used to order material in advance of a processprocess

Supplier KanbansSupplier KanbansRotate between the factory and suppliersRotate between the factory and suppliers

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Determining Number of Determining Number of KanbansKanbans

No. of Kanbans =No. of Kanbans =average demand during lead time + safety stockaverage demand during lead time + safety stock

container sizecontainer size

NN == dLdL + + SS

CC

wherewhere

NN = number of kanbans or containers= number of kanbans or containersdd = average demand over some time period= average demand over some time periodLL = lead time to replenish an order= lead time to replenish an orderSS = safety stock= safety stockCC = container size= container size

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Determining the Number Determining the Number of Kanbansof Kanbans

dd = 150 bottles per hour= 150 bottles per hourLL = 30 minutes = 0.5 hours= 30 minutes = 0.5 hoursSS = 0.10(150 x 0.5) = 7.5= 0.10(150 x 0.5) = 7.5CC = 25 bottles= 25 bottles

NN = == =

= = 3.3 kanbans or containers= = 3.3 kanbans or containers

dLdL + + SSCC

(150 x 0.5) + 7.5(150 x 0.5) + 7.52525

75 + 7.575 + 7.52525

Round up to 4 (to allow some slack) or Round up to 4 (to allow some slack) or down to 3 (to force improvement)down to 3 (to force improvement)

Example 11.1Example 11.1

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SmallSmall--Lot ProductionLot ProductionRequires less space & capital Requires less space & capital investmentinvestmentMoves processes closer togetherMoves processes closer togetherMakes quality problems easier to Makes quality problems easier to detectdetectMakes processes more dependent Makes processes more dependent on each otheron each other

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Inventory Hides ProblemsInventory Hides Problems

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Lower Levels of Inventory Lower Levels of Inventory Expose ProblemsExpose Problems

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Components of Lead TimeComponents of Lead TimeProcessing timeProcessing time

Reduce number of items or improve Reduce number of items or improve efficiencyefficiency

Move timeMove timeReduce distances, simplify Reduce distances, simplify movements, standardizemovements, standardize routingsroutings

Waiting timeWaiting timeBetter scheduling, sufficient capacityBetter scheduling, sufficient capacity

Setup timeSetup timeGenerally the biggest bottleneckGenerally the biggest bottleneck

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SMED PrinciplesSMED Principles1.1. Separate internal setup from Separate internal setup from

external setupexternal setup2.2. Convert internal setup to external Convert internal setup to external

setupsetup3.3. Streamline all aspects of setupStreamline all aspects of setup4.4. Perform setup activities in Perform setup activities in

parallel or eliminate them entirelyparallel or eliminate them entirely

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Uniform ProductionUniform ProductionResults from smoothing production Results from smoothing production requirementsrequirementsKanban systems can handle +/Kanban systems can handle +/-- 10% 10% demand changesdemand changesSmooths demand across planning Smooths demand across planning horizonhorizonMixedMixed--model assembly steadies model assembly steadies component productioncomponent production

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MixedMixed--Model SequencingModel Sequencing

Example 11.2Example 11.2

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Quality at the SourceQuality at the SourceJidoka is authority to stop production Jidoka is authority to stop production linelineAndon lights signal quality problemsAndon lights signal quality problemsUndercapacity scheduling allows for Undercapacity scheduling allows for planning, problem solving & planning, problem solving & maintenancemaintenanceVisual control makes problems visibleVisual control makes problems visiblePokaPoka--yoke prevents defectsyoke prevents defects

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KaizenKaizenContinuous improvementContinuous improvementRequires total employment Requires total employment involvementinvolvementEssence of JIT is willingness of Essence of JIT is willingness of workers toworkers to

Spot quality problemsSpot quality problemsHalt production when necessaryHalt production when necessaryGenerate ideas for improvementGenerate ideas for improvementAnalyze problemsAnalyze problemsPerform different functionsPerform different functions

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Total Productive Total Productive Maintenance (TPM)Maintenance (TPM)

Breakdown maintenanceBreakdown maintenanceRepairs to make failed machine operationalRepairs to make failed machine operational

Preventive maintenancePreventive maintenanceSystem of periodic inspection & maintenance System of periodic inspection & maintenance to keep machines operatingto keep machines operating

TPM combines preventive maintenance & TPM combines preventive maintenance & total quality conceptstotal quality concepts

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TPM Requires TPM Requires Management to:Management to:

Design products that can be easily Design products that can be easily produced on existing machinesproduced on existing machinesDesign machines for easier operation, Design machines for easier operation, changeover, maintenancechangeover, maintenanceTrain & retrain workers to operate machinesTrain & retrain workers to operate machinesPurchase machines that maximize Purchase machines that maximize productive potentialproductive potentialDesign preventive maintenance plan Design preventive maintenance plan spanning life of machinespanning life of machine

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Supplier PoliciesSupplier Policies1. Locate near to the customer2. Use small, side loaded trucks and ship

mixed loads3. Consider establishing small warehouses

near to the customer or consolidating warehouses with other suppliers

4. Use standardized containers and make deliveries according to a precise delivery schedule

5. Become a certified supplier and accept payment at regular intervals rather than upon delivery

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Benefits of JITBenefits of JIT8.8. Better relations Better relations

with supplierswith suppliers9.9. Simplified Simplified

scheduling and scheduling and control activitiescontrol activities

10.10. Increased capacityIncreased capacity11.11. Better use of Better use of

human resourceshuman resources12.12. More product More product

variety

1.1. Reduced Reduced inventoryinventory

2.2. Improved qualityImproved quality3.3. Lower costsLower costs4.4. Reduced space Reduced space

requirementsrequirements5.5. Shorter lead timeShorter lead time6.6. Increased Increased

productivityproductivity7.7. Greater flexibility varietyGreater flexibility

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JIT ImplementationJIT Implementation

Use JIT to finely tune an operating Use JIT to finely tune an operating systemsystemSomewhat different in Somewhat different in USA than JapanUSA than JapanJIT is still evolvingJIT is still evolvingJIT isn’t for everyoneJIT isn’t for everyone

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JIT In ServicesJIT In ServicesCompetition on speed & qualityCompetition on speed & qualityMultifunctional department store Multifunctional department store workersworkersWork cells at fastWork cells at fast--food restaurantsfood restaurantsJustJust--inin--time publishing for time publishing for textbookstextbooksConstruction firms receiving Construction firms receiving material just as neededmaterial just as needed

Chapter 11What is JIT ?Basic Elements of JITWaste in OperationsWaste in OperationsWaste in OperationsFlexible ResourcesStandard Operating Routine for a WorkerCellular LayoutsManufacturing Cell with Worker RoutesWorker Routes Lengthened as Volume DecreasesThe Pull SystemKanban Production Control SystemA Sample KanbanThe Origin of KanbanTypes of KanbansTypes of KanbansTypes of KanbansTypes of KanbansDetermining Number of KanbansDetermining the Number of KanbansSmall-Lot ProductionInventory Hides ProblemsLower Levels of Inventory Expose ProblemsComponents of Lead TimeSMED PrinciplesUniform ProductionMixed-Model SequencingQuality at the SourceKaizenTotal Productive Maintenance (TPM)TPM Requires Management to:Supplier PoliciesBenefits of JITJIT ImplementationJIT In Services