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Lean Six Sigma

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City of Tyler Lean Sigma LogoLean Six Sigma is a strategic business methodology that combines two powerful methodologies that focus on customer satisfaction, cost, quality, process speed, and the elimination of waste and variation in the process. The two methodologies that are used are Lean Manufacturing and Six Sigma.

Lean Manufacturing

Infographic: 7 WastesLean Manufacturing is based on the Toyota Production System. The Toyota Production System was developed and refined by Taiichi Ono shortly after World War II. It is said that Taiichi Ono traveled the United States observing and learning from the auto manufacturers. Taiichi Ono has been said to contribute his development of the Toyota Production System based on concepts outline by Henry Ford in his book Today and Tomorrow. Lean Manufacturing focuses on the elimination of waste in the process. The elimination of waste allows the organization to provide a faster service while preserving value in the process. The seven wastes identified in Lean Manufacturing are:

  1. Transportation
  2. Inventory
  3. Motion
  4. Waiting
  5. Over-processing
  6. Over-production
  7. Defect

Six Sigma

Six Sigma is based on the methodology that was developed by Motorola in 1980s. Dr. Mikel Harry and Bill Smith helped to refine and develop Six Sigma into what we know it as today. Six Sigma goal is reduce variation that exists in a process. When processes achieve six sigma levels they are delivering 3.4 defects per million opportunities (DPMO). Most processes operate between three and four sigma levels (see chart below). Six Sigma uses a five phase process to identify and eliminate variation in a process:

  1. Define
  2. Measure
  3. Analyze
  4. Improve
  5. Control
Sigma Level DPMO % Defective % Yield
1 691,462 69% 31%
2 308,538 31% 69%
3 66,807 6.7% 93.3%
4 6,210 .62% 99.38%
5 233 .023% 99.977%
6 3.4 .00034% 99.99966%