is a
Japanese
Japanese may refer to:
* Something from or related to Japan, an island country in East Asia
* Japanese language, spoken mainly in Japan
* Japanese people, the ethnic group that identifies with Japan through ancestry or culture
** Japanese diaspor ...
word meaning "unevenness; irregularity; lack of uniformity; nonuniformity; inequality", and is a key concept in the
Toyota Production System
The Toyota Production System (TPS) is an integrated socio-technical system, developed by Toyota, that comprises its management philosophy and practices. The TPS is a management system that organizes manufacturing and logistics for the automobile ma ...
(TPS) as one of the three types of waste (''
muda
Muda or MUDA or MuDA may refer to:
People
* Sultan Muda (1579–1579), nominal Sultan of Aceh
* Tycho Muda (born 1988), Dutch rower
* Vincent Muda (born 1988), Dutch rower
Places
* Muda, Estonia, a village
* Mudá, Spain
*Muda River, Malaysi ...
'', ''mura'', ''
muri'').
Waste in this context refers to the wasting of time or resources rather than wasteful by-products and should not be confused with
Waste reduction
Waste minimisation is a set of processes and practices intended to reduce the amount of waste produced. By reducing or eliminating the generation of harmful and persistent wastes, waste minimisation supports efforts to promote a more sustainab ...
.
Toyota
is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 ...
adopted these three Japanese words as part of their product improvement program, due to their familiarity in common usage.
Mura, in terms of business/process improvement, is avoided through
Just-In-Time systems which are based on keeping little or no inventory. These systems supply the production process with the right part, at the right time, in the right amount, using
first-in, first-out
Representation of a FIFO queue
In computing and in systems theory, FIFO is an acronym for first in, first out (the first in is the first out), a method for organizing the manipulation of a data structure (often, specifically a data buffer) where ...
(FIFO) 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. This type of system is designed to maximize
productivity
Productivity is the efficiency of production of goods or services expressed by some measure. Measurements of productivity are often expressed as a ratio of an aggregate output to a single input or an aggregate input used in a production proces ...
by minimizing storage overhead.
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 approach requires that the problem be quickly identified and corrected.
Implementation
Production leveling
Production leveling, also known as production smoothing or – by its Japanese original term – , is a technique for reducing the mura (unevenness) which in turn reduces muda (waste). It was vital to the development of production efficiency in ...
, also called
heijunka
Production leveling, also known as production smoothing or – by its Japanese original term – , is a technique for reducing the mura (unevenness) which in turn reduces muda (waste). It was vital to the development of production efficiency in ...
, and frequent deliveries to customer are key to identifying and eliminating Mura. The use of different types of
Kanban
Kanban (Japanese: カンバン and Chinese: 看板, meaning signboard or billboard) is a scheduling system for lean manufacturing (also called just-in-time manufacturing, abbreviated JIT). Taiichi Ohno, an industrial engineer at Toyota, develope ...
to control inventory at different stages in the process are key to ensuring that "pull" is happening between sub-processes. Leveling production, even when different products are produced in the same system, will aid in scheduling work in a standard way that encourages lower costs.
It is also possible to smooth the workflow by having one operator work across several machines in a process rather than having different operators; in a sense merging several sub-processes under one operator. The fact that there is one operator will force a smoothness across the operations because the workpiece flows with the operator. There is no reason why the several operators cannot all work across these several machines following each other and carrying their workpiece with them. This multiple machine handling is called "multi-process handling" in the Toyota Production System.
Another means of detecting and reducing Mura is increasing the process' standardization - ensuring that all workers understand and can handle each type of request that they come across along a clear, step-by-step protocol. Working to simplify the process as much as possible will also help to drive down the unevenness-generating complexities. You can also aid variability detection by performance monitoring through histograms and statistical
control charts
Control charts is a graph used in production control to determine whether quality and manufacturing processes are being controlled under stable conditions. (ISO 7870-1)
The hourly status is arranged on the graph, and the occurrence of abnormalit ...
.
Limitations, critiques and improvements
Some processes have considerable
lead time
A lead time is the latency between the initiation and completion of a process. For example, the lead time between the placement of an order and delivery of new cars by a given manufacturer might be between 2 weeks and 6 months, depending on vari ...
. Some processes
have unusually high costs for waiting or downtime. When this is
the case, it is often desirable to try to predict the upcoming demand
from a sub-process before pull occurs or a card is generated. The smoother
the process, the more accurately this can be done from analysis of
previous historical experience.
Some processes have asymmetric cost. In such situations, it may
be better to err away from the higher cost error. In this case,
there appears to be waste and higher average error, but the waste
or errors are smaller ones and in aggregate leads to lower costs /
more customer value.
For example, consider running a call center.
It may be more effective to have low cost call center operators wait for
high value clients rather than risk losing high value clients by making
them wait. Given the asymmetric cost of these errors - particularly if
the processes are not smooth - it may be prudent to have what seems like
a surplus of call center operators that appear to be "wasting" call center
operator time, rather than commit the higher-cost error of losing the
occasional high value client.
See also
*
Fukushima Daiichi nuclear disaster
The was a nuclear accident in 2011 at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan. The proximate cause of the disaster was the 2011 Tōhoku earthquake and tsunami, which occurred on the afternoon of 11 March 2011 and ...
, this disaster is said to be caused by "nuclear mura".
References
{{Reflist
Japanese business terms
Lean manufacturing