muda in manufacturing

While searching the web this morning I failed to find a clear and succinct definition or explanation of the seven types of muda (waste), as originally identified by Toyota. So for reference I’ve compiled the following using a combination of various textbooks on my bookshelf:

Over-production
Producing more than necessary results in consumption of raw materials before they are needed; wasteful use of manpower and utilities; additions of machinery; increased interest burdens; increased inventory (below); increased transportation and admin costs.
Inventory or Work-in-Progress (WIP)
Final products, work in progress, parts and supplies all add to the cost of operations by consuming space, facilities, manpower and admin. Their quality also deteriorates over time, and they may even be destroyed by a fire or other disaster.
Transportation
Moving materials or products adds no value. Worse, damage often occurs during transport.
Repair / Rejects
Rejects interrupt production and require expensive rework. Often the rejects must be discarded, thus wasting the resources and effort that went into their creation. The rejects themselves may also damage machinery.
Motion
Any motion of a person’s body not directly related to adding value is unproductive. Unnecessary or awkward operator motions put undue stress on the body and cause waste.
Over-processing
Sometimes inadequate technology or design leads to muda in the processing work itself. For example, the apparent need to wrap WIP in bubble-wrap for transportation to another machine could be eliminated by re-designing the assembly line.
Waiting
Waiting occurs when the hands of the operator are idle; when an operator’s work is put on hold because of line imbalances, lack of parts or machine downtime; or when the operator is simply monitoring the machine as it adds value.

(Main sources: Toyota Production System: Beyond Large-scale Production and Gemba Kaizen: A Commonsense Low Cost Approach to Management)

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One thought on “muda in manufacturing

  1. Pingback: people problems vs process problems « silk and spinach

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