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The Toyota Production System

High Quality and Low Cost

Readings;

James Womack, Daniel T. Jones and Daniel Roos,The Machine that Changed the World, 1990, Ch 3 and 4

Kenneth N. McKay, The Evolution of Manufacturing Control-

What Has Been, What Will Be Working Paper 03 2001

Michael McCoby, Is There a Best Way to Build a Car?HBR Nov-Dec 1997

COST VS

DEFECTS

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Consumer Reports

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Gains of imports

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The Toyota Production System

Historical View

Performance measures

Elements of TPSDifficulties with Implementation

Six Eras of Manufacturing Practice

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Three Major Mfg Systems

from 1800 to 2000

1800 1900 2000

Machine tools, specialized machine tools, Taylorism, SPC, CNC, CAD/CAM

InterchangeableParts at U.S.

Armories

MassProductionat Ford

ToyotaProductionSystem

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Key Elements for New Mfg Systems

Japanese

Banks

Taiichi

Ohno

CNC,Integrationof Labor

Jobs,

Security

Post WarToyotaProductionSystem

EarningsHenry

Ford

Moving

AssemblyLine,etc

$5/day

Immigrant

Trans-

portation

Mass

Production

U.S.GovtRoswellLee/

John

Hall

MachineTools,

Division of

Labor

YankeeIngenuityMilitaryInterchange-able Parts

ResourcesLeaderEnablingTechnology

WorkForceMotivation

Need ofSociety

Element/

System

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Q. By what method did these

new systems come about?

A. Trial and Error

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History of the Development of the ToyotaProduction System ref; Taiichi Ohno

1945 1975

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The Toyota Production System

Historical View

Performance measures

Elements of TPSDifficulties with Implementation

Six Eras of Manufacturing Practice

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Japanese Japanese in American in A ll Europei n J apa n North A me rica North A me rica

Performance:

Producvitity (hours/Veh.) 16.8 21.2 25.1 36.2

Quality (assembly

defects/100 vehicles) 60 65 82.3 97

Layout:

Space (sq.ft./vehicle/yr) 5.7 9.1 7.8 7.8

Size of Repair Area (as %

of assembly space) 4.1 4.9 12.9 14.4

Inventories(days for 8

sample parts) 0.2 1.6 2.9 2

Work Force:

% of Work Force in Teams 69.3 71.3 17.3 0.6

Job Rotation (0 = none,

4 = frequent) 3 2.7 0.9 1.9

Suggestions/Employee 61.6 1.4 0.4 0.4

Number of Job Classes 11.9 8.7 67.1 14.8

Training of New Production

Workers (hours) 380.3 370 46.4 173.3

Absenteeism 5 4.8 11.7 12.1

Automation:

Welding (% of direct steps) 86.2 85 76.2 76.6

Painting(% of direct steps) 54.6 40.7 33.6 38.2

Assembly(% of direct steps) 1.7 1.1 1.2 3.1

Source: IMVP World Assembly Plant Survey, 1989, and J. D. Power Initial Quality Survery, 1989

Summary of Assembly Plant Characteristics, Volume Producers,1989

(Average for Plants in Each Region)

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Cost Vs DefectsRef. Machine that Changed the World Womack, Jones and Roos

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Cost Vs AutomationRef. Machine that Changed the World Womack, Jones and Roos

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The Toyota Production System

Historical View

Performance measures

Elements of TPSDifficulties with Implementation

Six Eras of Manufacturing Practice

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How do you get this kind of

performance?Womack, Jones and Roos

J T. Blacks 10 Steps

Demand Flow Technologys 9 Points

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Womack Jones and Roos

New Technology? No silver bullet

Automation?

Yes, but integrated with system Standardized Production?

Not in the usual dont stop the line sense

Lean Characteristics?

Integration of Tasks (opposite of deskilling) Identification and removal of defects (stop the line!)

kaizen institutionalizing change

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J T. Blacks 10 StepsRef; JT. Black Factory with a Future 1991

1. Form cells

2. Reduce setup

3. Integrate quality control

4. Integrate preventive maintenance5. Level and balance

6. Link cells KANBAN

7. Reduce WIP

8. Build vendor programs

9. Automate

10. Computerize

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Demand Flow Technologys

9 Points1. Product Synchronization

2. Mixed Model Process Maps

3. Sequence of Events

4. Demand at Capacity5. Operational Cycle Time

6. Total Product Cycle Time

7. Line Balancing

8. Kanbans9. Operational Method Sheets

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Current Value Stream Map

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Future Value Stream Map

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J T. Black 1, 2

1. Form Cells

Sequentialoperations, decouple

operator frommachine, parts infamilies, single pieceflow within cell

2. Reduce Setup

Externalize setup toreduce down-time

during changeover,increases flexibility

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TPS Cell

ToyotaC

ell,onepartisproduced

forevery

triparound

thecell

J T. Black

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Standardized Fixtures

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J T. Black 3, 4

3. Integrate qualitycontrol

Check part quality at

cell, poke-yoke, stopproduction whenparts are bad

4. Integrate preventivemaintenance

worker maintains

machine , runs slower

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J T. Black 5, 6

5. Level and balance

Produce to Takttime, reduce batch

sizes, smoothproduction flow

6. Link cells- Kanban

Create pull system Supermarket

System

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Balancing and Leveling

Balanced line: each process has the samecycle time. Match process time toassemble time, match production rate torate of demand (Takt time)

Leveled Line: each product is produced inthe needed distribution. The process must

be flexible to do this.

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J T. Black 7, 8

7.Reduce WIP

Make system reliable,build in mechanisms

to self correct

8. Build Vendorprogram

Propagate low WIP

policy to yourvendors, reducevendors, make on-time performance part

of expectation

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Some Basics Concepts of TPS

Smooth Flow and Produce to Takt Time

Produce to Order

Make system observable and correct

problems as they occur

Integrate Worker Skills

Institutionalize change

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Two Examples;

Takt Time

Pull Systems

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Takt Time:

demand time interval

DemandProduct

TimeAvailableTimeTakt =

Calculate Takt Time per month, day,year etc. Available time includes allshifts, and excludes all non-productive time (e.g. lunch, clean-upetc). Product demand includes over-production for low yields etc.

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Takt Time

Automobile Assembly Line; Available time = 7.5 hr X 3shifts = 22.5 hrs or 1350 minutes per day. Demand =

1600 cars per day.Takt Time = 51 sec

Aircraft Engine Assembly Line; 500 engines per year.2 shifts X 7 hrs => 14 hrs/day X 250 day/year = 3500hrs.

Takt time = 7 hrs.

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Engines shipped over a 3 month period

at aircraft engine factory B

0

2

4

6

8

10

12

7-Jun 15-Jun 23-Jun 30-Jun 7-Jul 15-Jul 24-Jul 31-Jul 7- Aug 15-Aug 24-Aug 31-Aug

Weeks

en

sp

p

we

month 1 month 2 month 3

Factory B

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Engines shipped over a 3 month periodat aircraft engine factory C

0

1

2

3

4

5

6

7

may june july augustweeks

enginesshipped

Factory C

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On-time performance of engine

plants

A B C0%

20%

40%

60%

80%

100%

enginesdelvered

A B C

on

time

late

on

time

on

time

late

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Push and Pull Systems

Machines

Parts Orders

1 2 3 4