5a session 5a_jit systems cfvg 2012
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Dr. Ravi Shankar presents information on just-in-time (JIT) systems in operations management. JIT originated in Japan as the Toyota Production System and focuses on eliminating waste to improve production. Key aspects of JIT include a pull system of production, small lot sizes, quality control, continuous improvement, and minimizing inventory levels to reduce problems. JIT requires strong partnerships with suppliers for fast, regular deliveries in small lots. The goals of JIT are to lower costs, improve quality and responsiveness through streamlined, waste-free production.
5a session 5a_jit systems cfvg 2012
- 1. Dr. RAVI SHANKAR Professor Department of Management Studies Indian Institute of Technology Delhi Hauz Khas, New Delhi 110 016, India Phone: +91-11-26596421 (O); 2659-1991(H); (0)-+91-9811033937 (m) Fax: (+91)-(11) 26862620 Email: r.s.research@gmail.com http://web.iitd.ac.in/~ravi1 SESSION#5a: Just-in-Time Systems (CFVG: 2012) JUST IN TIME SYSTEMS IN OPERATIONS MANAGEMENT
- 2. The philosophy of JIT can be traced back to Henry Ford, but formalized JIT originated in Japan as the Toyota Production System. W. Edwards Deming’s lesson of variability reduction was a huge influence. The focus of JIT is to improve the system of production by eliminating all forms of WASTE. Just-In-Time Philosophy JIT is a long-term approach to process improvement. It uses timeliness as a lever to lower costs, improve quality and improve responsiveness. However, JIT requires enormous commitment. It took Toyota more than 25 years to get right!
- 3. The Seven Zeros: To identify waste • Zero Defects: Quality at the source • Zero Lot Size: To avoid batching delays • Zero Setups: To minimize setup delay and allow production in small lots • Zero Breakdowns: To avoid stopping tightly coupled line • Zero Handling: To promote flow of parts • Zero Lead Time: To ensure rapid replenishment of parts • Zero Surging: Necessary in system without WIP buffers. Waste exists unless all the following goals are achieved
- 4. 4 Lean Production Lean Production can be defined as an integrated set of activities designed to achieve high-volume production using minimal inventories (raw materials, work in process, and finished goods) Lean Production also involves the elimination of waste in production effort Lean Production also involves the timing of production resources (i.e., parts arrive at the next workstation “just in time”)
- 5. 4/10/20125 (c) Dr. Ravi Shankar, AIT (2008) 5 Just-in-Time (JIT) Mfg. Producing just what is needed, when it is needed, in the amount needed, with only the minimum required materials, equipment, labor, and space.
- 6. 6 Pull System Customers Sub Sub Fab Fab Fab Fab Vendor Vendor Vendor Vendor Final Assembly Here the customer starts the process, pulling an inventory item from Final Assembly… Here the customer starts the process, pulling an inventory item from Final Assembly… Then sub- assembly work is pulled forward by that demand… Then sub- assembly work is pulled forward by that demand… The process continues throughout the entire production process and supply chain The process continues throughout the entire production process and supply chain
- 7. 7 Features of Lean Production • Management philosophy • “Pull” system though the plant WHAT IT IS • Employee participation • Industrial engineering/basics • Continuing improvement • Total quality control • Small lot sizes WHAT IT REQUIRES • Attacks waste • Exposes problems and bottlenecks • Achieves streamlined production WHAT IT DOES • Stable environment WHAT IT ASSUMES
- 8. 8 The Toyota Production System (TPS) Based on two philosophies: • 1. Elimination of waste • 2. Respect for people
- 9. 9 Some Examples of Waste • Watching a machine run • Waiting for parts • Counting parts • Over-runs in production • Moving parts over long distances • Storing inventory • Looking for tools • Machine breakdown • Rework
- 10. 10 Toyota Production System’s Four Rules 1. All work shall be highly specified as to content, sequence, timing, and outcome 2. Every customer-supplier connection must be direct, and there must be an unambiguous yes-or-no way to send requests and receive responses 3. The pathway for every product and service must be simple and direct 4. Any improvement must be made in accordance with the scientific method, under the guidance of a teacher, at the lowest possible level in the organization
- 11. 11 How Basic Elements of JIT Contribute to the “system” Pull (Kanban) production control system • Produce only what is needed - only when it is needed Small-lot production • Faster through-put, greater flexibility Quick setups • Facilitates economical small-lot-size production Flexible resources • Facilitates cellular layouts, TPM, and Kaizen Cellular layouts • Retain relevant flexibility of job shop, obtain efficiency of production line
- 12. 12 How Basic Elements of JIT Contribute to the “system” Uniform production • Create and maintain a stable production system Quality at the source • Facilitates removal of “buffers” and contributes to stability of the “system” Total productive maintenance • Contributes to stability of the “system” Supplier networks • Facilitates frequent, small quantity delivery of materials
- 13. 13 Minimizing Waste: Inventory Hides Problems Work in process queues (banks) Change orders Engineering design redundancies Vendor delinquencies Scrap Design backlogs Machine downtime Decision backlogs Inspection backlogs Paperwork backlog Example: By identifying defective items from a vendor early in the production process the downstream work is saved Example: By identifying defective work by employees upstream, the downstream work is saved
- 15. 15 To Expose Problems: Reduce Inventory Levels Poor Quality Unreliable Supplier Machine Breakdown Inefficient Layout Bad Design Lengthy Setups
- 16. 16 Remove Sources of Problems and Repeat the Process Poor Quality Unreliable Supplier Machine Breakdown Inefficient Layout Bad Design Lengthy Setups
- 17. 17 JIT Production: Total Quality Control Worker responsibility Measure SQC Enforce compliance Fail-safe methods Automatic inspection ....
- 18. 18 Quality At The Source Jidoka is authority to stop production line Andon lights signal quality problems Under-capacity scheduling allows for planning, problem solving & maintenance Visual signals for production control makes problems apparent to everyone Poka-yoke (mistake-proofing) prevents defects
- 19. 19 Kaizen Continuous improvement Requires total employee 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
- 20. 20 JIT Production: Work with Vendors Reduce lead times Frequent deliveries Project usage requirements Quality expectations ....
- 21. 21 JIT Production: Minimize Setup Times What are the consequences of long setup times? A requirement for small-lot-size, mixed-model production? ....
- 22. 4/10/201222 (c) Dr. Ravi Shankar, AIT (2008) 22 JIT Production? Pull Systems? Kanban? … How does it all relate? “Kanban” • Means “card” in Japanese • It is a “pull” production system and used as the means of production control in JIT How kanbans work: • When an order to produce a finished product is issued to the plant, workers withdraw components from a “standard container” and build the product. • Each container has a kanban on it, which is sent to the upstream as an authorization to produce. • This in turn activates kanbans at that operation, sent to the next operation upstream, and so on. The process goes all the way to kanbans issued to the vendor to produce and/or ship. • Computer control is unnecessary:
- 23. 23 Minimizing Waste: Kanban Production Control Systems Storage Part A Storage Part AMachine Center Assembly Line Material Flow Card (signal) Flow Withdrawal kanban Once the Production kanban is received, the Machine Center produces a unit to replace the one taken by the Assembly Line people in the first place This puts the system back were it was before the item was pulled The process begins by the Assembly Line people pulling Part A from Storage Production kanban
- 24. 24 Kanban Card 46-281247p1 27” Al Rim Qty 23 Stock Loc: RIP 1 Line Loc: Asm. 1 Unique Part # Description Kanban Qty Where to find part when bin is empty Where to return filled Kanban
- 25. 4/10/201225 (c) Dr. Ravi Shankar, AIT (2008) 25 Characteristics of Systems Well-suited to JIT Discrete parts produced in a highly repetitive environment. Fairly smooth demand pattern throughout the year. Setup times/costs that can be reduced. High worker flexibility - solve problems Close proximity to vendors.
- 26. 4/10/201226 (c) Dr. Ravi Shankar, AIT (2008) 26 JIT Philosophy Requires Strong Partnerships with Suppliers Characteristics of true JIT buyer-supplier partnerships • JIT requires fast and regular supply • Cost not only factor in vendor selection: quality, flexibility and delivery are also key factors. • Preferred vendors offer small lot sizes, frequent deliveries • JIT requires few to single suppliers to solidify partnerships Typical Supplier Concerns • Erratic schedules from customer • Impact of small lot sizes - additional transportation costs. • Proximity
- 27. 4/10/201227 (c) Dr. Ravi Shankar, AIT (2008) 27 CONCLUSION
- 28. The Lessons of JIT •The production environment itself is a control •Operational details matter strategically •Controlling WIP is important •Speed and flexibility are important assets •Quality can come first •Continual improvement is a condition for survival
- 29. 29 Just-In-Time Production • Management philosophy • Pull system though the plant • Management philosophy • Pull system though the plant WHAT IT IS • Employee participation • Industrial engineering/basics • Continuing improvement • Total quality control • Small lot sizes • Employee participation • Industrial engineering/basics • Continuing improvement • Total quality control • Small lot sizes WHAT IT REQUIRES • Attacks waste (time, inventory, scrap) • Exposes problems and bottlenecks • Achieves streamlined production • Attacks waste (time, inventory, scrap) • Exposes problems and bottlenecks • Achieves streamlined production WHAT IT DOES • Stable environment• Stable environment WHAT IT ASSUMES ....