COST VS
DEFECTS
Introduction to the Toyota
Production System (TPS)
2.810
T. Gutowski
Nov 3, 2014
1
Three Major Mfg Systems
from 1800 to 2000
Machine tools, specialized machine tools, Taylorism, SPC, CNC, CAD/CAM
1800
Interchangeable
Parts at U.S.
Armories
1900
Mass
Production
at Ford
2000
Toyota
Production
System
1980s OPEC oil
embargo drives
up fuel prices,
Japanese
imports small
cars with increased
fuel mileage
3
Consumer Reports
How we learned about TPS
Quality of cars - but not right away
Pilgrimages - Hayes, Wheelwright, Clark
Joint ventures - Nummi-Geo
Japanese NA operations-Georgetown, KY
Japanese sages- Ohno, Shingo, Monden
American translation- Lean, J T. Black..
Consulting firms-Shingjutsu,
5
Toyota Production System Development History - Taiichi Ohno
30 years of development 1945 to 1975
6
Translation: there is no
Silver Bullet.
REFERENCES ON THE TOYOTA
PRODUCTION SYSTEM;
Taiichi Ohno, The Toyota Production
System Productivity Press 1988
Shigeo Shingo, A Study of the Toyota
Production System Productivity Press
1989
Yasuhiro Monden, Toyota Production
System, 1st Ed 1983
Hayes, Wheelwright and Clark,
Dynamic Manufacturing Free Press
1988
Womack and Jones, Lean Thinking
Simon and Schuster, 1996
1990
Performance Observations
Early observations of reliability, after some
initial start-up problems
IMVP got actual factory level data 1980s
defect counts
direct labor hours for assembly
level of automation
Summary of Assembly Plant Characteristics, Volume Producers,
1989
(Average for Plants in Each Region)
Perf ormance:
Producv itity (hours/Veh.)
Quality (assembly
def ects/100 v ehicles)
Lay out:
Space (sq.f t./v ehicle/y r)
Size of Repair Area (as %
of assembly space)
Inv entories(day s f or 8
sample parts)
Work Force:
% of Work Force in Teams
Job Rotation (0 = none,
4 = f requent)
Suggestions/Employ ee
Number of Job Classes
Training of New Production
Workers (hours)
Absenteeism
Automation:
Welding (% of direct steps)
Painting(% of direct steps)
Assembly (% of direct steps)
Japanese
Japanese in
American in
in Japan
North America
North America
All Europe
16.8
21.2
25.1
36.2
60
65
82.3
97
5.7
9.1
7.8
7.8
4.1
4.9
12.9
14.4
0.2
1.6
2.9
69.3
71.3
17.3
0.6
3
61.6
11.9
2.7
1.4
8.7
0.9
0.4
67.1
1.9
0.4
14.8
380.3
5
370
4.8
46.4
11.7
173.3
12.1
86.2
54.6
1.7
85
40.7
1.1
76.2
33.6
1.2
76.6
38.2
3.1
Source: IMVP World Assembly Plant Surv ey , 1989, and J. D. Power Initial Quality Surv ery , 1989
10
Cost Vs Defects
Ref. Machine that Changed the World Womack, Jones and Roos
11
Cost Vs Automation
Ref. Machine that Changed the World Womack, Jones and Roos
12
History of the Development of the Toyota
Production System
ref; Taiichi Ohno
1945
1975
inventory
set-up
cells
Andon
13
Basic Goal
To reduce cost by Elimination of waste
Excessive production resources
Overproduction
Excessive inventory
Unnecessary capital investment
See Toyota Production System, Yasuhiro Monden
14
Simulation of a 20 machine, 19 buffer (cap = 10 parts)
Transfer line. Each machine with one minute cycle time
could produce 4800 parts per week. MTTF 3880 minutes,
MTTR 120 minutes. See Gershwin p63-64
Perfect machines, buffer
buffer
Ave (3249 sim, 3247 analy)
Zero buffer
N* 240 parts
15
Buffer capacity Vs MTTR
10 parts X 1minute/part = 10 minutes
MTTR = 120 minutes
N* ~ 240 or more parts X how many
buffers?
This is clearly unacceptable!
CHANGE THINKING, REDUCE VARIATION
16
What causes variation?
Quality issues
Delivery time issues
Unavailable resources issues
17
What causes variation?
Quality issues
Check quality, prevent propagation
Delivery time issues
JIT
Unavailable resources issues
Flexible machines and cross trained workers
18
Quality Issues
Make quality problems obvious
Error checking (Pokeyoke), Pull system
Reduce WIP, which hides problems
Stop the line
Fix it now
Cooperative problem solving
19
Delivery Time Issues
With low inventories we can not pull from a
warehouse
Production to the beat, (Takt Time)
Toyota Cells
Parts need to be there when you need
them - (issues with long distances)
Just in Time (JIT)
20
Unavailable Resource Issues
Fast set up
Single Minute Exchange of Dies (SMED)
Flexible (general purpose) machines
Toyota Cells
Cross-trained work force
21
Autonomation
Monden claims that the word autonomation comes from the Japanese word Jidoka. which
has two meanings, the first is automation in the usual sense, to change from a manual process
to a machine process. The second meaning is automatic control of defects. He says this is
the meaning coined by Toyota. This second meaning is sometimes referred to as Ninbennoaru
Jidoka, which literally translates into automation with a human mind. Monden goes on to say
that although autonomation often involves some kind of automation, it is not limited to
machine processes but can be used in conjunction with manual operations as well. In either
case, it is predominantly a technique for detecting and correcting production defects and
always incorporates the following devices; in mechanism to detect abnormalities or defects; a
mechanism to stop the line or machine when abnormalities or defects occur. When a defect
occurs, the line stops, forcing immediate attention to the problem, an investigation into its
causes, and initiation of corrective action to prevent similar defects from occurring again
Reference; Yasuhiro Monden, Toyota Production System,
22
J T. Blacks 10 Steps
Ref; JT. Black Factory with a Future 1991
1.
2.
3.
4.
5.
6.
7.
8.
9.
Form cells
Reduce setup
Integrate quality control
Integrate preventive maintenance
Level and balance
Link cells KANBAN
Reduce WIP
Build vendor programs
Automate
10. Computerize
23
J T. Black 1, 2
1. Form Cells
Sequential
operations, decouple
operator from
machine, parts in
families, single piece
flow within cell
2. Reduce Setup
Externalize setup to
reduce down-time
during changeover,
increases flexibility
24
Toyota Cell, one part is produced
for every trip around the cell
TPS Cell
J T. Black
25
J T. Black 3, 4
3. Integrate quality
control
Check part quality at
cell, poke-yoke, stop
production when
parts are bad, make
problems visible,
Andon
4. Integrate preventive
maintenance
worker maintains
machine , runs
slower, operator owns
production of part
26
J T. Black 5, 6
5. Level and balance
Produce to Takt
time, reduce batch
sizes, smooth
production flow,
produce in mix to
match demand
6. Link cells- Kanban
Create pull system
Supermarket
System that
indicates the status
of the system
27
Balancing and Leveling
Balanced line: each process has the same
cycle time. Match process time to
assemble time, match production rate to
rate of demand (Takt time)
Leveled Line: each product is produced in
the needed distribution. The process must
be flexible to do this.
28
J T. Black 7, 8
7. Reduce WIP
Make system reliable,
build in mechanisms
to self correct
8. Build Vendor
program
Propagate low WIP
policy to your
vendors, reduce
vendors, make ontime performance part
of expectation
29
TPS Cell
1. Work flow (part separate from worker)
2. Standard work (highly specified)
3. Production rate flexibility
30
Machining Cell
Operator moves part
from machine to machine
(including decouplers)
by making traverse
around the cell.
31
Cell Features
Synchronized, sequential production
Operator decoupled from individual
machines
Operator integrated into all tasks
Goal: single piece Flow
Best with single cycle automatics, but can
be done manually too
See Video
32
Walking segments - 10
Machining Cell
segment
Manual
(Sec)
Walk to
(Sec)
Machine
(Sec)
Raw
Saw
15
60
L1
10
70
L2
12
50
HM
12
120
VM1
20
70
VM2
20
60
15
60
F.I.
19
10
Finish
part
Totals
8
9
3
2
10
1
3
M+W
= 153
490
33
Parts in the cell ~ 14
Machining Cell
Manual
(Sec)
Raw
Walk to
(Sec)
Machine
(Sec)
Saw
15
60
L1
10
70
L2
12
50
HM
12
120
VM1
20
70
VM2
20
60
15
60
F.I.
19
3+3
Totals
M+W
= 153
9
14
10
11
12
13
2
1
490
34
Standard Work for Cell
PART:
JT. Black Cell
PROCESS
#
OPERATION
1 Raw
2 Saw
3 L1
4 L2
5 HM
6 VM1
7 VM2
8G
9 F.I.
Operators:
TIME {secs}
Man Walk Auto
3
15
3
60
10
3
70
12
3
50
12
3 120
20
3
70
20
3
60
15
3
50
19
6
20
40
60
80
100
120
140
160
180
Cell produces one part every 153 sec
Note: machine time Max (MTj) < cycle time CT
i.e. 120+12 < 153
35
TPS Cell
1. Production rate =
1part
23.5 parts/hr
153 sec
2. WIP = L?
3. Time in the system = W?
36
TPS Cell and Littles Law
L = W, we know L and , what is W?
Define System Boundaries
Follow part around the cell
Single operator case
37
Number of round trips; 13
Machining Cell
6
Saw
3+15
+ 153
#1
decoupler
1.5
+153
L1
1.5+
10
+153
Grind
1.5+
15
+153
Manual
and walk
19+3
out
150
153X13
=1989
10
11
12
13
2
1
1989 + 150 = 2139
38
By Littles Law
L = (13 + 1) X (150/153) +
13 X (3/153) = 13.98 parts
rate, = 1/153 parts/second
W = 153 X 13.98 = 2139 sec
39
TPS Cell
Increase production rate:
a) add additional worker to cell
b) modify machine bottlenecks
40
Manual
(Sec)
Raw
Walk to
(Sec)
Machine
(Sec)
To increase production rate add 2nd worker
Saw
15
60
L1
10
3+3
70
L2
12
50
HM
12
120
VM1
20
70
VM2
20
3+3
60
15
60
F.I.
19
3+3
Totals
M+W
= 159
Work 1
80
Work 2
79
WORKER 2
WORKER 1
490
41
What is the production rate for
this new arrangement?
Check max(MTj) < CT
Worker 1;
80 = 80
Worker 2;
12+120 >79
One part every 132 seconds
We are limited by the HM (horizontal mill)
1part
27.3 parts/hr
132 sec
Can we shift work off of the HM to reduce the cycle time?
42
Manual
(Sec)
Raw
Walk to
(Sec)
Machine
(Sec)
Saw
15
60
L1
10
3+3
70
L2
12
50
HM
12
120
WORKER 2
80
VM1
20
70
80
VM2
20
3+3
WORKER 1
60
90
15
F.I.
19
3+3
Totals
M+W
= 159
Work 1
80
Work 2
79
60
490
43
Standard Work for Worker #2
Rod Support
PROCESS
OPERATION
from decoupler
L2
HM
VM1
VM2
Operators: Worker #2
TIME {secs}
Man Walk Auto
1.5
12
3
50
12
3
80
20
3
80
20 1.5
90
20
40
Cycle # 1
60
80
100
120
140
160
180
Cycle # 2
+3
Operator waiting
On machine
44
What is the new production
Rate?
Check max(MTj) < CT
Worker 1;
80 = 80
Worker 2;
110 > 79
Hence Worker #2 will be waiting on
Vertical Mill #2
45
What is the new production
Rate?
The new production rate is;
one part every 110 sec
Pro and Cons; Worker idle, cant speed
up by adding additional worker
Design for flexibility make;
Max(MTj) < CT/2
1part
32.7 parts/hr
110 sec
46
Manual
(Sec)
Raw
Walk to
(Sec)
Machine
(Sec)
Saw
15
60
L1
10
3+3
70
L2
12
50
HM
12
120
VM1
20
70
VM2
20
3+3
60
15
60
F.I.
19
3+3
Totals
M+W
= 159
Work 1
80
Work 2
79
Alternative solution add 2 HMs
WORKER 2
WORKER 1
490
1part
40 parts/hr
90 sec
Almost double!
47
TPS cell summary
1.
2.
3.
4.
Original cell Additional worker+ Shift work++ add additional VM
23.5 parts/hr
27.3 parts/hr
32.7 parts/hr
40 parts/hr
48
TPS Implementation
Physical part (machine placement,
standard work etc)
Work practices and people issues
Supply-chain part
Corporate Strategy (trust, job security)
49
Work practices and people
issues
Failed TPS attempts; GM Linden NJ,
CAMI, GM-Suzuki, Ontario Canada.
Successes GM NUMMI, Saturn. Toyota
Georgetown, KY
Maccoby HBR 1997
Other Ref: Just Another Car Factory Rinehart, Huxley and
Robertson, Farewell to the Factory, Milkman
50
According to Maccobys Review
failures at middle management
pressure from above to meet targets, lack
of trust from below, but
both plants adopted some aspects of lean,
and
both plants improved
51
NUMMI and Georgetown
workers have different attitude
do not fear elimination
play important role
...go to Georgetown and find out
52
NUMMI plant today - Tesla
53
The DNA of the TPS
Spear and Bowen
4 years 40 plants
HBR Sept-Oct 1999
Four Rules
1.
2.
3.
4.
How people work
How people connect
How the production line is constructed
How to improve
54
Four Rules
Rule 1: All work shall be highly specified as to content, sequence, timing
and outcome.
Rule 2: Every customer-supplier connection must be direct, and there must
be an unambiguous yes-or-no way to send requests and receive responses.
Rule 3: The pathway for every product and service must be simple and
direct.
Rule 4: Any improvement must be made in accordance with the scientific
method, under the guidance of a teacher, at the lowest possible level in the
organization.
Spear and Bowen
55
TPS Summary
High quality and low cost paradigm shift
Many elements to the system
Make system observable
Produce to demand
Study defects and eliminate
Institutionalize change
Trust
Many companies have imitated TPS
56
Key Elements for New Mfg Systems
Element/
System
Need of
Society
Resources
Work
Force
Motivation
Enabling
Technology
Leader
Interchange- Military
able Parts
Yankee
Ingenuity
Machine
Tools,
Division of
Labor
Roswell U.S.
Lee/
Govt
John
Hall
Mass
Production
Transportation
$5/day
Immigrant
Moving
Assembly
Line,etc
Henry
Ford
Earnings
Toyota
Production
System
Post War Jobs,
Security
Systems
approach
Taiichi
Ohno
Japanese
Banks
57
Readings
James Womack, Daniel T. Jones and Daniel Roos,
The Machine that Changed the World, 1990, Ch 3 and 4
J T. Black The Factory with a Future Ch 2 & 4
Michael Maccoby, Is There a Best Way to Build a Car?
HBR Nov-Dec 1997
58
