Lean manufacturing is a methodology to reduce waste in a manufacturing system without sacrificing productivity. Lean manufacturing’s main goal is to eliminate waste. The waste can be categorized into three categories- Mura, Muri and Muda which are commonly known as the 3Ms. In Lean Manufacturing, the 3Ms are considered as the culprit of inefficient processes. Increased value can be delivered to the customers by eliminating the wasteful processes.

MURA

Mura is the type of waste caused by inconsistency, fluctuation or unevenness in services and production. It is caused when the standards are not in place or when they are nor followed. For example, Mura is when the production process is measured on monthly output and the organization rushes to meet targets. Mura exists when there is uneven customer demand, inconsistent quality of supplies, irregular work scheduling, uneven distribution of work, etc. Process or production variation can lead to employees being overworked in the peak periods to meet the demand and then become idle when the demand drops. This can lead to inventory accumulation.

MURI

Muri causes overburden where unnecessary stress are caused to employees, processes and equipment’s leading to their breakdown. Muri is directly caused by Mura which is directly responsible for other failures such as lack of training, no defined or unclear procedures, unclear instructions, poor communication routes, unreasonable performance measurement and improper tools. It usually exists when the employees are made to work too hard or too fast in order to keep up with the demand, long working hours to compensate for the time lost, overloading of machines to get more yield, skipping equipment maintenance to reduce downtime, etc.

MUDA

Muda is any process or activity which does not add value to the product or service instead it just consumes resources without giving any useful output. It is a direct obstacle to flow. This just escalates the cost and increases the time taken to complete the task. It is essential to detect and eliminate Muda to reduce the cost, improve efficiency and effectiveness of the process which can lead to increased profit. The seven types of waste, namely- Transport, Inventory, Motion, Waiting, Over-processing, Overproduction and Defects are all recognized in Muda.

Mura, Muri and Muda

Mura, Muri and Muda are all interrelated to each other. Elimination of any one can affect the other two. When Mura is high, it increases the possibility of Muri and therefore leads to more Muda. By considering the impacts of Mura, Muri and Muda and by optimizing the production strategy, an efficient Lean Manufacturing system can be developed and implemented. Knowledge of the entire process is necessary before the introduction of any resolution for combatting it.

Various Lean tools, namely- Poke Yoke, SMED, 5S, Kanban, Just in Time (JIT) and Takt Time are useful in identification and removal of waste. Muda cannot be removed suddenly from the system otherwise it will again return. Therefore, Mura and Muri shall also be tackled to successfully eliminate the waste from the system. Mura, Muri and Muda are important factors to be taken into consideration while examining the business process and to decrease the inefficiencies. Elimination of all the 3Ms is necessary for creating a Lean process.