Transcript Document

Matching Supply with Demand:
An Introduction to Operations Management
Gérard Cachon
ChristianTerwiesch
All slides in this file are copyrighted by Gerard Cachon and Christian
Terwiesch. Any instructor that adopts Matching Supply with
Demand: An Introduction to Operations Management as a required
text for their course is free to use and modify these slides as desired.
All others must obtain explicit written permission from the authors to
use these slides.
Zero non-value added
activities (muda)
8.2
Zero defects, zero breakdowns, zero inventory, zero set-up
Production flow synchronized with demand (JIT)
Quality methods to reduce defects
One-unit-at-a-time flow
Fool-proofing (poka-yoke) and visual feed-back
Mixed model production (heijunka)
Detect-stop-alert (Jidoka)
8.4
8.5
Piece-by-piece transfer (ikko-nagashi)
Defects at machines (original Jidoka)
Match production demand based on Takt time
Defects in assembly (Andon cord)
Pull instead of push
Build-in-quality (tsukurikomi)
Supermarket / Kanban
Make-to-order
Reduce inventory to
expose defects
8.6
Flexibility
Adjustment of capacity to meet takt-time
Multi-task assignment (takotei-mochi)
8.7
Standardization of work
Reduction of Variability
Quartile Analysis
Standard operating procedures
8.8
Worker involvement
Quality circles (Kaizen)
Fishbone diagrams (Ishikawa)
Skill development / X-training
8.9
100
Improvement potential
> 300%
55
45
30
Total
planned
up-time
Breakdown
Changeovers
Downtime losses
Availability rate
55 %
AvailIdling
able time and minor
stop-pages
X
Re-duced
Speed
(quartile
plot)
Speed losses
Performance rate
82 %
Net
operating
time
X
Defects
Start-up
Quality losses
Quality rate
67 %
OEE
= OEE
30 %
Direction of production flow
upstream
downstream
Authorize
production
of next unit
Figure 8.13.: Simplified mechanics of a Kanban system
7
8
5
4
6
3
1
Defective unit
2
Good unit
ITAT=7*1 minute
4
1
3
2
ITAT=2*1 minute
Figure 8.12.: Information turnaround time and its relationship with buffer size
Buffer argument:
“Increase inventory”
Inventory
in process
Toyota argument:
“Decrease inventory”
Figure 8.14.: More or less inventory? A simple metaphor
Flow Rate
High
Increase inventory
(smooth flow)
Path advocated by
Toyota production system
Now
Reduce inventory
(blocking or starving
become more likely)
New frontier
Frontier reflecting
current process
Low
High Inventory
(Long ITAT)
Low Inventory
(short ITAT)
Inventory
Figure 8.15.: Tension between flow rate and inventory levels / ITAT