Just-in-Time System. Dr S G Deshmukh

Transcription

1 Just-in-Time System Dr S G Deshmukh

2 Difficulty in Production! Demand is uncertain and variable. Same equipment and people are used to make a variety of products. Switching products takes time.(imagaine changing over from say dark shade to light shade in a paint manufacturing!) Things may go wrong(murphy s law!) Materials are defective. Deliveries are variable (late). Equipment fails, people make mistakes, etc. And so many other reasons..

3 Solution 1: Use Inventory Use inventory to: Match supply with varying demand. Act as a buffer Allow production of a variety of products on the same equipment, tools etc. Overcome defective materials, late deliveries, equipment failures, mistakes, etc.

4 Typical Production Forecast demand based on classical methods Produce in large lots (to reduce expensive setups) & economics of scale PUSH product to customer.(even if he/she doesn't want!) Large lot sizes mean: Large work-in-process inventories. Large final product inventories. Slow response to changes and defects. Opaque view of the ground!

5 Solution 2: Use Just-In-Time Use just-in-time to identify and solve problems that create inventory. Reduce setup costs to switch products. Expose yourself to problems rather than hiding under the cover of inventory! Eliminate defective materials, late deliveries, equipment failures, mistakes, etc.

6 Just-in-Time Production Produce in small lots to replenish stock actually sold. Sales PULL product (and parts) through plant. Get pulse of the market! Small lot sizes mean: Small work-in-process inventories. Small final product inventories. Quick response to changes and defects.

7 What is Waste? Waste is anything other than the minimum amount of equipment, materials, parts, space, and worker s time, which are absolutely essential to add value to the product. Shoichiro Toyoda President, Toyota

8 Different Kinds of Waste Waste from Over-production Waste of Motion Transportation waste Processing waste Defective Products Excess Inventory Information waste Energy waste Manpower waste

9 Elimination of Waste JIT attempts to eliminate all costs (waste) that DO NOT ADD any value to a product. Machining, Packaging, Assembling etc. add value to a product BUT Moving, Storing, Counting, Sorting etc add COST but No Value to a product. Hence try to eliminate them.

10 What is Just-in-Time? Management philosophy of continuous and forced problem solving. Supplies and components are pulled through system to arrive where they are needed when they are needed. Originated in Japan; Popularized by Toyota; now used globally.

11 Steps to Reduce Setup Time Separate setup into preparation (while machine is running) and actual setup (while machine is stopped). Do as much as possible while the machine is running. Move material closer and improve material handling. Standardize and improve tooling.

12 Comment INVENTORY is an Undesirable cost. By LOWERING it, Hidden quality and Production impediments are revealed. Simplification and Elimination through Problem Solving, continuous improvement is the key.

13 JIT 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

14 American Production and Inventory Control Society (APICS) definition of JIT "a philosophy of manufacturing based on planned elimination of all waste and continuous improvement of productivity. encompasses successful execution of all manufacturing activities required to produce final product, from design engineering to delivery and including all stages of conversion from raw material onward.

15 Goals of JIT A manufacturing process that is so streamlined, cost efficient, quality oriented and responsive to customer, that it becomes a strategic weapon. The goals in most cases consists of : Produce product only on demand. Produce a perfect quality product. Reduce the cost of manufacturing. Integrate and to optimize every step of manufacturing process. Develop manufacturing Flexibility Keep commitments made to customers and suppliers

16 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

17 JIT Through Product design Process design Personnel/organizational elements Manufacturing planning and control

18 Enabler : Product Design Standard parts Modular design Highly capable production systems Concurrent engineering Use of CAD/CAM Use of CFD

19 Enabler.. Process Design Small lot sizes Setup time reduction Manufacturing cells Limited work in process Quality improvement Production flexibility Little inventory storage

20 Production Flexibility Reduce downtime by reducing changeover time Multi-tools, workstations Use preventive maintenance to reduce breakdowns Cross-train workers to help clear bottlenecks Use many small units of capacity Use off-line buffers Reserve capacity for important customers

21 Enabler : Personnel/Organizational Elements Workers as assets Cross-trained workers Belief in improvement by workers Continuous improvement Cost accounting Organic element of human being!! Leadership/project management

22 Enabler.. Planning & Control Level loading Pull systems Visual systems (Andon, alarms etc.) Close vendor relationships Reduced transaction processing Preventive maintenance

23 Models for supplier Arms Length Model Closed, Competitive Evaluation on lowest bid Data/Information sharing very limited Inspection based quality regime No shared R&D Partnership Model Collaboration based Multi-criteria evaluation of sources Sharing of data/information encouraged Participative attitude towards quality Shared R&D

24 Buyer Supplier Relationship Buyer Action Attributes Supplier Action Attributes Joint Action Attributes Outcome Attributes

25 Buyer Action Fewer suppliers Long term contract Increased volume to suppliers Supplier evaluation/certification Training and audit Freight consolidation Stable production schedule Performance evaluation

26 Supplier Action.. SPC Close proximity Quality circle Flexible suppliers Reduced set ups Increased customer support

27 Joint Action Mutual trust & cooperation Information sharing Joint design & development Continuous improvement

28 Outcome Frequent & reliable deliveries Small shipment Reduced paperwork Shared perceptions Flexibility in everything!

29 Benefits Cooperation, reduced inventory, quality at low cost, better planning and control, less paperwork improved communication

30 Kanban as a 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.

31 Kanban.. fixed quantity bins or containers or pallets used to signal replenishment needs (reminiscent of traditional two-bin system of stock control). When first bin empty, new full bin moved in within usage time from the second bin). With well-designed floor layouts, system adds considerably to efficiency of operational environment. integration of computer systems internally & externally with suppliers systems so Kanban data & instructions can flow between linked systems.

32 Youtube on JIT (10.56 minutes) FKBf1rOyo

33 Frank Sinatra sings JIT (2.18 minutes) Q26arWAs

34 NPTEL session By Prof G Srinivasan (IIT Madras) on JIT (51 minutes) 7zCjLjyw

35 Suppliers JIT objective: Frequent on-time deliveries of small lots of high quality. Buyer and supplier form JIT partnerships to eliminate: Unnecessary activities. In-plant inventory. In-transit inventory. Poor suppliers.

36 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

37 Barriers to migration Management may not be committed Workers/management may not be cooperative Suppliers may resist Why?

38 Benefits of JIT Systems Reduced inventory levels High quality Flexibility Reduced lead times Increased productivity

39 Benefits of JIT Systems..cont d Increased equipment utilization Reduced scrap and rework Reduced space requirements Pressure for good vendor relationships Reduced need for indirect labor

40 Benefits of JIT.. Contd. Part Cost: Low scrap, Low Inventory Quality: Fast detection, Corrections Design: Fast Response to Engineering changes Administration Efficiency: Fewer suppliers, minimal expediting, less paper work Productivity: Reduced rework/inspection delay, reduced parts

41 Quality JIT exposes quality problems by reducing inventory. JIT limits number of defects produced with small lots. JIT requires TQM. Statistical process control. Worker involvement & empowerment. Immediate feedback.

42 JIT is flow JIT Is Flow is Hirano and Furuya s book which gives an extensive practical overview of JIT/Lean. Jit-Is-Flow-Hiroyuki- Hirano/dp/

43 Interesting book.. om/en-us/ebook/toyotasupply-chainmanagement-a-strategicapproach-to-toyota-srenowned-system

44 Toyota Global.. toyota_production_system/just-intime.html

45 Summary JIT as a philosophy Attack on elimination of waste Pull based system Critical Factors Involvement of top management Simplified processes Orientation towards inventory