Just-In-Time Systems

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Just-In-Time Systems
Where to Focus pp 482 - 492
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TQM and JIT

• 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 program emphasizes quality at the source
• Also known as Lean Manufacturing
• Pull method of materials flow
• Less inventory to hide defective items
• Smooth production rates result in less rushing
  and fewer errors

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JIT Goals and Building Blocks
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Pull Systems

• Pull system System for moving work where a
  workstation pulls output from the preceding
  station as needed. (e.g. Kanban)

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Organization Wide Commitment to JIT

• Elimination of Waste and Variance
• Waste anything that does not add value to the
  product
• Can no longer have
• Faulty components from suppliers
• Poorly trained and improperly selected employees
• Poor condition of equipment
• Badly targeted performance measures
• Inadequate capacity
• Damage in shipping and storage

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Estimated Benefits

• 80 to 90 reduction in inventory investment
• 80 to 90 reduction in manufacturing lead times
• 75 reduction in rework and setup
• 50 reduction in space requirements
• 50 reduction in materials handling equipment

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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
• Visibility cards, lights, less inventory
• Authority to pull, or produce comes from a
  downstream process.

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Inventory Reduction Goals

• Material is always moving, always being worked
  on, always having value added to it, rather than
  just standing still.. accumulating costs

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Scheduling
Where to Focus pp 770 - 784
Time
Jobs
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Manufacturing Execution Systems

• Used by fortune 500 manufacturers to link and
  integrate MRP systems with shop floor systems
• Provides real time operational information
• Benefits include reduced cycle times, shorter
  lead times, reduced WIP, and improved on-time
  delivery performance

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Manufacturing Process
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Scheduling

• Scheduling Establishing the timing of the use of
  equipment, facilities and human activities in an
  organization
• Effective scheduling can yield
• Cost savings
• Increases in productivity

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Performance Measures

• Job flow time Time of completion - Time job was
  available for first processing
• Makespan Time of completion of last job -
  Starting
• time of first job
• Past due
• amount of time job missed due date

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Performance Measures

• Work-in-process inventory
• job in waiting line, moving, delayed, or
  processed
• Total inventory Scheduled receipts for all
  items On-hand inventories of all items
• Utilization Productive work time/Total work
  time available

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Dispatching Procedures

• Earliest due date
• First come, first served
• Shortest processing time

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Sequencing
Single-Dimension Rules - EDD
Average job flow time 23 hours
Average hours early 0.6 hours
Average hours past due 7.2 hours
Average WIP 2.61 returns
Average total inventory 2.68 returns
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Sequencing
Single-Dimension Rules - SPT
Average job flow time 20.4 hours
Average hours early 3.6 hours
Average hours past due 7.6 hours
Average WIP 2.32 returns
Average total inventory 2.73 returns