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materials and work-in-progress is
considered wasteful because of the
associated space and staff costs.
The third type of muda that
Shingo identified is movement. In
some factories, workstations are
badly designed, and employees
spend time doing things that do not
add value to the product, such as

looking for tools, walking from one

part of the factory to another, or

bending to pick up parts. This type

of waste increases cycle time—the

time taken to produce a unit of

output. Longer cycle times lead to

lower productivity, which in turn

drives up unit labor costs.

The fourth muda is time spent

waiting. Delays may occur when

machines on a production line are

poorly coordinated, resulting in

bottlenecks. Time might also be

wasted resetting machinery to

produce a different part.

The fifth muda is transportation.

Time and money spent moving

work-in-progress from one factory

to another will drive up costs, and

this is unlikely to add value to the

product, so it is wasteful.

The sixth example of muda is

overprocessing. Consumers will

only pay for the product features

that they value. Producing complex,

overengineered products is wasteful

because it creates additional costs

without any extra revenue.

LEAN PRODUCTION

Holding goods in stock is a cost for
a company, since warehouse space
and employees need to be paid for. In
addition, cash tied up in stock could be
in the bank instead, earning interest.

The final muda is the production

of defective items. Substandard

products signify waste of time and

resources, and mean that further

inspection processes are required

and the products must be reworked.

In addition to the seven types of

muda, Toyota identifies two other

potential problems: mura and muri.

Mura is uneven flow in a process,

leading to unbalanced working

practices. Muri is the overburdening

of people or equipment.

Lean strategy

Using these insights, production

engineer Taiichi Ohno developed

the Toyota Production System

(TPS). This lean production method

counters waste in the production

process by producing more using

less. It enables a manufacturer to

increase output without having to

pay for extra labor, raw materials, or

capital. Alternatively, a business

can use lean production techniques

to make a better-quality product

that will sell for a higher price.

Muri, mura, and muda are three
Japanese terms identified by the
Toyota Production System as
problems to avoid. Muri refers
to the overburdening of
individuals or teams, which
is inefficient; mura means
an unbalanced work flow,
which can cause
bottlenecks in supply;
and muda are all the
areas of waste
in a system.

A just-in-time supply system

eliminates muri, mura, and muda

from the production system, so that

teams receive materials as they

need them and waste is avoided.

MURI

Overburdened

JUST-IN-TIME

MUDA

Waste

MURA

Unbalanced