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Introduction to JIT
Overview of JIT
JIT is a pull production system
Catch Phrase
“The right part in the right place at the right
time”
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History of JIT
Taiichi Ohno of the Toyota Motor Corporation
is often referred to as “The Father of JIT.” The
JIT management philosophy has been around
since the 1950’s, which is when Ohno first
started developing and practicing JIT concepts
within the Toyota Corporation. Ohno titled his
new methods of production the Toyota
Production System (TPS), which has now
become a synonymous term for JIT
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Toyota’s Lean Production House
Goal: highest quality, lowest cost, shortest leadtime
Heijunka 5S Standardized Work Kaizen
Jidoka
Just in Time (JIT) –
continuous flow, pull
system, or kanban
JIT
Stability – Stable Manufacturing Processes, 100% Quality, Total Preventative Maintenance
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Synonyms for JIT
Toyota Production System
Stockless production
Lean production
Kanban system
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JIT Goal and Philosophies
GOAL of JIT:
Production control through waste elimination
Philosophy of JIT
Elimination of waste
Broad view of operations
Simplicity
Continuous improvement
Visibility
Flexibility
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Elements of JIT
Meet daily
Discuss work practices
Reduce buffer stock
Modify machinery –
reduced setup
Reveal non-value added
practices
Involve the workforce:
consultation instead of
confrontation
Expose problems
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Benefits of JIT
Better quality products
Reduced scrap and rework
Reduced cycle times
Lower setup times
Smoother production flow
Cost savings
Less inventory
Higher productivity
Most skilled workforce
Reduced space
requirements
Higher work participation
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Canon’s Nine Wastes
Work-in-process
Defects
Equipment
Expense
Indirect labor
Planning
Human resources
Operations
Startup
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The Five Why’s
Ask “Why” five times to get to the source
of waste and the cause of problems
1. Why did the machine stop? Overload and
blown fuse
2. Why the overload? Not lubricated
3. Why not lubricated? Oil pump not pumping
4. Why not pumping? Pump shaft worn out
5. Why worn out? No screen, scrap was let in
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Push vs. Pull
Push System
Material is pushed downstream and inventory
builds regardless of resource availability
Strong emphasis on production first
Stock points and additional inventory can
overflow with parts and raw materials
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Traditional Push Production System
• Huge lot sizes
• Lots of inventory
• “Push” material to
next stage
Big purchase
shipments w/
lower per
unit shipping
cost
Big “pushes”
of finished
goods to
warehouse or
customers
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Pull vs. Push
Pull System
The customer starts the production process by
pulling production when it is needed
Material is moved to workstations as it is
needed
Stock points are kept at a minimum
Waste is MINIMIZED
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Pull Production System
• Smaller lots
• Faster setups
• Less inventory
Smaller
shipments w/
minimal /
no inventory
holding cost
Goods are
“pulled” by
demand out
of the plant
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Necessary Conditions For Pull
1. Planning and Control Responsibility
2. Producing to Meet Demand
3. Reduce In-Process Inventories
4. Preventative Maintenance
5. Quality Assurance
6. Setup Times Must be Small
7. Linking of All Operations
8. Production Plans and Schedules Must Be
Uniform
9. Develop Cooperative Attitudes and Teamwork
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Achieving Pull Production
Pull System as Reorder Point (ROP) System
D = demand (consumption rate)
LT = lead time (elapsed time btwn order and
replenishment
P = production time
C = conveyance time (time to convey order to
upstream process, plus time to move materials to the
downstream operation
SS = safety stock (number of parts)
SS
LT
D
ROP
)
(
C
P
LT
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Achieving Pull Production
Standard-Sized Containers
If Q = the capacity of a standard container, then
ROP as expressed in terms of the number of
containers is K, or the maximum number of
completely full containers in a buffer
Container Size
Container should hold about 10% of the daily
demand
Q
C
P
D
K
)
(
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Kanban
Kanban card shows typical production
quantity
Derived from two-bin inventory system
Maintains pull production system
A production kanban authorized production
A withdrawal kanban authorizes material
handling
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Kanban Pre-Conditions
There are four
pre-conditions for
the successful
implementation of
Kanban
Point of use
inclusion (all parts
on the assembly line)
Level production
Stabilized processes
Quick Changeover
procedures
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Kanban
Kanban means “signboard”
Kanban is a signal used to communicate
production cues in a pull production system
A
B
Storage
Machine Center Assembly Line
Production
Kanban
Withdrawal
Kanban
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Sample Kanban Card
Part No.: 6934
Description: Servo motor
Box capacity: 30
Box type: AF
Issue No.: 06
To:
Station
D-7
Assembly
3
From:
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Sample Kanban Card
Market Address
<<Market_Address>>
Kanban Number
<<Kanban_Number>>
Line-Side Address
<<Line_Side_Address>>
Part Number
<<Part Number>>
Route
<<Route>>
Part Description
<<Part Number>>
Bar Code Area
Dock Code
<<Dock Code>>
Supplier Code
<<Supplier Code >>
Quantity
<<Quantity>>
Serial Number
Comment:
<<Comment>>
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Conveyance Kanbans
A conveyance kanban, or C-kanban,
authorizes containers to move from an
upstream, outbound buffer to a downstream,
inbound buffer
Kc = number of C-kanbans
C = total time between when workers remove a C-kanban
from a full container at the inbound buffer and when
they remove a C-kanban from the next full container
Q
C
D
Kc
)
(
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Production Kanbans
P-kanban is used to authorize production
parts to assemblies
Kp = number of P-kanbans
P = total time elapsed from when workers or mat’l
handlers remove the P-kanban from a full container and
post it at the outbound buffer until the time they remove
the P-kanban from the next full container
Q
P
D
Kp
)
(
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1 & 2-Card Kanban Systems
1-card systems use only C-kanbans
2-card systems use both C-kanbans and P-
kanbans
