The Psychology of Quality and More

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Muda means waste, where waste is any activity that does not add value. Reducing or eliminating muda is, of course, one of the fundamental objectives of any quality-oriented person.

Taichi Ohno of Toyota identified what are called the seven wastes or seven mudas, being the most common form of muda found:

  • Waste from overproduction

    • Which leads to excess inventory, paperwork, handling, storage, space, interest charges, machinery, defects, people and overhead.
    • It is often difficult to see this waste as everyone seems busy.
  • Waste of time in waiting

    • People may be waiting for parts or instructions.
    • Mostly they are waiting for one another, which often happens because they have non-aligned objectives.
  • Transportation waste

    • Poor layouts lead to things being moved multiple times.
    • If things are not well place, they can be hard to find.
    • It can aggravate alignment of processes. 
  • Processing waste

    • Additional effort may be required in an inefficient process.
  • Inventory waste

    • Excess buffer stocks a whole host of sins, which will be uncovered by gradually lowering inventory (doing it all at once will cause total breakdown!).
  • Waste of motion

    • This includes movement of people, from simple actions when in one place to geographic movement. Having everything to hand as it is needed reduces motion muda.
  • Waste from product defects

    • Defects cause rework, confusion and upset a synchronized set of processes.

A simplified view of muda is:

  • Wasting time.

  • Wasting a consumable resource, such as materials.

  • Causing dissatisfaction (including incomplete satisfaction).

Muda is one of the '3Ms': muda, or waste, mura, meaning irregular, uneven or inconsistent, and muri, meaning unreasonable or excessive strain.

The acronym 'DOT WIMP' can be used to remember Muda wastes (Defects, Overproduction, Transportation, Waiting, Inventory, Motion, Processing).

A variant on Mudas is sometimes called the '8 Wastes of Lean', changing 'processing' to 'over-processing', and adding under-use of skills. This has the acronym 'TIM WOODS' (Transport, Inventory, Motion, Waiting, Over-production, Over-processing, Defects, Skills).

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