Lean methodology includes a set of principles and practices that aid the design, improvement, and management of processes. The Lean concept was preceded by many process improvement and quality improvement theorists, such as Frederick Taylor's scientific management and Frank Gilbreth's time and motion studies. The resulting Lean concept is credited to Taiichi Ohno's Toyota production system. The Toyota production system sought to improve efficiency by eliminating waste. The concept of waste used within Lean is somewhat broader than we may be used to when considering the term "waste." Lean "waste" includes not only raw waste, but also any activity that absorbs time and resources, but does not add value. Some Lean waste examples include:
- Re-work of any kind
- Unneeded process steps
- Unnecessary movement of materials or people
- Unnecessary wait time
- Creation of inventory or services that are not really needed by the customer
Muda is a Japanese term for "waste." Waste or muda is the enemy of Lean. Muda can be defined as any activity which consumes resources, yet creates no value. Examples of muda include mistakes that must be corrected, production of items no one wants to buy, processing steps that aren't actually necessary, and people standing idle because an upstream activity was not completed. Lean concepts include doing more with less human effort, equipment, time, and space, yet still coming much closer to providing exactly what the customer wants.