Chapter 13 Lean Systems

1. Chapter 13 Lean Systems

2. Characteristics of Lean Systems: Just-in-Time • Pull method of materials flow • Consistently high quality • Small lot sizes • Uniform workstation loads • Standardized components and work methods • Close supplier ties • Flexible workforce • Line flows • Automated production • Preventive maintenance

3. 100 – 75 – 50 – 25 – 0 – Average cycle inventory Lot size = 100 On-hand inventory Lot size = 50 5 10 15 20 25 30 Time (hours) Figure 13.1 Lot Size and Cycle Inventory

4. 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

5. Inventory Hides Problems

6. Unreliable suppliers Capacity imbalance Scrap Continuous Improvement with Lean Systems Figure 13.2

7. 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

8. 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

9. Common Techniques for Reducing Setup Time Figure 11.8

10. Common Techniques for Reducing Setup Time Figure 11.8

11. Common Techniques for Reducing Setup Time Figure 11.8

12. 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

13. Mixed-Model Sequencing Example 11.2

14. Quality at the Source • Jidokais 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

15. 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

16. 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

17. 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

18. 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

19. Consistently high quality • Uniform facility loads • Standardized work methods • Close supplier ties • Flexible workforce • Automation • Preventive maintenance • Pull method of materials flow • Line flows Lean Systems in Services

20. Reduce space requirements • Reduce inventory investment • Reduce lead times • Increase labor productivity • Increase equipment utilization • Reduce paperwork and simple planning systems • Valid priorities for scheduling • Workforce participation • Increase product quality Operational Benefits

21. Implementation Issues • Organizational considerations • Human cost of JIT systems • Cooperation and trust • Reward systems and labor classifications • Process considerations • Inventory and scheduling • MPS stability • Setups • Purchasing and logistics