In Lean there are 3 types of waste: Mura (unevenness), Muri (overuse) and Muda (actual waste).
People often use acronyms like DOWNTIME or TIMWOOD (amongst others) to remember the various forms of muda.
We can reengineer the list to facilitate recall and to better structure and understand them.
- Defects which result in discarded items and rework
Three AMOUNT wastes:
- Excessive processing including components or products that are higher quality than required, or processes that are poorly designed and require too much work [inside process]
- Over production of too much product before it's needed [outside process]
- Inventory of raw materials, components, work in progress and finished products (can result from excessive raw materials, over production, inconsistent flow, etc) [result]
Three MOVEMENT wastes:
- Motion within processes, which cause equipment wear, worker strain or fatigue, inefficiencies [inside process]
- Transport between processes, like time spent on conveyor belts or trucks [outside process]
- Waiting, like time spent in stacks or in-trays [result]
- Wasted talent. Since employee input into kaizen is essential, this 8th waste probably earns its place in the list.
Examining waste is an excellent approach to Kaizen. But sometimes it can result in incremental, sub-optimal change compared to a reengineering approach that seeks the shortest path to the desired outcome.
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