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JIT – Just-In-Time Production

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Introduction to JIT

Overview of JIT JIT is a pull production system

Catch Phrase “The right part in the right place at the right

time”

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History of JIT

Taiichi Ohno of the Toyota Motor Corporation is often referred to as “The Father of JIT.” The JIT management philosophy has been around since the 1950’s, which is when Ohno first started developing and practicing JIT concepts within the Toyota Corporation. Ohno titled his new methods of production the Toyota Production System (TPS), which has now become a synonymous term for JIT

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Toyota’s Lean Production House

Goal: highest quality, lowest cost, shortest leadtime

Heijunka 5S Standardized Work Kaizen

JidokaJust in Time (JIT) – continuous flow, pull system, or kanban

JIT

Stability – Stable Manufacturing Processes, 100% Quality, Total Preventative Maintenance

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Synonyms for JIT

Toyota Production System

Stockless production

Lean production

Kanban system

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JIT Goal and Philosophies

GOAL of JIT:Production control through waste elimination

Philosophy of JIT Elimination of waste Broad view of operations Simplicity Continuous improvement Visibility Flexibility

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JIT Principles

SimplificationCleanliness and organizationVisibilityCycle timingAgilityVariation reductionMeasurement

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Elements of JIT

Meet daily

Discuss work practices

Reduce buffer stock

Modify machinery – reduced setup

Reveal non-value added practices

Involve the workforce: consultation instead of confrontation

Expose problems

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Benefits of JIT

Better quality products

Reduced scrap and rework

Reduced cycle times

Lower setup times

Smoother production flow

Cost savings

Less inventory

Higher productivity

Most skilled workforce

Reduced space requirements

Higher work participation

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Toyota’s Seven Wastes

Producing defects

Transportation

Inventory

Overproduction

Waiting Time

Processing

Motion

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Canon’s Nine Wastes

Work-in-processDefectsEquipmentExpenseIndirect laborPlanningHuman resourcesOperationsStartup

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The Five Why’s

Ask “Why” five times to get to the source of waste and the cause of problems

1. Why did the machine stop? Overload and blown fuse

2. Why the overload? Not lubricated

3. Why not lubricated? Oil pump not pumping

4. Why not pumping? Pump shaft worn out

5. Why worn out? No screen, scrap was let in

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Push vs. Pull

Push System Material is pushed downstream and inventory

builds regardless of resource availability Strong emphasis on production first Stock points and additional inventory can

overflow with parts and raw materials

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Traditional Push Production System

• Huge lot sizes• Lots of inventory• “Push” material to next stage

Big purchaseshipments w/

lower perunit shipping

cost

Big “pushes”of finished

goods towarehouse or

customers

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Pull vs. Push

Pull System The customer starts the production process by

pulling production when it is needed Material is moved to workstations as it is

needed Stock points are kept at a minimum Waste is MINIMIZED

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Pull Production System

• Smaller lots• Faster setups• Less inventory

Smallershipments w/

minimal /no inventoryholding cost

Goods are“pulled” by

demand outof the plant

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Necessary Conditions For Pull

1. Planning and Control Responsibility

2. Producing to Meet Demand

3. Reduce In-Process Inventories

4. Preventative Maintenance

5. Quality Assurance

6. Setup Times Must be Small

7. Linking of All Operations

8. Production Plans and Schedules Must Be Uniform

9. Develop Cooperative Attitudes and Teamwork

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Achieving Pull Production

Pull System as Reorder Point (ROP) System

D = demand (consumption rate)LT = lead time (elapsed time btwn order and

replenishment

P = production timeC = conveyance time (time to convey order to

upstream process, plus time to move materials to the downstream operation

SS = safety stock (number of parts)

SSLTDROP )(

CPLT

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Achieving Pull Production

Standard-Sized Containers If Q = the capacity of a standard container, then

ROP as expressed in terms of the number of containers is K, or the maximum number of completely full containers in a buffer

Container Size Container should hold about 10% of the daily

demand

Q

CPDK

)(

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Kanban

Kanban card shows typical production quantity

Derived from two-bin inventory system

Maintains pull production system

A production kanban authorized production

A withdrawal kanban authorizes material handling

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Kanban Pre-Conditions

There are four pre-conditions for

the successful implementation of

Kanban

Point of use Point of use inclusion (all parts inclusion (all parts on the assembly line)on the assembly line)

Level productionLevel production

Stabilized processesStabilized processesQuick Changeover Quick Changeover proceduresprocedures

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Kanban

Kanban means “signboard” Kanban is a signal used to communicate

production cues in a pull production system

A

B

Storage

Machine Center Assembly Line

ProductionKanban

WithdrawalKanban

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Sample Kanban Card

Part No.: 6934Description: Servo motor

Box capacity: 30Box type: AFIssue No.: 06

To:

StationD-7

Assembly3

From:

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Sample Kanban Card

Market Address

<<Market_Address>>

Kanban Number

<<Kanban_Number>>

Line-Side Address

<<Line_Side_Address>>

Part Number

<<Part Number>>

Route

<<Route>>

Part Description

<<Part Number>>

Bar Code Area

Dock Code

<<Dock Code>>Supplier Code

<<Supplier Code >>

Quantity

<<Quantity>>

Serial Number

Comment:<<Comment>>

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Conveyance Kanbans

A conveyance kanban, or C-kanban, authorizes containers to move from an upstream, outbound buffer to a downstream, inbound bufferKc = number of C-kanbans

C = total time between when workers remove a C-kanban from a full container at the inbound buffer and when they remove a C-kanban from the next full container

Q

CDKc

)(

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Production Kanbans

P-kanban is used to authorize production parts to assembliesKp = number of P-kanbans

P = total time elapsed from when workers or mat’l handlers remove the P-kanban from a full container and post it at the outbound buffer until the time they remove the P-kanban from the next full container

Q

PDKp

)(

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1 & 2-Card Kanban Systems

1-card systems use only C-kanbans

2-card systems use both C-kanbans and P-kanbans

DISCUSSION

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