Just-In-Time Systems

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Chapter 16

• Just-In-Time Systems

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JIT/Lean Production

• Repetitive production system in which processing
  and movement of materials and goods occur just as
  they are needed, usually in small batches
• JIT is characteristic of lean production systems
• A JIT system operates with very little fat

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JIT Goals

• Eliminate disruptions to the system
• Make the system flexible
• Reduce setup and lead times
• Minimize inventory in the system
• Eliminate waste in the system

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Sources of Waste

• Waste from overproduction
• Waste of waiting time
• Transportation waste
• Inventory waste
• Processing waste
• Waste of motion
• Waste from product defects

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JIT Building Blocks

• Product design
• Process design
• Personnel/organizationalelements
• Manufacturing planning and control

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Product Design

• Incorporate standard parts when possible
• Modular design
• Highly capable production systems

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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
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Production Flexibility

• Reduce downtime for an operation by reducing
  changeover time
• Use preventive maintenance to reduce the chance
  of random breakdowns
• Cross-train workers to help clear bottlenecks
• Reserve capacity for important customers

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Personnel/Organizational Elements

• Workers regarded 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 (material)
  where a workstation pulls output from the
  preceding station only as it is needed
• Push system System for moving work where output
  is pushed to the next station as it is completed
  (e.g. MRP)

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Kanban Production Control System

• A visible signal is used to notify the supplier
  (or supplying department) of the need for more
  material
• This results in a pull system
• Supply batches are usually very small
• requires tight production/delivery schedules and
  frequent setups
• Any inventory shortage, quality problem or
  process failure has immediate impact

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Ideal Number of Kanban Cards
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Traditional Supplier Network
Figure 16-3a
Buyer
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Tiered Supplier Network
Buyer
Figure 16-3b
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Summary JIT Goals and Building Blocks
Figure 16-4
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Benefits of JIT Systems (1 of 2)

• Reduced levels of inventories
• Reduced space requirements
• Increased product quality
• Reduced lead times
• Greater flexibility in product mix

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Benefits of JIT Systems (2 of 2)

• Smoother production flow
• Increased productivity levels
• Worker participation in problem solving
• Pressure for good vendor relationships
• Reduced need for indirect labor

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Converting 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

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JIT in Service

• 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 the practice of allowing vendors to
  manage some aspects of buying their products or
  services for the buyer