Agenda. The first battle. Japanese manufacturing strategies. TPPE37 Manufacturing Control

Transcription

1 TPPE37 Manufacturing Control Agenda Lecture 8 JIT and lean production JIT-philosophy Techniques to support JIT Kanban control A case study in GE Ou Tang 1 Ou Tang 2 The first battle Japanese manufacturing strategies In In H-D H-D tried tried to to prove in in court court that that their their Japanese competitors were were dumping their their products on on the the american market. Invest. showed that the the Jap. compet. costs were 30% lower Action: In In H-D H-Dcopied the the three three most most common approaches the the Japanese manufacturers employed in intheir cost cost efficient manufact. Quality Quality circles circles Statistical process processcontrol control Kanban Kanban controlled manufacturing Results: Reduced inventories by by 40% 40% Increased productivity (MC (MC per peremployee) of of129% 30% 30% fewer suppliers Ou Tang 3 Aims at at simplicity Objective: To To eliminate waste Productivity, formalised as as Just in intime (JIT). Quality, continuous improvement(kaizen), formalised as as Total Quality Control (TQC). Ou Tang 4

2 JIT and Lean Management Minimizing Waste: Just-In-Time Production JIT can be divided into two terms: Big JIT and Little JIT Big JIT (also called Lean Management) is a philosophy of operations management that seeks to eliminate waste in all aspects of a firm s production activities Little JIT focuses more narrowly on scheduling goods inventory and providing service resources where and when needed WHAT IT IS Management philosophy Pull system though the plant WHAT IT REQUIRES Employee participation Industrial engineering/basics Continuing improvement Total quality control Small lot sizes WHAT IT DOES Attacks waste Exposes problems and bottlenecks Achieves streamlined production WHAT IT ASSUMES Stable environment Ou Tang 5 Ou Tang 6 Waste in Operations Minimizing Waste: Focused Factory Networks 1. Waste from overproduction 2. Waste of waiting time 3. Transportation waste 4. Inventory waste 5. Processing waste 6. Waste of motion 7. Waste from product defects Coordination System Integration These are are small specialized plants that that limit limit the the range of of products produced (sometimes only only one one type type of of product for for an an entire facility) Some plants in in Japan have have as as few few as as and and as as many as as employees Ou Tang 7 Ou Tang 8

3 Minimizing Waste: Group Technology (Part 1) Minimizing Waste: Group Technology (Part 2) Using Using Departmental Specialization for for plant plant layout layout can can cause cause a lot lot of of unnecessary material movement Revising by by using using Group Group Technology Cells Cellscan reduce reduce movement and and improve improve product product flow flow Saw Saw Saw Grinder Grinder Saw Grinder 1 2 Press Heat Treat Heat Treat Press Press Press Saw Grinder A B Press Note how the flow lines are going back and forth Ou Tang 10 Ou Tang 9 Minimizing Waste: Uniform Plant Loading (heijunka) Minimizing Waste: Inventory Hides Problems We operate a production plant. The schedule of production could be accomplished using one of the schedules below. Not uniform Jan. Units Feb. Units Mar. Units Total 1,200 3,500 4,300 9,000 or Uniform Jan. Units Feb. Units Mar. Units Total 3,000 3,000 3,000 9,000 How does the the uniform loading help save labor costs? Ou Tang 11 Work in process queues (banks) Paperwork backlog Scrap Machine downtime Vendor delinquencies Engineering design redundancies Inspection backlogs Change orders Design backlogs Decision backlogs 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 Ou Tang 12

4 The just-in-time approach Techiques in JIT Techniques for designing and planning the JIT manufacturing system JIT philosophical approach to manufacturing Techniques for control of the shop floor in a JIT system JIT approach: zero defects zero set-up time zero inventories zero breakdowns zero lead time lot size of one Smooth production Setup time reduction SMED Automation Poka-Yoke Flow group U-line Continuoue improving Kaizen Material requirements Kanban Ou Tang 13 Ou Tang 14 Smoothing production Production smoothing To utilise the resource more effectively To elimitate unblance and create a synchronised and balance productin flow. Improving areas: Master production shedule and final assembly schedule Phase 1: 1: Production smoothing adapting to to monthly demand changes. Satblise master schedule Phase 2: 2: Production smoothing adapting to to daily production dispatch Mixed-model assembly Ou Tang 15 Ou Tang 16

5 Smoothing production Mixed model assembly Traditional: 3 separate lines Component 1 D = (2,3,5) 1 line with setups Component 2 Component 3 Final assembly (FP1, FP2, FP3) JIT/TQC: 1 line with smooth production without setups Component 4 Ou Tang 17 Ou Tang 18 Mixed model assembly Setup time reduction - SMED Requirement of component 3 Komponent 3 Ideal β j min DK, i= K N, +, i 1 j= 1 Q X b K ( jk i j) SMED - Single Minute Exchange of of Die Setup time is is shoter than 10 10minutes Three steps to to achieve SMED Planning distinguish external and internal setup times Investment fixture, jiggar Education more operater, new technology Ou Tang 19 Ou Tang 20

6 Single Dandori approach in Mitsubishi Reducing setup time a case study Setup time Let s break it down into... Preset clean up Actual setup preparation Downtime Use your imagination Preset push outward work together Actual setup Preset A. setup <10 min. Fixtures Welded part Operator Robot Revolving fixture table Material, blanks Work station with welding operation Three product variants Processing time 50 seconds Setup time 1 hour EOQ corresponds to 13, 13, 22 days of production The aim is to reduce EOQ to two days of production Then the target setup time should be one minutes Let s reduce the downtime to less than 10 min.! Ou Tang 21 Ou Tang 22 Reducing setup time a case study Reducing setup time increasing profit Minimise load Short lead time Minimise safety stock Setup time reduction Minimise lot size Minimise cycle stock Increase production More production units per time unit Less WIP Less raw mtrl inven. Less finished Goods inven. Increase service level Low cost - inventory holding - material handling - warehouse space Low capital tiedup - raw mtrl inventory -WIP - finished goods High revenue - increase sales Ou Tang 23 Increasing profit Ou Tang Profit= (revenue-cost)/capital 24

7 Autonomation Poka-Yoke U-Shap machine layout Automation with a human touch Poka-Yoke is is a system which automatically stops the machine if if there is: Process defect Product defect Over production Production is is organisered in in group (cellular manufacturing). Each cellular is is organisered in in U-shpe layout inorder to: Minimise material hadeling Use operater s multitask ability (in (in combination with Poka-Yoke). Blance the the production Ou Tang 25 Ou Tang 26 Continuous improveing - Kaizen Kanban Measurement External and Internal Analysis Analyze Variation Control Adjust Process Improvement Reduce Variation Innovation Redesign Product/Process PDCA = Plan, Do, Check, Act Ou Tang 27 P C D A Control Improve P C D A Innovate Improve Simple ordering system Decentralised, automatic Almost paperless Circulating cards (Kanbans) Production Kanban Transport Kanban Standardised containers Demand pull Demand creates requirement for for replenishment Run order According to to the the card card sequence Ou Tang 28

8 Kanban Production Control Systems The Number of Kanban Card Sets 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 Machine Center Storage Part A Production kanban The process begins by the Assembly Line people pulling Part A from Storage Withdrawal kanban Storage Part A This puts the system back were it was before the item was pulled Assembly Line Material Flow Card (signal) Flow Ou Tang 29 k = Expected DL (1 + S ) = C demand during lead time Size of the container k = Number of kanban card D = Average demand over a time period L = lead time to replenish an order S = Safety factor for the safety stock C = Container size + Safety stock Ou Tang 30 Example Kanban Card Determination A switch assembly is assembled in batches of 4 units from an upstream assembly area and delivered in a special container to a downstream control-panel assembly operation The control-panel assembly area requires 5 switch assemblies per hour The switch assembly area can produce a container of switch assemblies in 2 hours k DL(1 + S ) 5(2)(1.1) = = = C , or 3 Safety stock has been set at 10% of needed inventory Always round up! Ou Tang 31 Ou Tang 32

9 Properties of Kanban systems Key elements in just-in-time Preconditions High High demand rate rate Small variations in indemand Limited number of of product variants Good supplier relations Limitations Unlevelled demand Long setup times Expensive parts parts Large items A match of product design to market demand Product families and flow based manufacturing The relationship with suppliers in a JIT environment Ou Tang 33 Ou Tang 34 Supplier relations Improving example - general electric healthcare Traditional American approach: Market focus in incombination with heavy cost emphasies puts pressure on on suppliers to to reduce costs and a new supplier is isselected if if he he can offer a lower price. Japanese (JIT) approach: The supplier identifies himself with the the customer. Key words in inthese relations are are continuity and flexibility, i.e. i.e. if if the the conditions change the the supplier and the the customer are are developed together to to face the the new challenges. Ex: A customer demands JIT-deliveries every second day instead of of every second week. Insert Finished tube (insert + lead case) Tube on medical system Ou Tang 35 Ou Tang 36

10 Assembly Casing Line, Buc,, France 1 Finished product X-Ray Tubes workshop, BUC BUC GEODIS Insert Components PACKAGING FUNCTIONAL RECEPTION TEST AREA FLUSH & BACKED FILL OUT Casing Raw Materials Finished tube GREEN PARTS Workstations Parts Shelf RECEPTION RECEPTION AREA AREA Insert INSERT BUC CASE ASSEMBLY Ou Tang CLEANING 37 RG Parts 1 Ou Tang 38 2 Supermarket for Managing Assembly Components Finished product BUC GEODIS PACKAGING TEST BACKED OUT FLUCH & FILL BUC RECEPTION AREA Empty KIT CASE ASSEMBLY SUPER MARKET RG IN RG kit OUT Green kit OUT INSERT GREEN Parts Ou Tang 39 Filled Ou Tang KIT 40 CLEANING RM-RG