Types and Forms of Waste in Lean

The essence of Lean is to reduce waste and get more to satisfy customers. Sources of waste exist everywhere, and waste shows up in many different ways.

Types of waste

Three Ms describe the waste in Lean:

• muda: Waste; any activity that does not add value

  Type-1 muda: Non-value-added, but necessary for the system to function

  Type-2 muda: Non-value-added and unnecessary for the system to function; the first targets for elimination

• mura: Waste due to unevenness or variation

• muri: Waste caused by overstressing people, equipment, or systems

The seven forms of waste

Known also as the seven mudas or seven wastes, these forms of waste were identified by Taiichi Ohno, a pioneer of the Toyota Production System.

• Transportation: Is there unnecessary (non-value-added) movement of parts, materials, or information between processes?

• Waiting: Are people, parts, systems, or facilities idle, waiting for a work cycle to be completed?

• Overproduction: Are you producing sooner, faster, or in greater quantities than the customer is demanding?

• Defects: Does the process result in anything that the customer would deem unacceptable?

• Inventory: Do you have any raw materials, work-in-progress (WIP), or finished goods that are in excess or not having value added to them?

• Movement: Do you move materials, people, equipment, and goods unnecessarily or excessively within a processing step?

• Extra processing: Do you have work being performed beyond what is required to satisfy the customer standards or requirements?