While they’re often used together Lean and Six Sigma are fairly different approaches to organizational improvement. Six Sigma is a highly effective approach for reducing variation in processes with narrow bands of tolerances, such as those found in engineering, biological, and chemical environments. Examples of relevant applications include ballistics, percent water in oil extracted from the group, level of magnetism for magnetic devices, amount of fluid dispensed through an intravenous line, electrical conductivity, etc. Six Sigma is often a months-long approach to refining a process and many organizations require the guarantee of a significant return on investment before a Six Sigma project can be launched. Six Sigma is best described as a process improvement methodology for specific environments.
Lean is a business management philosophy that applies to organizations of all sizes and types, in all industries. While the basic goal is waste reduction, it is the means by which waste is reduced that moves Lean into the broader category of general business management. Very few U.S. companies have truly embraced Lean the way in which it is intended and the way in which it generates the greatest results. Lean’s premise is that an organization should eliminate all expenditures and effort that its customers do not value. When value stream mapping is used as a strategic improvement planning tool, it typically reveals that 30-80% of an organizations effort is pure waste. Through a structured improvement process that involves the entire workforce, organizations slowly transform themselves into Lean Enterprises, able to thrive during strong economic times and survive economic downturns.