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Chapter 11

Chapter 11. Just-In-Time and Lean Production. To Accompany Russell and Taylor, Operations Management, 4th Edition ,  2003 Prentice-Hall, Inc. All rights reserved. What is JIT ?. Producing only what is needed, when it is needed A philosophy An integrated management system

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Chapter 11

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  1. Chapter 11 Just-In-Time and Lean Production To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved.

  2. What is JIT ? • Producing only what is needed, when it is needed • A philosophy • An integrated management system • JIT’s mandate: Eliminate all waste

  3. Basic Elements of JIT Flexible resources Cellular layouts Pull production system Kanban production control Small-lot production Quick setups Uniform production levels Quality at the source Total productive maintenance Supplier networks

  4. Waste in Operations Figure 11.1

  5. Waste in Operations Figure 11.1

  6. Waste in Operations Figure 11.1

  7. Flexible Resources • Multifunctional workers • General purpose machines • Study operators & improve operations

  8. Worker: Russell Cycle Time: 2 min Standard Operating Routine Sheet 1 Order of Operations time Operations :10 :20 :30 :40 :50 1:00 1:10 1:20 1:30 1:40 1:50 2:00 Pick up material Unload/ load machine 1 Unload/ load machine 2 Unload/ load machine 3 Inspect/ pack Standard Operating Routine for a Worker Figure 11.2

  9. Cellular Layouts • Group dissimilar machines in manufacturing cell to produce family of parts • Work flows in one direction through cell • Cycle time adjusted by changing worker paths

  10. Cell 1 Worker 1 Worker 2 Worker 3 Manufacturing Cell with Worker Routes Figure 11.3

  11. Cell 1 Cell 2 Worker 2 Worker 1 Worker 3 Cell 3 Cell 4 Cell 5 Worker Routes Lengthened as Volume Decreases Figure 11.4

  12. The Pull System • Material is pulled through the system when needed • Reversal of traditional push system where material is pushed according to a schedule • Forces cooperation • Prevent over and underproduction

  13. Kanban Production Control System • Kanban card indicates standard quantity of production • Derived from two-bin inventory system • Kanban maintains discipline of pull production • Production kanban authorizes production • Withdrawal kanban authorizes movement of goods

  14. A Sample Kanban

  15. a) Two-bin inventory system b) Kanban inventory system Bin 1 Kanban Bin 2 Reorder card Q - R R R Q = order quantity R = reorder point - demand during lead time The Origin of Kanban Figure 11.5

  16. Types of Kanbans Figure 11.6

  17. Types of Kanbans Figure 11.6

  18. Types of Kanbans Figure 11.6

  19. Types of Kanbans • Kanban Square • Marked area designed to hold items • Signal Kanban • Triangular kanban used to signal production at the previous workstation • Material Kanban • Used to order material in advance of a process • Supplier Kanbans • Rotate between the factory and suppliers

  20. average demand during lead time + safety stock container size No. of Kanbans = dL + S C N = Determining Number of Kanbans where N = number of kanbans or containers d = average demand over some time period L = lead time to replenish an order S = safety stock C = container size

  21. 75 + 7.5 25 dL + S C (150 x 0.5) + 7.5 25 N = = = = 3.3 kanbans or containers Determining the Number of Kanbans d = 150 bottles per hour L = 30 minutes = 0.5 hours S = 0.10(150 x 0.5) = 7.5 C = 25 bottles Round up to 4 (to allow some slack) or down to 3 (to force improvement) Example 11.1

  22. Small-Lot Production • Requires less space & capital investment • Moves processes closer together • Makes quality problems easier to detect • Makes processes more dependent on each other

  23. Inventory Hides Problems

  24. Lower Levels of Inventory Expose Problems

  25. Components of Lead Time • Processing time • Reduce number of items or improve efficiency • Move time • Reduce distances, simplify movements, standardizeroutings • Waiting time • Better scheduling, sufficient capacity • Setup time • Generally the biggest bottleneck

  26. SMED Principles Separate internal setup from external setup Convert internal setup to external setup Streamline all aspects of setup Perform setup activities in parallel or eliminate them entirely

  27. Common Techniques for Reducing Setup Time Figure 11.8

  28. Common Techniques for Reducing Setup Time Figure 11.8

  29. Common Techniques for Reducing Setup Time Figure 11.8

  30. Uniform Production • Results from smoothing production requirements • Kanban systems can handle +/- 10% demand changes • Smooths demand across planning horizon • Mixed-model assembly steadies component production

  31. Mixed-Model Sequencing Example 11.2

  32. Quality at the Source • Jidoka is authority to stop production line • Andon lights signal quality problems • Undercapacity scheduling allows for planning, problem solving & maintenance • Visual control makes problems visible • Poka-yoke prevents defects

  33. Visual Control Figure 11.9

  34. Visual Control Figure 11.9

  35. Visual Control Figure 11.9

  36. Kaizen • Continuous improvement • Requires total employment involvement • Essence of JIT is willingness of workers to • Spot quality problems • Halt production when necessary • Generate ideas for improvement • Analyze problems • Perform different functions

  37. Total Productive Maintenance (TPM) • Breakdown maintenance • Repairs to make failed machine operational • Preventive maintenance • System of periodic inspection & maintenance to keep machines operating • TPM combines preventive maintenance & total quality concepts

  38. TPM Requires Management to: • Design products that can be easily produced on existing machines • Design machines for easier operation, changeover, maintenance • Train & retrain workers to operate machines • Purchase machines that maximize productive potential • Design preventive maintenance plan spanning life of machine

  39. Supplier Policies Locate near to the customer Use small, side loaded trucks and ship mixed loads Consider establishing small warehouses near to the customer or consolidating warehouses with other suppliers Use standardized containers and make deliveries according to a precise delivery schedule Become a certified supplier and accept payment at regular intervals rather than upon delivery

  40. Benefits of JIT Reduced inventory Improved quality Lower costs Reduced space requirements Shorter lead time Increased productivity Greater flexibility Better relations with suppliers Simplified scheduling and control activities Increased capacity Better use of human resources More product variety

  41. JIT Implementation • Use JIT to finely tune an operating system • Somewhat different in USA than Japan • JIT is still evolving • JIT isn’t for everyone

  42. JIT In Services • Competition on speed & quality • Multifunctional department store workers • Work cells at fast-food restaurants • Just-in-time publishing for textbooks • Construction firms receiving material just as needed

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