3M: Muda, Mura, Muri

Lean aims to identify and eliminate waste from work processes. To do so, Lean businesses focus on the 3Ms. In Japanese, the 3Ms are:

  • Muda
  • Mura
  • Muri

Muda means waste, anything that does not add value to the end product. The 8 types of waste are:

  1. Defects
    Flaws in the end product.
  2. Waiting
    Time people spend waiting for the next step in a process to start, waiting for information, or waiting for materials.
  3. Extra motion
    Unnecessary movement by people.
  4. Excess inventory
    Holding more parts, materials, or products on hand than needed. Having excess inventory can be costly, as storage space costs money and items can become obsolete before they are used.
  5. Over-production
    Like having excess inventory, producing too much of a product can result in storage costs and obsolete products.
  6. Extra processing
    Performing more tasks than are necessary to complete a product. For example, cleaning something twice or filling out more paperwork than necessary.
  7. Unnecessary transportation
    Moving materials or products more than necessary.
  8. Unutilized talent
    Some people consider the knowledge or skills of workers a type of waste if they aren't utilized.

Mura means unevenness. This means production may be high sometimes and low other times, resulting in people rushing to get things done or waiting around for more work. Uneven levels of production can result in machine breakdowns, worker fatigue, and other problems. Lean workplaces try to level the workload to prevent these issues.

Muri means overburdening people or equipment. When your processes are asked to handle more work that they can safely do, dangerous situations can arise. Leveling the workload and not assigning more work than is feasible can prevent this.

Mura and muri means uneven workloads and overburdening of resources—can lead to the 8 types of muda. Consequently, Lean organizations should focus on reducing all three Ms.

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