Muda, Mura and Muri

These three names, Muda, Mura and Muri do not sounds familiar to our normal language slang because these are the Japanese words. Muda is the Japanese word for waste, Mura is the Japanese word for unevenness and, Muri is the Japanese word for Overburden. These words represents anything, which is against lean manufacturing.

So, initially we must know what all things to be eliminated from a manufacturing process, for upgrading it to a lean manufacturing process. And that’s the importance of this article and let’s go deep in to this. We will also discuss, how Muda, Mura and Muri is against lean manufacturing.

The very first company to use these terms was Toyota, they described the 3M (Muda, Muri, and Mura) as the culprit for any inefficiency in the process. The Toyota Production System also started developing ways to handle the 3M to have an efficient working system.

All the three Muda, Mura and Muri are collectively considered as waste, therefore, Toyota Production System focuses on lean methodology to develop the “Waste Elimination Culture”.

What is muda

Muda is any material or operation or activity, which do not add any value to the customer requirement. We can classify muda into 8 types and those are explained in detail and clearly in one of my previous article, 8 Wastes In Lean Manufacturing. I request you to read that article and come back.

How can we identify muda

Adding some points on how to identify muda;

1. Too many movements of materials, which may due to poor layout, multiple storerooms, or some other reasons, definitely there will be waste of transportation.
2. If there are unnecessary movements of workers looking for tools, materials, and other necessary items due to poor layout and this movement is a waste of time and energy of operators as this adds no value to the product.
3. If an operator is watching and waiting for the machine to complete the particular process or machines halted due to breakdown, or setup, this does not add any value to the system and is considered as waste.
4. Producing more than demand or batch processing or material overflow adds no value to the system. Even the defects produced in the product are waste of resources.
5. Too many inspection processes to secure the quality more than the demands of customers do not add any value to the system.

Muda is not entirely an independent process, it coexists Muri and Mura. Let’s discuss further.

What is mura

Mura means unevenness. Following are the examples of mura in a manufacturing industry.

• unevenness in the reception of raw material quantity
• variation of order from the customer
• unevenness in the scheduling of work centers
• uneven production output due to variation in the process

What is muri

Muri means overburden. Following are the examples of muri.

• Running a machine more than its designed speed, for producing more products than standard output.
• Assigning work to an employee more than what he can do.

How Muda, Mura and Muri are interlinked to each other

Let’s start with Mura, unevenness. Because, its the root cause of most of the wastes.

In our first examples listed in the section ‘what is mura’, raw material comes to factory unevenly. That means raw material do not reach the factory in a constant quantity, some times less than the demand.

So the work centers cannot produce the required quantity for meeting the demand. Also the machines or manpower will be idle due to raw material shortage. This idleness of machines or manpower can be classified into eighth waste, which comes in the category muda.

Due to this lost production, one day we might be forced to produce products beyond the standard capacity of machinery or workmen. This leads to overburden on equipment and workmen, which is muri.

More raw material should reach production floor than usual, which results in high inventory level, which again comes in the category muda.

Running machines beyond designed speed may leads to defects, which comes in the category muda. It may also leads to breakdown of machinery, which will leads to delay.

So, If Mura is present in the system, then definitely Muda and Muri is also present because unevenness lead to overburden. Similarly if Muri is ignored it can lead to sudden breakdown and this breakdown lead to waiting of inventory which is again associated with Muda.

Therefore all three are interlinked with each other.

Why it is Important to Eliminate Muda, Mura and Muri

We have seen that the existence of Muda, Mura and Muri in a manufacturing process, will leads wastes. These waste is equivalent to some money. So if we eliminate these waste, we will save some money and we can reduce the manufacturing cost. Hence we can fix a competitive price to our products.

Think about products produced by two different companies with different price and same quality. Whose product will you buy?

I will buy the product from manufacturer, who sells the product with lowest price.

I think you got the answer.

How to eliminate Muda, Mura and Muri

The answer to this question leads to the birth of lean manufacturing and its tools and techniques. Some of them I am listing here, and we have articles on those subjects.

• 5S
• Line balancing
• Value stream mapping
• Kaizen
• Layout
• Why Why analysis
• Bottleneck analysis
• Takt time
• Heijunka
• Kanban
• Poka yoke
• Just in time

The list is not limited to above, there are various Lean tools and techniques developed by companies to eliminate Muda, Mura and Muri.

5S helps to reduce motion and delay. Line balancing and bottleneck analysis helps to reduce delay. Value stream mapping helps identify all wastes.

Heijunka and Kanban helps to reduce mura. Good layout planning helps to reduce transportation. Kaizens generate solutions to eliminate waste.

Why Why analysis gives the root cause of an occurrence of a waste. Poka yoke eliminates occurance of defects. Just in time eliminates over production.

Thank you.

I am very thankful to Nalini Kumari for contributing to this article. She has contributed to the major portion of this article, especially all images in this article are her creativity.

If you know any subject that can be related to manufacturing industry or industrial engineering, you can earn some income by becoming article contributor of this website. For knowing more about it, please visit Join us page.

You don’t need to have any experience in article writing, just knowledge on the subject is needed.

Also you can know more about our team of article contributors by visiting the about us page.

About the article contributor

She is passionate about learning and growing in Quality management, Lean manufacturing, and the various other Industrial engineering topics. A passionate writer and an undergraduate from the Industrial and production Engineering domain, Nalini Kumari is one of the Author for our website whose knowledge and flair writing skills can hold the interest of readers. She is very clear with her words while writing which can be best seen from her work on the Juran Trilogy article.