Chap017.ppt Just-In-Time Systems and Lean Thinking

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McGraw-Hill/Irwin The McGraw-Hill Companies, Inc. 2007, All Rights Reserved

Just-In-Time Systems and

Lean Thinking

Chapter 17


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Chapter 17 Outline

Philosophy of JIT

Elements of a JIT system

Stabilizing the Master

ScheduleThe Kanban System

Reducing Setup Time and

Lot Sizes

Layout and Equipment

Effect on Workers

Suppliers

Implementation of JITComparison of JIT and

MRP

Beyond JIT to Lean

Thinking


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Philosophy of JIT

Modern Roots of JIT (Toyota Production

System, Taiichi Ohno. d. 1990)

Elements of JIT

Root of JIT in repetitive manufacturing

JIT as a technique: to reduce inventory

JIT as a philosophy: a comprehensivemanagement system


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Elements of JIT

Small lot sizes (lot size one)Use of Kanban system

Quick changeover (set-ups)

Multifunction workers

Efficient layout (linear flow)

Close relationships with suppliers

Frequent deliveries from vendors

Elimination of Waste


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The Seven WastesOverproduction: Producing more than the demand for customers resulting in unnecessary

inventory, handling, paperwork, and warehouse space.

Waiting Time: Operators and machines waiting for parts or work to arrive from suppliers

or other operations.

Transportation: Double or triple movement of materials due to poor layouts, lack of

coordination and workplace organization.

Processing: Poor design or inadequate maintenance or processes requiring additional labor

or machine time.

Inventory: Excess inventory due to large lot sizes, obsolete items, poor forecasts or

improper production planning.

Motion: Wasted movements of people or extra walking to get materials.

Defects: Use of materials, labor and capacity for production of defects, sorting our bad

parts or warranty costs with customers.


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Inventory as Waste

If all our suppliers are guessing, you endup with inventory, which is the physical

embodiment of bad information.

Paul Bell, Dell, Inc. Europe.Dells inventories fell from 31 days of parts

in 1996 to 6 days in 2000.

Source: Economist, 1 April 2000, p. 57.


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Elements of JIT as a Philosophy

SetupTime

Reduction

Small Lot

Sizes

JITDelivery

fromSuppliers

Suppliers'

QualityLevel

KANBAN

System

Repetitive

MPS

Daily

Schedule

Discipline

"Pull"

Production

System

Product Design

Simplicity

Equipment &

FacilityLayout

Multi-functi

orker

Smallro

Proble

Solving

Employe

Trainin

Preventive

Maintenance

JIT


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A pull production system

A physical (normally visual) control system

Normally composed of cards and containers(production card andwithdrawalcard), but

can be any type of signal

Number of containers

Kanban System

C

DTn


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The Kanban System

The Kanban system uses simple cards or signals to

strictly control production

The basic idea is that no station is permitted to

produce more than is immediately required by thesucceeding station

This simple idea prevents the buildup of inventory

No computer is required!

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The Real Origin Of Kanban

Q - R

In the 1950s, Ohno visited Detroit to learn

about auto making from the U.S. manufacturers.

He was not impressed.

He visited a supermarket, which they did not

have in Japan, and observed the way they

restocked the shelves.He used that method as the basis for Kanban.

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Kanban System


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Kanban Cards


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Reducing Setup Times andLot Sizes

Reducing setup times:increases available capacity

increases flexibility

reduces inventory

Reduce setup times and run times simultaneously

to reduce lot sizes and throughput times

Single-digit Setup Times (Shigeo Shingo [d. 1990]or SMED System)

Small lots require short setups!


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Traditional Layout

Stockrooms

Supplier A Supplier B

Final

AssemblyWork Centers


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JIT Layout

FinalAssembly



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JIT Layout with Group Technology

FinalAssembly


Line 1

Line 2


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Effect of JIT on Workers

Multifunction workers

Cross-training

New pay system to reflect skills varietyTeamwork

Suggestion system


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Suppliers

Very close relationship with suppliers

Frequent deliveries demanded from suppliers

Sole-sourcingIntegrated supplier programs

Deliveries to production line

No inspectionhigh quality


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Features of Integrated Supplier Programs

Early supplier selection, preferably in the

design phase

Family of part sourcing to allow supplier to

take advantage of GT

Long-term relationships with small number of

suppliers

Paperwork reduction in receiving and

inspection to reduce costs


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Implementation of JIT

Obtain commitment from top management

Gain the cooperation of workforce

Start with final assembly line

Reduce setup times and lot sizes working backward from

the final assembly line

Balance fabrication rates with final assembly production

rates

Extend JIT to the suppliers


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Benefits Of JIT

1. Reduced inventory

2. Improved quality

3. Lower costs

4. Reduced space

requirements

5. Shorter lead times

6. Increased productivity7. Greater flexibility

8. Better relations withsuppliers

9. Simplified scheduling

and control activities10. Increased capacity

11. Better use of humanresources

12. More product variety

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Comparison of MRP and JIT

PullversusPush production systemsSituations for comparing MRP and JIT:

Pure repetitive manufacturing situation; JIT works

bestA batch process; JIT works well with cellular

manufacturing

A job shop; MRPII with some elements of JIT

MRP assumes the present system is correct and seeks tomake the best of that system.

JIT seeks to change the system to make it better.


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The Traditional Push System

In traditional manufacturing, an item is releasedfor production at a specified time, with an

associated due date generated by MRP.

The item moves through a sequence of operationsWhen one operation is finished, the item is

pushed to the next operation

Finally, the product is pushed to inventory, tomeet the demand forecast

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The Pull System

The pull system focuses on the output of thesystem rather than the input.

Finished products are pulled from the finaloperation in response to firm customer orders.

This leads to a chain reaction, with eachstation pulling material from its precedingstation.

JIT uses the Kanban system to control theflow of material with very little work-in-process inventory.

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Uses of MRP and JIT

JIT

Repetitive (mass)

SYNCRO MRPSemirepetitive

MRP

Nonrepetitive

(batch or job

shop)

JIT

SYNCRO MRP

MRP

Low High

Stability of Master ScheduleStability of Bill of Material


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Lean Thinking

Term coined by Womack, Jones and Roos in

1990.

Extends JIT beyond the factoryAlso applies to services

http://www.lean.org


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Five Elements of Lean Thinking

Specify valuefrom the customers point of view

Create a value stream map and remove waste

Flow the product or service through the systemPullthe product or service from the customer

Strive forperfection


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Summary

Philosophy of JIT

Elements of a JIT system

Stabilizing the Master

Schedule

The Kanban System

Reducing Setup Time and

Lot Sizes

Layout and Equipment

Effect on Workers

Suppliers

Implementation of JIT

Comparison of JIT and

MRP

Beyond JIT to Lean

Thinking


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End of Chapter Seventeen

Chap017.ppt Just-In-Time Systems and Lean Thinking

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