Jit systems

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Jit systems

  1. 1. JIT SYSTEMS
  2. 2. <ul><li>Japanese industry works JUST IN TIME </li></ul><ul><li>Others work JUST IN CASE </li></ul>STOCKLESS PRODUCTION ? JIT System is the organisation of resources, information flows and decision rules that can enable an organisation to realise the benefits of JIT philosophy
  3. 3. Push & Pull <ul><li>When to use? </li></ul><ul><li>Is JIT applicable in all manufacturing environments ? </li></ul>Highly repetitive Well defined Material Flows Deterministic Pull Systems : Is it Made to order? Is there a delay at Customer delivery end?
  4. 4. MURI MURA MUDA EXCESS WASTE UNEVENNESS X X X From Overproduction Waiting Time Transportation Inventory Processing Waste Waste of motion Product defects
  5. 5. Characteristics <ul><li>Consistently High quality : Low rework </li></ul><ul><li>How to achieve ? </li></ul><ul><li>andon systems? </li></ul>
  6. 6. (SINS) OF MANUFACTURING <ul><li>EOQ ? </li></ul><ul><li>SET UP TIME ? </li></ul><ul><li>ECONOMIES OF SCALE ? </li></ul><ul><li>SQC? </li></ul><ul><li>THE SECURITY BLANKET? </li></ul>
  7. 7. Setup, Capacity and JIT <ul><li>JIT has low leadtime (MLT) </li></ul><ul><li>Higher capacity can reduce MLT? </li></ul><ul><ul><li>Example : </li></ul></ul><ul><ul><ul><li>Arrival rate of products : 15/hour </li></ul></ul></ul><ul><ul><ul><li>Service rate : 16 /hour </li></ul></ul></ul><ul><ul><ul><li>Lead time ? </li></ul></ul></ul>
  8. 8. Setup, Capacity and JIT <ul><li>JIT has low leadtime (MLT) </li></ul><ul><li>Higher capacity can reduce MLT? </li></ul><ul><ul><li>Example : </li></ul></ul><ul><ul><ul><li>Arrival rate of products : 15/hour </li></ul></ul></ul><ul><ul><ul><li>Service rate : 15.1 /hour </li></ul></ul></ul><ul><ul><ul><li>Lead time = 1/(mu-lambda) = 1/0.1 = 10 hours </li></ul></ul></ul><ul><ul><ul><li>If service rate changes by 1.3% </li></ul></ul></ul><ul><ul><ul><li>Lead time reduces to 3.33 hours </li></ul></ul></ul><ul><ul><ul><li>A small increase in production rate A LARGE SAVING IN MLT </li></ul></ul></ul><ul><ul><ul><li>What about inventory? </li></ul></ul></ul>
  9. 9. Setup, Capacity and JIT <ul><li>Finding the inventory reduction? </li></ul><ul><ul><li>Example : </li></ul></ul><ul><ul><ul><li>Arrival rate of products : 15/hour </li></ul></ul></ul><ul><ul><ul><li>Service rate : 15.1 /hour </li></ul></ul></ul><ul><ul><ul><li>WIP (no.of units in system) = lambda/(mu-lambda) = 15/0.1 = 150 units </li></ul></ul></ul><ul><ul><ul><li>If service rate changes by 1.3% </li></ul></ul></ul><ul><ul><ul><li>WIP reduces to 15/0.3 i.e. 50 units </li></ul></ul></ul><ul><ul><ul><li>A small increase in production rate A LARGE SAVING IN Inventory </li></ul></ul></ul><ul><ul><li>HOW TO ACHIEVE? </li></ul></ul><ul><ul><ul><li>Set up </li></ul></ul></ul><ul><ul><ul><li>Capacity </li></ul></ul></ul>
  10. 10. (SINS) OF JIT ? <ul><li>A GLORIFIED INVENTORY MGMT? </li></ul><ul><li>EXPENSIVE </li></ul><ul><li>WHY SHOULD SUPPLIER CARRY THE BURDEN? </li></ul><ul><li>JIT NEEDS HARDWORK... WHY SHOULD I DO IT? </li></ul>
  11. 11. SNOW BALL EFFECT jit Reduced stock quality Overhead costs Setup time scrap problems Feedback Cost Savings Even Production Process
  12. 12. Characteristics <ul><li>Pull System for Material Flow </li></ul><ul><li>Consistently High Quality </li></ul><ul><ul><li>Control of quality at source </li></ul></ul><ul><ul><li>Use of SQC techniques </li></ul></ul><ul><li>Lot Sizes </li></ul><ul><ul><li>WIP inventory </li></ul></ul><ul><ul><li>Uniform load at workstations </li></ul></ul><ul><ul><li>Single digit setup </li></ul></ul>
  13. 13. Characteristics: Consistent Quality <ul><li>Can you reduce defect rate by increasing lot size? </li></ul><ul><li>Small Lot size? </li></ul>Reduce cycle inventory Reduce lead times - why? Uniform operating system load But what about setup time?
  14. 14. Characteristics <ul><li>Uniform workstation load </li></ul><ul><ul><li>Mixed model assembly (Heijunka) </li></ul></ul><ul><li>Standardized components and work methods </li></ul><ul><ul><li>The learning curve of repeated tasks </li></ul></ul><ul><li>supplier ties </li></ul><ul><ul><li>Lean base, short lead time, VMI </li></ul></ul><ul><ul><li>Local base </li></ul></ul><ul><ul><li>“ Complete Tear down” philosophy </li></ul></ul>
  15. 15. Characteristics <ul><li>Flexible work force </li></ul><ul><ul><li>Team Approach in Volvo </li></ul></ul><ul><li>Line flow Strategy : </li></ul><ul><ul><li>GT Layout </li></ul></ul><ul><ul><li>One Worker Multiple Machines </li></ul></ul><ul><li>Automated Production - always ? </li></ul><ul><li>Preventive and Productive Maintenance </li></ul>

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