The Buffering Law observed in Software Engineering

Railway buffer at the top of Pikes Peak, Colorado Springs CO

There is an informative slide deck on the FactoryPhysics website entitled A Fast Cycle Time Story. This slide deck was created by two Intel Products employees namely Tim Skowronski and Joan Tafoya.

The slides cover many aspects of lean manufacturing, one of the topics covered is The Buffering Law

Systems with variability must be buffered by some combination of:

  • Inventory
  • Capacity
  • Time

Tafoya and Skowronski explain the implication of this law

If you cannot pay to reduce variability, you will pay in terms of high WIP, under-utilized capacity, or reduced customer service i.e. lost sales, long lead times, and/or late deliveries.

The following variability buffering examples are provided:

  • Ballpoint Pens:
  • can’t buffer with time (who will backorder a cheap pen?)
  • can’t buffer with capacity (too expensive, and slow)
  • must buffer with inventory
  • Ambulance Service:
    • can’t buffer with inventory (an inventory of trips to hospitals?)
    • can’t buffer with time (response time is the key measure)
    • must buffer with capacity
  • Organ Transplants:
    • can’t buffer with WIP (perishable – very short usable life)
    • can’t buffer with capacity (we cannot ethically increase capacity)
    • must buffer with time

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