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
Supplier A Supplier B
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JIT Layout with Group Technology
FinalAssembly
Supplier A Supplier B
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
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