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Chapter 12

Chapter 12. Lean Production. Lean Production The Toyota Production System Lean Implementation Requirements Lean Services. OBJECTIVES. Lean Production.

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Chapter 12

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  1. Chapter 12 Lean Production

  2. Lean Production • The Toyota Production System • Lean Implementation Requirements • Lean Services OBJECTIVES

  3. 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”)

  4. Pull System (exhibit 12.1)

  5. Features of Lean Production (exhibit 12.2)

  6. The Toyota Production System Based on two philosophies: • Elimination of waste • Respect for people

  7. Elimination of Waste • Focused factory networks • Group technology • Quality at the source • JIT production • Uniform plant loading • Kanban production control system • Minimized setup times

  8. Focused Factory Networks These are small specialized plants that limit the range of products produced (sometimes only one type of product for an entire facility) Most plants in Japan have between 30 and 1000 employees Coordination System Integration

  9. Group Technology (reduce movement and waiting time)

  10. Quality at the Source means doing it right the first time and, when something goes wrong, stop the process or assembly line immediately.JIT Production means producing what is needed when needed and no more. Inventory hides problems.

  11. Uniform Plant Loading (heijunka) Suppose we operate a production plant that produces a single product. The schedule of production for this product could be accomplished using either of the two plant loading 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 uniform loading help save labor costs?

  12. Kanban Production Control System is an inventory or production control system that uses a signaling device to regulate flows

  13. Determining the Number of Kanbans Needed • Setting up a kanban system requires determining the number of kanban cards (or containers) needed • Each container represents the minimum production lot size • An accurate estimate of the lead time required to produce a container is key to determining how many kanbans are required. Let k = Number of kanban card sets (a set is a card) D = Average number of units demanded over some time period L = lead time to replenish an order (same units of time as demand) S = Safety stock expressed as a percentage of demand during lead time C = Container size k = DL(1+S)/C

  14. Solved Problem A local hospital wants to set up a kanban system to manage its supply of blood with the regional blood bank. Blood is measured by the pint and is shipped in containers that contain six pints each. For a particular blood type, the hospital uses an average of 12 pints per day. The hospital also carries a safety stock of two days’ expected demand. How many kanban cards should the hospital use for the type of blood? D = 12 pints per day, L = 1 day, S = 200%, C = 6 pints k = DL(1+S)/C=12*1*(1+200%)/6=6 This means that six kanban cards are needed. Each time a new container of blood is opened, a card should be sent to purchasing and another six pints of blood be ordered. When the blood is received, the card is attached to its container.

  15. Respect for People • Cooperative employee unions • Subcontractor networks Four unwritten rules: • All work shall be highly specified as to content, sequence, timing, and outcome • Every customer-supplier connection must be direct, and there must be an unambiguous yes-or-no way to send requests and receive responses • The pathway for every product and service must be simple and direct • 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

  16. Lean Implementation Requirements • Lean Layouts and Design Flows: Lean requires the plant layout to be designed to ensure balanced work flows with a minimum of work-in-process inventory, and reduced setup cost.

  17. Lean Applications for Job Shops: Although job shops are characterized by low volume and high variety, lean can be used if the demand can be stabilized to permit repetitive manufacture. • Lean Applications for Line Flows: In a pure lean environment, no employee does any work until the product has been pulled by the market.

  18. Total Quality Control: The practice of building quality into the process and not identifying quality by inspection. • A Stable Schedule: Lean production requires a stable schedule over a long time. • Work with Suppliers: If a firm shares its projected usage requirements with its vendors, they will be able to develop a level production system.

  19. Lean Services (Examples) • Organize Problem-Solving Groups • Upgrade Housekeeping • Upgrade Quality • Clarify Process Flows • Revise Equipment and Process Technologies • Level the Facility Load • Eliminate Unnecessary Activities • Reorganize Physical Configuration • Introduce Demand-Pull Scheduling • Develop Supplier Networks

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