Lean Systems and jit lean Production

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Lean Systems and JIT

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”)

Overview of JIT

    • Toyota Production System (post-WWII)
    • reducing costs, eliminating waste, and improving productivity
    • Just-in-Time (1980s)
    • way of planning operations
    • reduces variability of demand
    • enhances responsiveness
    • conducts value-adding operations as close to consumption as possible

JIT and Lean Management

  • 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:
    • human relations, vendor relations, technology, and the management of materials and inventory
  • Little JIT

    • focuses more narrowly on scheduling goods inventory and providing service resources where and when needed

The Toyota Production System

  • Based on two philosophies:

    • 1. Elimination of waste
    • 2. Respect for people

Toyota Production System’s Four 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

Waste in Operations

  • Waste from overproduction

  • Waste of waiting time

  • Transportation waste

  • Inventory waste

  • Processing waste

  • Waste of motion

  • Waste from product defects

  • Underutilization of people


  • Take an activity from a job or personal life (e.g. a sport, study, Muhlenberg processes, a class)

  • Identify areas of waste

  • Identify opportunities for eliminating waste and improving the performance

  • Write down and share with the class

Minimizing Waste: Inventory Hides Problems

JIT Demand-Pull Logic


    • Supplier structural improvements
    • reduced inventory at suppliers results in lower fixed costs
    • suppliers provide small quantities with frequent deliveries
  • Supplier infrastructural improvements

    • emphasis on win-win relationship


    • JIT planning and control:
    • relies on a level master schedule
    • prefers excess capacity to excess inventory
    • works with suppliers and customers to reduce complexity & uncertainty
    • improves system’s responsiveness to customer requirements

JIT in Services (Examples)

  • Organize Problem-Solving Groups

  • Upgrade Housekeeping

  • Upgrade Quality

  • Clarify Process Flows

  • Revise Equipment and Process Technologies

  • Level the Facility Load

Supplier Networks: Trends In Supplier Policies

  • 1. Locate near to the customer

  • 2. Consider establishing small warehouses near to the customer or consolidating warehouses with other suppliers

  • 3. Use standardized containers and make deliveries according to a precise delivery schedule

  • 4. Become a certified supplier and accept payment at regular intervals rather than upon delivery

Potential Supplier Concerns with JIT Purchasing

  • Desire for diversification

    • -- concerned about all business stemming from single customer.
  • Poor customer scheduling

    • -- concerned that customer will be unable to develop smooth, consistent schedule.
  • Engineering changes

    • -- concerned that customer will promulgate frequent engineering changes with inadequate lead time.

Critique of JIT

  • Contrast pragmatic JIT vs. romantic JIT

  • Pragmatic JIT

    • focuses on concrete details of production process
    • use practical tools to address problems
    • continuous improvement
  • Romantic JIT

    • appeals to “revolutionary rhetoric”
    • cutting inventories is a prompt to reform
    • against tradeoffs

Critique of JIT

  • Problems

  • System of beliefs and collection of methods

  • Successes due to genius of Ohno and Shingo (of Toyota) – they did make tradeoffs

  • Moves inventories to suppliers but does not reduce overall

  • Workers in JIT environments under high levels of pressure -- burn out!

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