Cellular Systems

A kind of Lean approach that seeks to achieve efficiencies by leveraging the similarities between production units.

Characteristics of Cellular Systems

  • No excessive inventory between operations.
  • The ideal cellular design is a Counter-clockwise U-shaped cell.
  • Production paced to takt time.
  • Machines in order of process.
  • Small and inexpensive equipment.
    • use auto eject
    • one touch automation
    • sensors to indicate abnormal conditions
    • design in maintainability
  • Multi-process-handling workers.
  • Materials
    • keep parts near use
    • limit materials at a machine to 2 hour supply
    • use kanban to regulate parts replenishment
    • use gravity to move parts and materials
    • use alternative methods to restock parts
    • dedicated location for stock
    • standardize amount on each shelf
  • Work Stations
    • Eliminate surfaces where things can accumulate
    • optimize bench height
    • adequate lighting
    • minimize travel
    • combined usage tools (Ex Spork!)
  • Human Movement
    • Minimize motion
    • avoid sharp turns
    • standing position promotes flexibility
    • make movement instintual
    • design movements to follow a rythym
    • address ergonomic issues.

Cellular Systems Design

  1. Group Products
    • Establish product families
  2. Establish takt time
  3. Review the work sequence
  4. Combine work elements to balance process
  5. Design the cell layout
    • Physical location of machines should correspond to work sequence
    • U shaped
    • Flow counter clockwise
    • Benefits
      • Improved flow
      • Reduction of inventory build up.

 How to Create Flow

  1. Map current layout and flow
  2. Observe the work sequence of tasks each worker performs
  3. Collect current cycle times
    • Ex. Takt Time.
    • Machine Cycle Time
      • Time it takes for a machine to produce one unit, including the time taken to load and unload.
    • Machine Automatic Time
      • Time it takes for a machine to produce one unit, exclusive of loading and unloading.
    • Operator Cycle Time
      • Time it takes for a person to complete a predetermined set of operations including loading, and unloading. Do not include time waiting.
  4. Identify value-added versus non-value-added elements.
    • Non-value-added waste.
      • Do not include:
        • Walking
        • Out of cycle work for operators.
        • Wait time for machines to cycle.
        • time taken to remove finished parts where automatic ejection could introduced.
  5. Eliminate non-value-added elements.

How Many Operators are Required?

Optimum # operators = Sum of Operator Cycle Time / Takt Time



0 comments… add one

Leave a Comment