Mura (Japanese term)
From Wikipedia, the free encyclopedia
Mura (無駄) is a Japanese term for unevenness. It is also a key concept in the Toyota Production System and is one of the three types of waste (Muda, Muri) it identifies. Waste reduction is an effective way to increase profitability.
Mura is avoided through Just-in-Time systems which are based on little or no inventory, by supplying the production process with the right part, at the right time, in the right amount, and first-in, first out component flow. Just-in-Time systems create a “pull system” in which each sub-process withdraws its needs from the preceding sub-processes, and ultimately from an outside supplier. When a preceding process does not receive a request or withdrawal it does not make more parts.
For example:
- The Assembly line “makes a request to,” or “pulls from” the Paint Shop, which pulls from Body Weld.
- The Body Weld Shop pulls from Stamping.
- At the same time, requests are going out to suppliers for specific parts, for the vehicles that have been ordered by customers.
- Small buffers accommodate minor fluctuations, yet allow continuous flow.
If parts or material defects are found in one process, the Just-in-Time systems force the problem to be quickly identified and corrected.
A Just-in-Time system delivers clear results:
- Quality is confirmed at every step, through first-in, first-out flow,
- Cost is reduced by eliminating the need for warehousing, as well as the expense of scrapping warehoused parts that are found to be defective. The need for extra labor costs is also eliminated.
- Maximum productivity is a result when the right parts and materials are supplied at the right time and in the right amount.
[edit] Implementation
Production levelling and frequent deliveries to customer are key to identifying and eliminating Mura. The use of diffenet types of Kanban to control inventory at different stages in the process are key to ensuring that "pull" is happening between sub-processes. The use of Heijunka will aid in scheduling work in a standard way that encourages lower costs.
