Just-in-Time/Lean Production

1. Just-in-Time/Lean Production A repetitive production system in which the processing and movement of materials and goods occur just as they are needed!

2. Pre-JIT: Traditional Mass Production

3. Post-JIT: “Lean Production” Tighter coordination along the supply chain Goods are pulled along — only make and ship what is needed

4. JIT Goals(throughout the supply chain) • Eliminate disruptions • Make the system flexible • Reduce setup times and lead times • Minimize inventory • Eliminate waste

5. Waste Definition: Waste is ‘anything other than the minimum amount of equipment, materials, parts, space, and worker’s time, which are absolutely essential to add value to the product.’ — Shoichiro Toyoda President, Toyota

6. Forms of Waste: • Overproduction • Waiting time • Transportation • Processing • Inventory • Motion • Product Defects

7. Inventory as a Waste • Requires more storage space • Requires tracking and counting • Increases movement activity • Hides yield, scrap, and rework problems • Increases risk of loss from theft, damage, obsolescence

8. Building Blocks of JIT • Product design • Standard parts • Modular design • Quality • Process design • Personnel and organizational elements • Manufacturing planning and control

9. Process Design • “Focused Factories” • Group Technology • Simplified layouts with little storage space • Jidoka andPoka-Yoke • Minimum setups

10. Personnel and Organizational Elements • Workers as assets • Cross-trained workers • Greater responsibility at lower levels • Leaders as facilitators, not order givers

11. Classic Organizational View

12. JIT Organization View

13. Planning and Control Systems • “Small” JIT • Stable and level schedules • Mixed Model Scheduling • “Push” versus “Pull” • Kanban Systems

14. Kanban Uses simple visual signals to control production • Examples: • empty slot in hamburger chute • empty space on floor • kanban card

15. Kanban Example Workcenter B uses parts produced by Workcenter A How can we control the flow of materials so that B always has parts and A doesn’t overproduce?

16. Kanban card: Signal to produce When a container is opened by Workcenter B, its kanban card is removed and sent back to Workcenter A. This is a signal to Workcenter A to produce another box of parts.

17. Empty Box: Signal to pull Empty box sent back. Signal to pull another full box into Workcenter B. Question: How many kanban cards here? Why?

18. How Many Kanbans? y = number of kanban cards D = demand per unit of time T = lead time C = container capacity X = fudge factor

19. Example • Hourly demand = 300 units • Lead time = 3 hours • Each container holds 300 units • Assuming no variation in lead-time or demand (x = 0): y = (300  3) / 300 = 3 kanban cards

20. Extending the pull system

21. Note: • For a kanban system to work, we NEED CONSISTENT demand across the work centers • How do we ensure this?

22. Mixed Model Sequencing Largest integer that divides evenly into daily requirement is 10: A: 40 / 10 = 4 B: 40 / 10 = 4 C: 10 / 10 = 1 Mixed model sequence: A-B-A-B-A-B-A-B-C

23. Implementing JIT What about automation?

24. Putting the Squeeze on Resources