Copyright 2006 John Wiley & Sons, Inc. Beni Asllani University of Tennessee at Chattanooga Lean Systems Operations Management Chapter 16 Roberta Russell & Bernard W. Taylor, III

Waste in Operations (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

Seven Wastes  Overproduction  Queues  Transportation  Inventory  Motion  Over-processing  Defective product A broader perspective suggests other resources like energy and water are wasted but should not be

Copyright 2006 John Wiley & Sons, Inc.16-4 Lean Production   Doing more with less inventory, fewer workers, less space   Just-in-time (JIT) smoothing the flow of material to arrive just as it is needed “JIT” and “Lean Production” are used interchangeably   Muda waste, anything other than that which adds value to the product or service

Copyright 2006 John Wiley & Sons, Inc.16-5 Implementing Lean Production  Use lean production to finely tune an operating system  Somewhat different in USA than Japan  Lean production is still evolving  Lean production isn’t for everyone

Copyright 2006 John Wiley & Sons, Inc.16-6 Benefits of Lean Production   Reduced inventory   Improved quality   Lower costs   Reduced space requirements   Shorter lead time   Increased productivity

Copyright 2006 John Wiley & Sons, Inc.16-7 Benefits of Lean Production (cont.)   Greater flexibility   Better relations with suppliers   Simplified scheduling and control activities   Increased capacity   Better use of human resources   More product variety

Copyright 2006 John Wiley & Sons, Inc.16-8 Cellular Layouts   Manufacturing cells comprised of dissimilar machines brought together to manufacture a family of parts   Cycle time is adjusted to match takt time by changing worker paths

Copyright 2006 John Wiley & Sons, Inc.16-9 Pull Versus Push Systems  A pull system uses signals to request production and delivery from upstream stations  Upstream stations only produce when signaled  System is used within the immediate production process and with suppliers

Copyright 2006 John Wiley & Sons, Inc Pull Versus Push Systems  By pulling material in small lots, inventory cushions are removed, exposing problems and emphasizing continual improvement  Manufacturing cycle time is reduced  Push systems dump orders on the downstream stations regardless of the need

Just-In-Time (JIT) Defined  JIT 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).  JIT also involves the elimination of waste in production effort.  JIT also involves the timing of production resources (e.g., parts arrive at the next workstation “just in time”).

Copyright 2006 John Wiley & Sons, Inc Quality at the Source   Visual control makes problems visible   Poka-yokes prevent defects from occurring   Kaizen a system of continuous improvement; “change for the good of all”   Jidoka authority to stop the production line   Andons call lights that signal quality problems   Under-capacity scheduling leaves time for planning, problem solving, and maintenance

Copyright 2006 John Wiley & Sons, Inc Kanbans  Card which indicates standard quantity of production  Derived from two-bin inventory system  Maintain discipline of pull production  Authorize production and movement of goods

Copyright 2006 John Wiley & Sons, Inc Types of Kanban   Production kanban authorizes production of goods   Withdrawal kanban authorizes movement of goods   Kanban square a marked area designated to hold items   Signal kanban a triangular kanban used to signal production at the previous workstation   Material kanban used to order material in advance of a process   Supplier kanban rotates between the factory and suppliers

Copyright 2006 John Wiley & Sons, Inc Small Lots  Require less space and capital investment  Move processes closer together  Make quality problems easier to detect  Make processes more dependent on each other

Copyright 2006 John Wiley & Sons, Inc Inventory Hides Problems

Copyright 2006 John Wiley & Sons, Inc Less Inventory Exposes Problems

Copyright 2006 John Wiley & Sons, Inc Total Productive Maintenance (TPM)  Designing machines that are reliable, easy to operate, and easy to maintain  Emphasizing total cost of ownership when purchasing machines so that service and maintenance are included in the cost  Developing preventive maintenance plans that utilize the best practices of operators, maintenance departments, and depot service  Training workers to operate and maintain their own machines

Copyright 2006 John Wiley & Sons, Inc Total Productive Maintenance (TPM)  Breakdown maintenance Repairs to make failed machine operational Repairs to make failed machine operational  Preventive maintenance System of periodic inspection and maintenance to keep machines operating System of periodic inspection and maintenance to keep machines operating  TPM combines preventive maintenance and total quality concepts

Copyright 2006 John Wiley & Sons, Inc Maintenance  Two types of maintenance  Preventive maintenance – routine inspection and servicing to keep facilities in good repair  Breakdown maintenance – emergency or priority repairs on failed equipment

Copyright 2006 John Wiley & Sons, Inc How Maintenance is Performed Figure 16.5 Operator Maintenance department Manufacturer’s field service Depot service (return equipment) Preventive maintenance costs less and is faster the more we move to the left Competence is higher as we move to the right