just-in-time (jit) production system
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JUST-IN-TIME (JIT) PRODUCTION SYSTEM
The name just-in-time refers to a production system in which operations (processing, movement of materials & goods, etc.) occur just as they are needed or demanded. JIT approach emphasizes continual effort to remove waste & inefficiency from the production process through small lot sizes, high quality, and teamwork.
MISUNDERSTANDINGS ABOUT JUST-IN-TIME
• Different JIT Systems
• JIT means “zero stock”
• Impossible to implement in Pakistan
• Only good for manufacturing concerns
• Inner & outer dimensions
Key Elements of JIT Systems
•A fixed, steady rate of production•Low inventories •Small lot sizes•Quick, low-cost setups•Layout•Preventive maintenance & repair•Multifunctional workers
Key Elements of JIT Systems
•High quality levels•A cooperative spirit•Reliable vendors•A pull system of moving goods•Problem solving•Continual improvement
Kanban
Definition: A “kanban” is a sign-board or card in Japanese and is the name of the flow control system developed by Toyota.
Role:
Kanban is a tool for realizing just-in-time. For this tool to work fairly well, the production process must be managed to flow as much as possible. This is really the basic condition. Other important conditions are leveling production as much as possible and always working in accordance with standard work methods.
– Ohno 1988
Push vs. Pull: Kanban is a “pull system”
– Push systems schedule releases
– Pull systems authorize releases
MRP versus Kanban
…
Lover Level Inventory
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MRP
Kanban
…
Kanban Signals Full Containers
Lover Level
InventoryAssembly
Assembly
Kanban Mechanism
Outbound stockpoint
Outbound stockpoint
Productioncards
Completed parts with cards enter outbound stockpoint.
When stock is removed, place production card in hold box.
Production card authorizes start of work.
Benefits of JIT Systems
• Reduced levels of in-process inventories, purchased goods, and finished goods• Reduced space requirements• Increased product quality & reduced scrap & rework• Reduced manufacturing lead times• Greater flexibility in changing the production mix
Benefits of JIT Systems
•Smoother flow of production, with fewer disruptions caused by problems due to quality; shorter setup times; multi skilled workers who can help each other & substitute for others in case of absenteeism•Increased productivity levels & utilization of equipment•Worker participation in problem solving
Benefits of JIT Systems
•Pressure to build good relationships with vendors
•Reduction in the need for certain indirect labor, such as material handlers
Converting to a JIT System
Top management must be committed to the conversion and that they know what will be required. Furthermore, management must be willing to provide visible support.
Management must know what it will cost & how long it will take to complete the conversion, and what results can be expected.
Converting to a JIT System
•Study the operations carefully; decide which parts will need the most effort to convert
•Obtain the support & cooperation of workers
•Begin by trying to reduce setup times while maintaining the current system
Converting to a JIT System
•Gradually convert operations, beginning at the end of the process & working backward. At each stage, make sure the conversion has been relatively successful before moving on.
•Do not begin to reduce inventories until major problems have been resolved.
•Convert suppliers to JIT as one of the last steps
Converting to a JIT System
•Prepare to work closely with suppliers. Start by narrowing the list of vendors, identifying those who are willing to embrace the JIT philosophy
•Try to use vendors located nearby if quick response time is important
•Insist on high standards of quality & adherence to strict delivery schedules
Obstacles to Conversion
•Management may not be totally committed or may be unwilling to devote the necessary resources to conversion
•Workers may not display a cooperative spirit
•Management may resist because JIT shifts some of the responsibility from management to the workers
Obstacles to Conversion
Suppliers may resist, for several reasons:•Buyers may not be willing to commit the resources necessary to help the supplier adapt to the JIT system
•They may be uneasy about long-term commitments to a buyer
•Frequent, small deliveries may be difficult, especially if the supplier has other buyers that are not using JIT systems
Obstacles to Conversion
•The burden of quality control will shift to the supplier
•Frequent engineering changes may have to be made as the result of continuing JIT improvements on the part of the buyer
Why is “Zero Defects” an Important Concept?
Key Element in our capability to implement Kaizen
Manufacturing Systems.
No need for “just in case” inventories
Allows company to make only what the
customer needs.
What is a Zero Defect Quality System (ZDQ)?
A quality concept to manufacture ZERO defects & elimination of waste associated with defects!
“ZERO” is the goal!
1-10-100 Rule
$1000
The 1-10-100 rule states that as a product or service moves through the production system, the cost of correcting an error multiplies by 10.
Activity Cost
Order entered correctly $ 1
Error detected in billing $ 10
Error detected by customer $ 100
Dissatisfied customer shares the experience with others the costs is
Source Inspection
Detects mistakes before they become defects
Transformation = Quality production the 1st time
Inspection….eliminated ???
Transport
Storage
Delay/wait
Dedicated lines
One piece flow