Muda mura muri

Muda, mura and muri (3Ms of lean) are the pillars of fight with waste in production and services. They are important part of Toyota Production system and Lean manufacturing. They mean:

• Muda - actions that don't add value for the customer,
• Mura - unevenness or inconsistency in processes,
• Muri - overburden of employees, machines, processes

Muda, mura and muri are the example of hidden factory. The organization performs many actions that are not paid by the customer. They are loss for the company. Implementation of lean thinking leads to removal of hidden factory.

Muda

Muda is the waste created by actions that don't add value to the customer. There is a list of 7 wastes in production and another list for services.

Modern approach to business is not about product only, but about product extended by additional service and support. Therefore, modern enterprise should take into account both lists of wastes.

7 wastes of production

The wastes are described in detail in another article 7 wastes of lean.

1. Overproduction
2. Inventory
3. Defects
4. Motion
5. Over-processing
6. Waiting
7. Transportation

7 wastes of services

The wastes are described in detail in another article 7 wastes of services.

1. Delays
2. Duplication
3. Motion
4. Unclear communication
5. Inventory
6. Errors
7. Opportunity lost

Mura

Do you have to "make the numbers" at the end of reporting period? In order to improve results, salesmen decrease prices. Therefore, production has to be increased. But at the beginning of new period it almost stops. This increases overburden (muri) and risk of wastes (muda). As you can see, all three of them are connected. The enterprise has to maintain higher capacity than necessary in order to deal with unevenness. After weeks of increased work, sometimes on three shifts, including Saturdays and Sundays, come weeks of waiting for next order. Workers forget their skills and at the beginning of new period increased number of defects is detected.

Reducing mura using heijunka and just in time

The mura can be reduced using proper organization of production. One of the methods that help reduce mura is Heijunka (production levelling). Using prediction models it is possible to forecast the demand and find optimum level of production. This eliminates the Forrester effect, which is one of mura causes.

It is important to state, that reduction of mura can appear not fully compatible with TPS or Lean manufacturing, as implementation of Heijunka requires increased finished goods inventory. The optimization of whole enterprise can require sub-optimization of its parts. It shouldn't be a surprise.

Reduction of mura using just in time is not possible, as JIT leads to reduction of inventory at a cost of production unevenness. The top management has to decide which is more important.

Muri

The overburden is a cause of many quality problems, as well as safety threats. The muri is created by mura or low efficiency of management. The overburden is caused by:

• performing work that workers are not trained in,
• wrong layout of workplace,
• cluttered workplace,
• unclear communication,
• wrong communication routes,
• incorrect tools, equipment, inventory,
• mura
• wrong maintenance
• low quality equipment
• unreliable process.

Examples of Muda mura muri

Muda:

• Overproduction – creating more than what is needed. For example, a manufacturing company producing more parts than required by the customer.

Mura:

• Unevenness – producing too much of a product in one area and not enough in another. For example, an assembly line having a bottleneck due to lack of resources in one area while having too much resources in another.

Muri:

• Overburden – pushing workers to work faster than they can handle. For example, having workers work long hours to meet production demands without taking into account the safety and health of the workers.

Advantages of Muda mura muri

Muda, mura and muri are the three Japanese words that form the foundation of Lean manufacturing. They are important elements of the Toyota Production System and help to support the ongoing fight against waste in production and services. The advantages of embracing Muda, mura and muri are numerous, as they include:

• Reduction in waste, which can lead to cost savings, increased efficiency and higher quality output.
• Improved customer satisfaction, due to shorter lead times, increased reliability and improved quality.
• Increased employee morale, as staff are better able to focus on value-added activities, are better supported by processes and are more likely to be able to work on meaningful projects.
• A culture of continuous improvement, as staff and leaders are more likely to be actively engaged in the process of identifying and eliminating waste.
• Improved collaboration between teams, as teams are encouraged to work together to identify and eliminate waste.
• Greater innovation and creativity, as staff are empowered and encouraged to come up with new and creative solutions to problems.

Limitations of Muda mura muri

Muda, mura and muri are the pillars of fight with waste in production and services, which are an important part of Toyota Production System and Lean Manufacturing. However, there are certain limitations of these 3Ms that should be taken into consideration. These include:

• Muda: This concept is limited by the fact that production processes are highly dependent on the environment, while Muda focuses on eliminating waste through repetition of tasks. Therefore, it is not applicable to non-repetitive processes.
• Mura: This concept is limited by the fact that it is difficult to achieve consistent and predictable results when dealing with a variety of production processes, as Mura focuses on achieving uniformity.
• Muri: This concept is limited by the fact that it is difficult to measure production processes, as Muri focuses on improving the efficiency of processes. Therefore, it is not applicable to processes with uncertain outcomes.

Other approaches related to Muda mura muri

Muda, Mura and Muri, also known as the 3Ms of Lean, are the pillars of waste reduction in production and services. They are integral parts of the Toyota Production System and Lean Manufacturing. In addition to the 3Ms, there are other approaches and concepts related to Lean and waste reduction, such as:

• Visualization: Visualization is a key element of Lean, as it enables workers to quickly identify waste and spot problems. Visualization involves the use of visuals, such as tables, charts and graphs, to help workers identify and address issues in the production process.
• Kaizen: Kaizen is a Japanese term that means “continuous improvement”. Kaizen is a systematic approach to problem solving which encourages workers to identify and address problems quickly and efficiently.
• Standardized Work: Standardized work is a term used to describe the process of documenting and standardizing the steps involved in a particular job. It is an important element of Lean, as it helps to ensure that the same quality of work is produced every time.
• Jidoka: Jidoka is a Japanese term meaning “automation with a human touch”. It is used to refer to a system of automated processes that can detect problems and alert workers to take action.

These are just a few of the approaches and concepts related to Lean and waste reduction. Together, they form the foundation of the Lean Manufacturing system, which is designed to help organizations reduce waste and improve efficiency.

Muda mura muri — recommended articles

Quality assurance — 7 wastes of lean — Lean manufacturing — Continuous improvement — 5S method — Internal failure costs — Toyota production system — Work cycle — 7 wastes of services

References

• Imai M., (1997) Gemba - Kaizen, A Commonsense, Low-Cost Approach to Management, McGraw Hill Companies, Inc., New York 1997
• Imai M., (1986) Kaizen (Ky' zen) The Key to Japan's Competitive Success, McGraw Hill, Inc., New York 1986
• Womack J.P., (2006) Mura, muri, muda?, Lean Enterprise Institute (PDF)

Author: Slawomir Wawak