14-1 JIT and Lean Operations
Operations Management
William J. Stevenson
8th edition
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14-2 JIT and Lean Operations
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14-3 JIT and Lean Operations
JIT/Lean Production
Just-in-time (JIT): A highly coordinated
processing system in which goods move
through the system, and services are
performed, just as they are needed,
JIT lean production
JIT pull (demand) system
JIT operates with very little “fat”
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Goal of JIT
The ultimate goal of JIT is a balanced
system.
Achieves a smooth, rapid flow of
materials through the system
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Summary JIT Goals and Building
14-5 JIT and Lean Operations
Blocks
Figure 14.1
Ultimate A
Goal balanced
rapid flow
Supporting
Goals Eliminate disruptions
Make the system flexible Eliminate waste
Product Process Personnel Manufactur- Building
Design Design Elements ing Planning Blocks
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Supporting Goals
Eliminate disruptions
Make system flexible
Eliminate waste, especially excess
inventory
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Sources of Waste
Overproduction
Waiting time
Unnecessary transportation
Processing waste
Inefficient work methods
Product defects
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Big vs. Little JIT
Big JIT – broad focus
Vendor relations
Human relations
Technology management
Materials and inventory management
Little JIT – narrow focus
Scheduling materials
Scheduling services of production
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JIT Building Blocks
Product design
Process design
Personnel/organizational
elements
Manufacturing
planning and control
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Product Design
Standard parts
Modular design
Highly capable production systems
Concurrent
engineering
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Process Design
Small lot sizes
Setup time reduction
Manufacturing cells
Limited work in process
Quality improvement
Production flexibility
Little inventory storage
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Benefits of Small Lot Sizes
Reduces inventory
Less rework
Less storage space
Problems are more apparent
Increases product flexibility
Easier to balance operations
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Production Flexibility
Reduce downtime by reducing
changeover time
Use preventive maintenance to
reduce breakdowns
Cross-train workers to help clear
bottlenecks
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Production Flexibility (cont’d)
Use many small units of capacity
Use off-line buffers
Reserve capacity for important customers
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Quality Improvement
Autonomation
Automatic detection of defects during production
Jidoka
Japanese term for autonomation
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Personnel/Organizational Elements
Workers as assets
Cross-trained workers
Continuous
improvement
Cost accounting
Leadership/project
management
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Manufacturing Planning and Control
Level loading
Pull systems
Visual systems
Close vendor relationships
Reduced transaction
processing
Preventive maintenance
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Pull/Push Systems
Pull system: System for moving work
where a workstation pulls output from
the preceding station as needed. (e.g.
Kanban)
Push system: System for moving work
where output is pushed to the next
station as it is completed
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Kanban Production Control System
Kanban: Card or other device that
communicates demand for work or
materials from the preceding station
Kanban is the Japanese word meaning
“signal” or “visible record”
Paperless production control system
Authority to pull, or produce comes
from a downstream process.
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Kanban Formula
DT(1+X)
N =
C
N = Total number of containers
D = Planned usage rate of using work center
T = Average waiting time for replenishment of parts
plus average production time for a
container of parts
X = Policy variable set by management
- possible inefficiency in the system
C = Capacity of a standard container
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Traditional Supplier Network
Figure 14.4a
Buyer
Buyer
Supplier
Supplier Supplier
Supplier
Supplier
Supplier
Supplier
Supplier Supplier
Supplier Supplier
Supplier Supplier
Supplier
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Tiered Supplier Network
Figure 14.4b
Buyer
Buyer
First Tier Supplier Supplier
Supplier
Second Tier Supplier Supplier
Supplier Supplier
Supplier
Third Tier Supplier Supplier
Supplier Supplier
Supplier Supplier
Supplier Supplier
Supplier
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Comparison of JIT and Traditional
Table 14.3
Factor Traditional JIT
Inventory Much to offset Minimal necessary to
forecast errors, late operate
deliveries
Deliveries Few, large Many, small
Lot sizes Large Small
Setup; Few, long runs Many, short runs
runs
Vendors Long-term Partners
relationships are
unusual
Workers Necessary to do the Assets
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Transitioning to a JIT System
Get top management commitment
Decide which parts need most effort
Obtain support of workers
Start by trying to reduce setup times
Gradually convert operations
Convert suppliers to JIT
Prepare for obstacles
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Obstacles to Conversion
Management may not be committed
Workers/management may not be
cooperative
Suppliers may
resist
Why?
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JIT in Services
The basic goal of the demand flow technology in
the service organization is to provide optimum
response to the customer with the highest
quality service and lowest possible cost.
Eliminate disruptions
Make system flexible
Reduce setup and lead times
Eliminate waste
Minimize WIP
Simplify the process
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JIT II
JIT II: a supplier representative works
right in the company’s plant, making
sure there is an appropriate supply on
hand.
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Benefits of JIT Systems
Reduced inventory levels
High quality
Flexibility
Reduced lead times
Increased productivity
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Benefits of JIT Systems (cont’d)
Increased equipment utilization
Reduced scrap and rework
Reduced space requirements
Pressure for good vendor relationships
Reduced need for indirect labor
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Elements of JIT
Table 14.4
Smooth flow of work (the ultimate goal)
Elimination of waste
Continuous improvement
Eliminating anything that does not add
value
Simple systems that are easy to manage
Use of product layouts to minimize
moving materials and parts
Quality at the source
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Elements of JIT (cont’d)
Table 14.4
Poka-yoke – fail safe tools and methods
Preventative maintenance
Good housekeeping
Set-up time reduction
Cross-trained employees
A pull system
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