Post on 28-Dec-2015
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JIT – Just-In-Time Production
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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
JidokaJust 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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JIT Principles
SimplificationCleanliness and organizationVisibilityCycle timingAgilityVariation reductionMeasurement
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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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Toyota’s Seven Wastes
Producing defects
Transportation
Inventory
Overproduction
Waiting Time
Processing
Motion
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Canon’s Nine Wastes
Work-in-processDefectsEquipmentExpenseIndirect laborPlanningHuman resourcesOperationsStartup
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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 purchaseshipments w/
lower perunit shipping
cost
Big “pushes”of finished
goods towarehouse 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
Smallershipments w/
minimal /no inventoryholding cost
Goods are“pulled” by
demand outof 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 timeC = conveyance time (time to convey order to
upstream process, plus time to move materials to the downstream operation
SS = safety stock (number of parts)
SSLTDROP )(
CPLT
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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
CPDK
)(
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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 Point of use inclusion (all parts inclusion (all parts on the assembly line)on the assembly line)
Level productionLevel production
Stabilized processesStabilized processesQuick Changeover Quick Changeover proceduresprocedures
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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
ProductionKanban
WithdrawalKanban
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Sample Kanban Card
Part No.: 6934Description: Servo motor
Box capacity: 30Box type: AFIssue No.: 06
To:
StationD-7
Assembly3
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 bufferKc = 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
CDKc
)(
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Production Kanbans
P-kanban is used to authorize production parts to assembliesKp = 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
PDKp
)(
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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
DISCUSSION
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