Just in Time and Lean Production

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Chapter 11Chapter 11

Just-In-Time and Just-In-Time and Lean ProductionLean Production

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JIT: Definitions? JIT: Definitions?

• JIT Head

• Chicken JIT

• Oh JIT (O´JIT)

• Tough JIT

• Strate JITs

• JIT Planes • Bull JIT • Le JIT • JIT Lag • When the JIT hits

the fan.

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Producing only what is needed, Producing only what is needed, when it is neededwhen it is needed

A philosophy A philosophy An integrated management systemAn integrated management systemJIT’s mandate: JIT’s mandate:

Eliminate all wasteEliminate all waste

What is JIT ?What is JIT ?

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What is JIT?What is JIT?• a corporate system designed to produce

output within the minimum lead time and at the lowest total cost by continuously identifying and eliminating all forms of corporate waste and variance.

• a corporate strategy • a philosophy • Focus of JIT:

• variance & waste

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Seven Basic Types of Seven Basic Types of WasteWaste

• Waste from overproduction

• Waste from waiting times

• Transportation waste

• Process Waste

• Inventory Waste

• Waste of motion

• Waste from product defects

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Figure 11.1Figure 11.1

Waste in OperationsWaste in Operations

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Figure 11.1Figure 11.1

Waste in OperationsWaste in Operations

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Figure 11.1Figure 11.1

Waste in OperationsWaste in Operations

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Common Causes of Common Causes of Waste Waste

• Layout (distance)

• Long setup time

• Incapable processes

• Poor maintenance

• Poor work methods

• Lack of training

• Inconsistent performance measures

• Ineffective production planning

• Lack of workplace organization

• Poor supply quality/reliability

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Objectives of JIT Objectives of JIT • Produce only the products the customer wants. • Produce products only at the rate that the customer

wants them. • Produce with perfect quality• Produce with minimum lead time.• Produce products with only those features the

customer wants. • Produce with no waste of labor, material or equipment

-- every movement must have a purpose so that there is zero idle inventory.

• Produce with methods that allow for the development of people

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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. Small-lot productionSmall-lot 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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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 parts

Work flows in one direction Work flows in one direction through cellthrough cell

Cycle 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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JIT Principles JIT Principles • Create flow production • one piece flow

• machines in order of processes • small and inexpensive equipment • U cell layout, counter clockwise • multi-process handling workers • easy moving/standing operations • standard operations defined

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Balanced Production Balanced Production

• TAKT time

• Objective -- Build at rate that the customer wants work

• Balance the system to maximize efficiency at this rate

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TAKT Time TAKT Time

• TAKT

• the beat

• (Net Available Operating Time) / Customer Requirements

• time periods must be consistent

• Example of calculation

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TAKT Time Example TAKT Time Example • Net Available Operating Time • Time per shift 480´ • Breaks (2 @ 10´) - 20´ • Clean-up - 20 • Lunch - 30

• NAOT/shift 410´• Customer Requirements • Monthly 26,000 • No. Working Days 20

• CR/Day 1,300• T/T • 410´/shift*60"/min*3 shifts/1,300

• 56.769" per part or 57"

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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 schedule

Forces 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 production

Derived from two-bin inventory systemDerived from two-bin inventory system Kanban maintains discipline of pull Kanban maintains discipline of pull

productionproduction Production kanban authorizes productionProduction kanban authorizes production Withdrawal 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) Two-bin inventory systema) Two-bin 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 quantity

RR = reorder point - demand during lead time = reorder point - demand 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 Kanbans Kanban SquareKanban Square

Marked area designed to hold itemsMarked area designed to hold items Signal 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 Kanbans

Rotate between the factory and suppliersRotate between the factory and suppliers

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Determining Number of Determining Number of KanbansKanbans

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

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

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Determining the Number Determining the Number of Kanbansof Kanbansdd = 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

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)

NN = == =

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

dLdL + + SSCC

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

252575 + 7.575 + 7.5

2525

Example 11.1Example 11.1

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Small-Lot ProductionSmall-Lot Production

Requires less space & capital Requires less space & capital investmentinvestment

Moves 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 time Reduce distances, simplify Reduce distances, simplify

movements, standardizemovements, standardize routingsroutingsWaiting timeWaiting time

Better scheduling, sufficient capacityBetter scheduling, sufficient capacitySetup timeSetup time

Generally the biggest bottleneckGenerally the biggest bottleneck

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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 toSpot 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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Benefits of JITBenefits of JIT1.1. Reduced Reduced

inventoryinventory2.2. 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 flexibilityGreater flexibility

8.8. Better relations Better relations with supplierswith suppliers

9.9. 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

varietyvariety

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Use JIT to finely tune an Use JIT to finely tune an operating systemoperating system

Somewhat different in Somewhat different in USA than JapanUSA than Japan

JIT is still evolvingJIT is still evolvingJIT isn’t for everyoneJIT isn’t for everyone

JIT ImplementationJIT Implementation