[Total: 1    Average: 4/5]
At the very essence of Lean, we find the desire to structure a process of reduction and elimination of wastes (Muda), variability and improbabilities (the 3 MU).


All of these words, Muda Muri Mura, define tasks that are ultimately waste of time *, matter…

The MUda

Muda represent the set of wastes that a company can ” produce “. By definition, Muda are all activities that do not add value.

any activity for which the customer does not pay. »-Taiichi OHNO

They were identified by Toyota and numbered 7. A Mnemotechnique way to keep them is “It’sNOW TIME to eliminate Muda“:

  • N: no quality
  • O: over production
  • W: Waiting
  • T: Transport
  • I: Inventories
  • M: Motions
  • E: In excess processing

Muda or Muda??

Most of us do not know, but the term Muda can be written in various ways while in an identical pronunciation and have 2 different senses:

If Muda is spelled in the Katakana * (ム ダ) alphabet, this indicates that there are unnecessary elements inside a process.

If Muda is written with the hiragana alphabet (む だ) *, it means that the entire process is unnecessary.

It is here a subtlety of Taiichi OHNO who liked to play with this language specificity. Indeed, it is very important to be able to make this distinction because what it is used to remove Muda in a process that is itself a Muda.

* Japanese language can be written in various alphabets. Depending on the alphabet used, a single spoken word can have various meanings.

The Muda of overproduction

As the name implies, the overproduction Muda defines any activity intended to produce more than the demand or too early in relation to the demand. This phenomenon often finds its source by the so-called ‘ aIf you. I make more times… “:

  • “That we are missing”
  • “The machine Fails”

This Muda is considered to be the most critical because it necessarily induces all other Muda.

In production

In offices

Many stocks of initial products, outstanding or at the end of the process

Difficulty in knowing what the customer really wants

Constantly rotating Machine

Information that can induce misinformation.

Plethora of the same information (mail, fax, telephone…).

More files, emails, or supplies…

E-mail with too many recipients blocking the boxes and poorly “ read ” (too many recipients can cause the fact that nobody reads it because ” the other will treat it”).

Unnecessary, untapped or misunderstood indicators.

function of software in addition and which do not serve.

The Muda of stock

This Muda is induced by a Muda of overproduction. Stocking has the effect of declining cash flow: the various economic crises have been sleeping and already able to put forward the problems of business cash.

Beyond that, the stock Muda has psychological issues. It allows to ” show ” that we work, to make sure that we can deliver the expected work, to be able to deliver the client… and consequently, it helps to hide the problems.

In production

In offices

Too large useful surfaces

Many transport equipments: truck, pallet…

Time to search for important products or tools

Many small stocks

Overloaded Display and communication boards

batch-initiated work

Congested traffic Area

Expired products or problems with traceability (FIFO not respected)

Time to search for important information

Cupboard full of files or supplies

Overloaded Display and communication boards

Many supplies

batch-initiated work

The Muda of transport

It represents all the transport of information, products… from one place to another or from one process to another (transport of files between offices, transport to the photocopier, transport to the packaging…). It induces:

  • Time loss
  • Increased chances of loss, deterioration or accident

In production

In offices

Many transport equipments: truck, pallet…

Many operator in ” movement

Remote Posts

Many intermediate and transfer area storages

Production flow not clear

Many document transfers between offices

Many operator in ” movement

Remote offices

Here is an example of a transport Muda where all the movements carried out by the bales do not bring any added value.

The Waiting Muda

It represents the whole time of non-added value caused resulting in the expectation of a person, of something. It is good to remember that the expectation is not “ always ” of rest. It can generate nerves, stress, fatigue… Who has never ” squealed ” in front of his computer that “struggle“?

In production

In offices

operator who “ controls ” a machine that rotates

Machine shutdown due to material expectation

Waiting for a decision

Task imbalance between processes

Rate below standards

Waiting for validation to continue the process

Waiting for photocopier or fax repairer

Waiting to open a computer file

The Muda of movement

It represents all the superfluous movements. These movements can be human, material or even machine movements.

It is important to remember that “to move, does not mean to work “. Moving means simply that we are moving and that by the same, these movements can induce MSD and increase the likelihood of incidents.

In production

In offices

Non-optimized line locations

Lifting, moving or carrying heavy loads

Leaning, turning…

Non-Optimized PLC program

Numerous work stoppages for joint problem (MSD)

Lifting, moving or carrying heavy loads

Insufficient lighting that sometimes requires a lamp

Noise or significant air flow requiring staff not to pass through this area

Leaning, turning…

The Muda of process

It represents the superfluous processes/tasks/actions relative to the customer request, either too much or missing.

In production

In offices

Multiplication of controls

Machining of parts too precise

Duplicate processes: I do, I remake, I undoing, it’s always working…

Inadequate or non-existent Standards

A lot of variability

Multiplication of validations

Too high quality paper

Duplicate processes: I do, I remake, I undoing, it’s always working…

Inadequate or non-existent Standards

The Muda of faults

It represents the set of defects that a process can produce. These are non-compliances, customer complaints, errors, scraps… and generates:

  • Unhappy customers if the product arrives to the customer
  • Waste of time: illegible fax, parts to be restarted…
  • Extra costs: The non-quality, we always pay it twice, once to do it, once to repair it.
  • Material losses: Unrecoverable product to be scrapped…

In production

In offices

Customer claim

Many scraps

Standardized Recovery area


Customer claims

Quote or invoice calculation errors

Bad send address

Other classifications


Historically, we hold this classification of the 7 types of Muda. For culture, we know three other classifications:

  • Yasuhiro Monden : Excessive production resource, overproduction, Stock, useless investment.
  • Hiroyuki Hirano : Classification According to the 5M, each M representing a potential source of waste.
  • Hitoshi Yamada: This disciple of Ohno proposes the Muda of transport, movement and stagnation.

Muda Hunting

  1. Eradicating obvious wastes.
  2. Refined Identification of value-added tasks for Non-value-added tasks. For this, we will use a graphical tool, the Yamazumi (example opposite) as well as the DPAapproach. These same non-value-added tasks will have to be distinguished as removable or non-removable. In this step, you will be able to eradicate the tasks of non-value-added suppressable.
  3. Finally, you will be able to handle non-value-added tasks that are not removable. These can be put under control and/or minimized.

The key indicator of Lean: EFFICIENCY

For the calculation of total time of operations, there are 2 practices:

  • Either take the operations being on the critical path.
  • Or take all the operations of the process.

The second practice is more “hard” than the first. It will be selected in cases where non-critical path operations generate Muda while not in use.

An example of Muda hunting: Who has never been annoyed with the waiting time in the emergency services, at the doctor, at the taxes… By implementing the principles of Lean and hunting for Muda, some institutions in Quebec have set up “virtual waiting“.

The operation is very simple: you arrive at your doctor, you sign up in the queue, then you are informed in real time of the number of people standing in front of you. You don’t have to stay in the waiting room and you can go shopping, phone…

8th Muda: Talents

In some companies (PSA…), an 8th Muda appeared: The Muda of talent2. Highlighted in the years 2000 by Norman Bodek, this Muda defines all the wastes related to the management of skills especially in the case of untapped talents.

The skills of the person are not used wisely and the consequences are numerous: loss of motivation, project that goes wrong… It is very often an important source of loss of added value.

The 9th Muda: The Overdesign

The Overdesign Muda corresponds to the incorporation of superfluous function see unnecessary for the customer at any given time. There are 3 types of overdesign Muda:

  • Poor market/Product synchronization: One of the problems of an innovative product is the launch at the right time on the market. Arriving too early on a market, a useful product is Muda. It will only be once these features are accepted by the market that it will no longer be considered Muda3.
  • Superfluous function: What the Japanese call the Chindogu. They are objects with superfluous functions. Let’s take an example of the invention of the fork that turns to eat the spaghetti.
  • Overdesign of functions: one conceives a product with too much functionality compared to the need. Microsoft Excel is an example. Number of studies show that 90% of the population uses only 10% of the software’s functionality.
  • Technology overdesign: How much product uses far too advanced and too complex technologies. An example with the electric Derailleur Mektronic launched in 1996, with which we could accidentally change the gears of our partner. The 3g phone, the latest on the market, was launched while the technology was not working.

The 10th Muda: Communication

Probably the most common muda in a society that has become communication. What employee does not go today on the Internet to visit sites, exchange files…? Which employees do not spend hours sending e-mails? What manager does not waste time reading a number of parasitic e-mails? What manager has not wasted time in unnecessary meetings?…

MUri 無理

The MUri defines the idea of a few things irrational, unreasonable… It is a quantity or difficulty of work too large compared to the current (human, machine):

  • Loads too heavy for people
  • Unreasonable work objective

Beyond the induced MUda, the main consequences are the risks of accidents, stress, defects and MSD.

MUra むら

The MUra defines all irregularities and variability in the work. In a banking agency, this can be for example the waiting time between two clients when there are no more. In production workshops It is for example the machine downtime due to a material expectation.

These beatings and rhythm cuts induce to find solutions to hide the MUra (buffer, pending folder stored when one has nothing more to do…), which themselves are sources of MUda. The challenge is to put in place a smooth and harmonious flow of work.


1-H. Ford (1926)-Today and Tomorrow

2-A. Morais, R. Aubineau (2012)-Articulation between ergonomics and Lean manufacturing at PSA

3-J. Y. Prax (2005)-Objective: Innovation

F. Gillet-Goinard, L. Maimi (2007)-All production function

Mr. Eaton (2013)-The Lean Practitionners Handbook

Share This