How to Integrate Six Sigma & Lean Manufacturing

Lean Six Sigma improves every process in manufacturing, not just those that create product.

Lean and Six Sigma are very different methods for continuous improvement in a manufacturing organization. Lean targets processes, eliminating all forms of waste; Six Sigma eliminates all forms of variation (and in turn, eliminates defects). Lean is the more speedy of the two, Six Sigma the more methodical. But companies like Xerox and Caterpillar have successfully integrated the two processes, proving they are complementary, not contradictory. The combined practice is known as Lean Six Sigma, or LSS.

Instructions

1. Commit to implementing both Lean and Six Sigma practices where each practice works best. The US Army describes the need for a fusion of both practices, "Lean cannot bring a process under statistical control; Six Sigma alone cannot dramatically improve process speed or reduce invested capital; both enable the reduction of the cost of complexity."

2. Seek training in LSS from a trusted organization, like Xerox Business Services, IBM Global Business Services, or the Lean Learning Center. As the Lean Learning Center describes it, LSS requires change at three levels of an organization besides the leadership level: the Company level (system wide), the Program level and the Project level.

   System-wide training begins with upper and middle management, who in turn, train the remainder of the work force. Caterpillar sought outside training for 4,200 of 72,000 employees worldwide, then had the 4,200 train the remainder in LSS.

3. Seek a program that offers Six Sigma certification for Green Belts and Black Belts. These are individuals who are trained to lead Six Sigma projects, using the process of DMAIC (an acronym for define/measure/analyze/improve/control). Lean involves employees in identifying opportunities for improvement, followed by quick implementation while a DMAIC project may take several months. However, the DMAIC process is better suited to identifying more complex challenges, for example, unidentified causes of product or process defects.

4. Identify value streams. This is a Lean practice, not a Six Sigma practice. The value stream is the direct line to the customer or the customer's customer, wherein the manufacturer adds value. This includes receipt of materials from vendors, movement on the shop floor, production work stations, outbound shipping and so on.

   Xerox used LSS to streamline its patent filing process from 493 to 167 days, and has saved $400,000 in labor by eliminating two unnecessary steps in patent review. Caterpillar claims to have used LSS to "systematically de-bottleneck" its production process, which reduced lead times by 50 percent.

5. Train line-level workers in Lean principles, rather than the more complex Six Sigma, and seek their input about potential improvements. Lean involves employees at all levels, especially those who perform the work, in identifying areas for improvement. Typically, the employees look for waste in any process. Waste comes in seven types, according to the Lean Learning Center: overproduction; waiting; inventory; over-processing; motion; transportation and defects.

References

• U.S. Army: Lean Six Sigma
• Lean Learning Center: Lean Six Sigma
• "Driving Operational Innovation Using Lean Six Sigma;" IBM Global Business Services; 2007
• "Lean Six Sigma and the Quest for Continuous Improvement." Xerox Corporation, 2009
• Lean Learning Center: Lean Lingo Primer