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JIT and Lean Operations

JIT and Lean Operations. JIT/Lean Production. 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   lean production JIT  pull (demand) system JIT operates with very little “fat”.

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JIT and Lean Operations

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  1. JIT andLean Operations

  2. JIT/Lean Production • 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  lean production • JIT  pull (demand) system • JIT operates with very little “fat”

  3. Goal of JIT The ultimate goal of JIT is a balanced system. Achieves a smooth, rapid flow of materials through the system

  4. Summary JIT Goals and Building Blocks Ultimate Goal A balanced rapid flow Supporting Goals Eliminate disruptions Eliminate waste Make the system flexible Building Blocks Product Design Process Design Personnel Elements Manufactur-ing Planning Figure 15.1

  5. Supporting Goals • Eliminate disruptions • Make system flexible • Eliminate waste, especially excess inventory

  6. Sources of Waste • Overproduction • Waiting time • Unnecessary transportation • Processing waste • Inefficient work methods • Product defects

  7. Kaizen Philosophy • Waste is the enemy • Improvement should be done gradually and continuously • Everyone should be involved • Built on a cheap strategy • Can be applied anywhere

  8. Kaizen Philosophy (cont’d) • Supported by a visual system • Focuses attention where value is created • Process orienteted • Stresses main effort of improvement should come from new thinking and work style • The essence of organizational learning is to learn while doing

  9. Big vs. Little JIT • Big JIT – broad focus • Vendor relations • Human relations • Technology management • Materials and inventory management • Little JIT – narrow focus • Scheduling materials • Scheduling services of production

  10. JIT Building Blocks • Product design • Process design • Personnel/organizationalelements • Manufacturing planning and control

  11. Product Design • Standard parts • Modular design • Highly capable production systems • Concurrentengineering

  12. Process Design • Small lot sizes • Setup time reduction • Manufacturing cells • Limited work in process • Quality improvement • Production flexibility • Balanced system • Little inventory storage

  13. Quality Improvement • Autonomation • Automatic detection of defects during production • Jidoka • Japanese term for autonomation

  14. Pull/Push Systems • Pull system: System for moving work where a workstation pulls output from the preceding station as needed. (e.g. Kanban) • Push system: System for moving work where output is pushed to the next station as it is completed

  15. 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” • Paperless production control system • Authority to pull, or produce comes from a downstream process.

  16. Kanban Formula DT(1+X) N = C N = Total number of containers D = Planned usage rate of using work center T = Average waiting time for replenishment of parts plus average production time for a container of parts X = Policy variable set by management - possible inefficiency in the system C = Capacity of a standard container

  17. Limited Work in Process • Benefits • Lower carrying costs • Increased flexibility • Aids scheduling • Saves cost of rework and scrap • Two general approaches • Kanban – focuses on individual work stations • Constant work in process (CONWIP) – focuses on the system as a whole

  18. Buyer Supplier Supplier Supplier Supplier Supplier Supplier Supplier Traditional Supplier Network Figure 15.4a

  19. Tiered Supplier Network Buyer Supplier Supplier Supplier Supplier Supplier Supplier Supplier Figure 15.4b First Tier Supplier Second Tier Supplier Third Tier Supplier

  20. Preventive Maintenance andHousekeeping • Preventative maintenance: Maintaining equipment in good condition and replacing parts that have a tendency to fail before they actually fail. • Housekeeping: Maintaining a workplace that is clean and free of unnecessary materials.

  21. Housekeeping Five S’s • Sort • Straighten • Sweep • Standardize • Self-discipline

  22. Comparison of JIT and Traditional Table 15.3

  23. Transitioning 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

  24. Obstacles to Conversion • Management may not be committed • Workers/management may not be cooperative • Difficult to change company culture • Suppliers may resist • Why?

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