Continuous Improvement Firm (CIF):

Lean Manufacturing

3 Broad Types of Waste

Unreasonableness (Muri), Inconsistency (Mura), Waste Activities (Muda)

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"Only the last turn of a bolt tightens it the rest is just movement." ~ Shigeo Shingo


The Three Broad Types of Waste

The elimination of waste is the goal of Lean Production. Toyota defined three broad types of waste: muri,  mura and muda.

The Toyota Way: 14 Principles

The words muri, mura and muda are often used together and referred to as the three MU's in Japan. "Just as muda offers a handy handy checklist to start  Kaizen, the words mura and muri are used as a handy reminder to start Kaizen in a workplace (gemba). Mura means irregularity, and muri means strain. Anything strenuous or irregular indicates a problem. Furthermore, both mura and muri also constitute muda that needs to be eliminated," writes Masaaki Imai.1

Muri is all the unreasonable work that management imposes on workers and machines because of poor organization, such as carrying heavy weights, moving things around, dangerous tasks, even working significantly faster than usual. It is pushing a person or a machine beyond its natural limits. This may simply be asking a greater level of performance from a process than it can handle without taking shortcuts and informally modifying decision criteria. Muri also includes bad working conditions, and it will often push a resource to work harder than its natural limits.  Unreasonable work is almost always a cause of multiple variations. Lean focuses on the planning of processes to avoid muri and on the preparation and planning of the process, or what work can be avoided proactively by design.

Mura is the variation and inconsistency in quality and volume in both products and human conditions. Lean focuses on how the work design is implemented and the elimination of fluctuation at the scheduling or operations level, such as quality and volume.

Muda is the Japanese word for waste. It specifies it specifies any human activity, which absorbs resources, but does not directly add customer value. These non-value-adding activities and results are to be eliminated. Lean Manufacturing is, in its most basic form, the systematic elimination of 7 wastes overproduction, waiting, transportation, inventory, motion, over-processing, defective units and the implementation of the concepts of continuous flow and customer pull.

Muda is discovered after the process is in place and is dealt with reactively. It is seen through variation in output. It is the role of management to examine the muda in the processes and eliminate the deeper causes by considering the connections to the muri and mura of the system. The muda and mura inconsistencies must be fed back to the muri, or planning, stage for the next project.4




  1. Lean Manufacturing Overview, Factory Strategies Group LLC

  2. Lean Manufacturing That Works, Bill Carreira

  3. The Toyota Way, Jeffrey Liker

  4. Toyota Production System, Taiichi Ohno

  5. Lean Manufacturing, Wikipedia

  6. Kaizen, 25 PowerPoint slides by Factory Strategies Group LLC

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3 Basic Principles of Continuous Improvement

10 Kaikaku Commandments

14 TQM Slogans at Pentel, Japan

8 Rules for Quality Management

Key Features of Lean Production

Characteristics of Lean Manufacturing Systems