Muda, Mura and Muri

Idea

Muda, Mura and Muri is a concept developed by car manufacturer Toyota and is referred to as the 3 M's of waste in lean manufacturing. They collectively describe the practices companies can eliminate of to reduce non-value adding use of resources. These three waste types can be found in both manufacturing and office processes.

Muda

Muda is the Japanese word for "waste" and relates to any activity or practice that does not in any way produce value for the customer. There are, as explained by the so-called "father of the Toyota production system", Taiichi Ohno, 8 categories of waste. Simply eliminating Muda will not be of help to the company without finding the reason for the waste, which will usually correlate with the two other wasteful practices; Mura and Muri.

The eight categories of waste:

- Transportation (relates to the movement of products between locations and operations)

- Inventory (depicts the stock of finished goods, raw material and the Work in Progress (WIP) that a business obtain)

- Motion (details the physical activity of a machine or individual whilst comporting an action)

- Waiting (the operation of waiting for a worker or machine to finish, a delivery to arrive etc.)

- Over-processing (operations produced beyond what the customer call for)

- Over-production (producing higher number of products than what is needed from customers)

- Defects and Rework (product rejection and altering needs within the business operations)

Mura

Mura presents the wastes of unevenness or irregularity and often occurs in linkage with inconsistency in customer demand, cycle times variation and an uneven work pace. It is most often used in relation to material flow, but can also be seen throughout a company's operations and day-to-day activities. The waste of unevenness can often be eliminated by creating and encouraging openness in the supply chain, and is referred to as "levelling" and is often perceived as a counter measure to Mura.

Muri

Links to the waste of overburden by causing unnecessary stress and strain to employees or equipment. Muri can transpire as a result of lack of training, poorly developed workplaces, lack of maintenance, limited focus on safety and non-successful measures of performance.

Application

The three M's in lean manufacturing, Muda, Mura and Muri are often analogous and to eliminate one often means that the others is eliminated simultaneously. By applying various tools such as Kanban, Just in time (JIT) etc. it can strengthen production stream, assisting to reduce Mura, the waste of unevenness. The Trusted Platform Value (TPV) and the 5S methodology are frameworks that can be applied to eliminate the waste of overburden, Muri.

There is no ultimate approach or order on how to reduce the 3 M's, however The Danish Lean Forum has published a recommended elimination process:

1. Reduce Muda

To be able to overcome the three wastes, Mura should be reduced to create more surplus for the Lean practices. By trying to identify the Muda wastes it is also likely that the two other M's will more easily appear.

2. Reduce Mura

To reduce the unevenness waste, companies should aim for a healthy and strong alignment of activities and processes, as this will decrease delay and day-to-day waste time.

3. Reduce Muri

Should be done through competence management and weekly planning meetings. By ensuring follow-up meetings on the planning the process could also be more heavily linked to Kaizen, referring to the continuous improvement approach.