Lean Or Six Sigma?

For more than 100 years, Lean Manufacturing has evolved from Frederick Taylor and Henry Ford to Edwards Deming, to  J. Womack and D. Jones with their 1966 publication of Lean Thinking (1996).

In Lean Thinking, Lean was defined as consisting of five key principles: “Precisely specify value by specific product, identify the value stream for each product, make value flow without interruptions, let customer pull value from the producer, and pursue perfection.”

Today there are numerous tools used for continuous improvement within and in support of a Lean process. Examples are 5S, standardized work, A3 problem solving, failure modes effects analysis, 5 Whys, Fishbone diagrams, root-cause analysis, Kaizen events, 7 wastes, and Total Productive Maintenance (TPM). The fundamental premise in all of these is continuous improvement at the plant-floor level: find the bottleneck, analyze for the six big losses (see chart), and then use small teams to identify and implement improvements.

The premise in all Lean tools is continuous improvement: find the bottleneck, analyze for the six big losses, identify, and implement improvements.

Six Sigma is also a group of tools and techniques that can be used to improve business performance. The main goal of Six Sigma is to minimize errors and improve consistency (reduce variation) in the manufacturing/production process and often to improve product quality. Six Sigma is typically done as a project with a specific goal. Statistically, a Six Sigma process runs at 3.4 defects per million or 99.99966% process capability (defect free). This scientific process typically uses a DMAIC approach: Define, Measure, Analyze, Improve, and Control. Some of the tools are similar to Lean such as FMEA, Value Stream Mapping, Root Cause Analysis, and Poka-yoke (mistake proofing).

“After years of steady gains, Lean has now achieved a clear and dominant standing over Six Sigma as the leading force in corporate continuous improvement,” according to the latest study of almost 3,500 recent job postings reviewed by The Avery Point Group, Alpharetta, GA (leansigmarecruiter.com), a global executive search and recruiting firm for Lean and Six Sigma talent.

I’ve worked with Six Sigma black belts to solve tough production/product challenges. These issues could not have been solved without the required statistical analysis using a rigid Six Sigma methodology. However, I would want my facility to be mostly focused on the simpler Lean principles developing an entire plant full of problem solvers. Lean and Six Sigma are around to stay, but the future will continue to trend toward engaging more of the workforce using Lean best practices. EP

Based in Knoxville, Dr. Klaus M. Blache is director of the Reliability & Maintainability Center at the Univ. of Tennessee, and a research professor in the College of Engineering. Contact him at kblache@utk.edu.