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William A. Levinson, P.E.  Principal
570-824-1986
TheBoss at ct-yankee.com
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What has Six Sigma done for Motorola lately?

Six Sigma is primarily basic TQM

Six Sigma process capability



Six Sigma: What it can do and what it can't do

"What has Six Sigma done for Motorola lately?"
In contrast, Henry Ford's lean enterprise system, which Japan's Taiichi Ohno used as a model for the Toyota production system (TPS), did not let him down during bad economic times.  The reason was that Ford had a comprehensive lean manufacturing system that applied to every aspect of the business. Ford employees looked for ways to cut waste out of everything .
The Ford Motor Company sold 1.25 million cars during the 1920-1921 depression that followed the First World War and the 1918 influenza epidemic. This was about five times as many cars as the company sold during 1913-1914. That year was supposed to have been a "dull" year but Ford's company sold 33 percent more cars than it did in 1912-1913. (Levinson, 2002, Henry Ford's Lean Vision: Enduring Principles from the First Ford Motor Plant.)
The Six Sigma Black Belt is the only ASQ certification exam (the others were CQE, CRE, CQA, and CQM) for which I made no real effort to prepare, except for buying Thomas Pyzdek's Six Sigma handbook. (I recommend it highly if you plan to take the exam.) I relied on my degree and experience as an applied statistician, and I passed the exam the first time, in June 2001. My primary motivation was the fact that many companies are now scanning resumes for the phrase "Six Sigma." Levinson Productivity Systems is accordingly qualified to provide Black Belt-level services, but would actually like to offer something much better: a comprehensive and synergistic lean manufacturing program.
Levinson, "The Emperor's New Woes," in Quality Digest (May 2001) describes my perception of Six Sigma. Unlike the central figure of "The Emperor's New Clothes," the Six Sigma emperor is wearing clothing but he has paid several times its true value for the designer label.
Companies are afraid not to adopt Six Sigma and spend tens of thousands of dollars on training because they don't want to be seen as quality improvement throwbacks, out of step with the new quality fads. To stay current with the trend, they specify Black Belt certification as a job requirement, thus excluding quality practitioners who can't afford the expensive Six Sigma wardrobe. [This was before ASQ offered the alternative of a certification exam, which I did pass.] But nobody wants to look too closely at what the emperor is really wearing.
The article also contends that, if you have a degree in applied statistics, you are not going to learn much from a four-week Six Sigma training course. If you don't have a statistics degree (or at least courses in basic engineering statistics, design of experiments, and linear regression), you are not going to learn what you need to know in only four weeks, although you will learn what techniques are available and when they can be used. In other words, a Six Sigma course might equip you to work effectively with an industrial statistician, and it might also teach you something about project identification and project management. It will not make you into an industrial statistician or a lean manufacturing superhero.

There is nothing wrong with Six Sigma but there is nothing particularly innovative about it either.

  • Six Sigma's DMAIC (Design, Measure, Analyze, Improve, Control) cycle, even when expanded to RDMAICSI (Recognize, Define, Measure, Analyze, Improve, Control, Standardize, and Integrate) is basically the same idea as PDCA (Plan, Do, Check, Act).
    • The Ford Motor Company's TOPS-8D (Team Oriented Problem Solving, Eight Disciplines) is actually more versatile than RDMAICSI. It can be applied to a wider variety of projects. Although it was developed for corrective actions (i.e. reacting problems and instituting permanent preventive actions to keep them from recurring), it can be adapted easily to proactive improvement projects.
  • Standardization and best practice deployment are central features of Six Sigma. Standardization means making the improvement the official proceduce for the job (e.g. through the work instruction or operating instruction), and best practice deployment means making it the standard for every similar activity in the organization. Frederick Winslow Taylor and Henry Ford told us this more than three-quarters of a century ago.
    • "And whenever the new method is found to be markedly superior to the old, it should be adopted as the standard for the whole establishment" (Taylor, 1911, Principles of Scientific Management)
    • "An operation in our plant at Barcelona has to be carried through exactly as in Detroit— the benefit of our experience cannot be thrown away. A man on the assembly line at Detroit ought to be able to step into the assembly line at Oklahoma City or São Paulo, Brazil" (Henry Ford, 1926. Today and Tomorrow, p. 85, Productivity Press edition)
  • Mikel J. Harry and Richard Schroeder's Six Sigma, The Breakthrough Management Strategy Revolutionizing The World's Top Corporations (Doubleday, 1999) says, "Six Sigma, unlike other quality initiatives, needs to be understood and integrated at every level of the organization if long-term companywide improvements are to be made."
    • "Unlike other quality initiatives?" Armand V. Feigenbaum's Total Quality Control (ASQ Quality Press, 1985) warns that lip service from upper management is the "kiss of death" for any quality program.
    • "The writer would again insist that in no case should the managers of an establishment, the work of which is elaborate, undertake to change from the old to the new type unless the directors of the company fully understand and believe in the principles of scientific management and unless they appreciate all that is involved in making this change, particularly the time required, and unless they want scientific management greatly" (Taylor, 1911, The Principles of Scientific Management).
    • Harry and Schroeder can, however, easily be forgiven for their impression that Six Sigma is the first program to require this kind of commitment and understanding from all levels of the organization. Most people in the quality/ productivity business still believe that Japan (particularly Toyota) invented lean manufacturing. The Japanese actually learned it from Henry Ford's books, and Taiichi Ohno (father of the Toyota Production System) makes no secret of this.
Six Sigma is not a panacea
Motorola popularized the benefits of having six standard deviations between the process' nominal and each specification limit. If the process remains centered on the nominal, it has a Cpk (process capability index) of 2.0. This means a one part per billion nonconformance rate in each tail (above the upper specification and below the lower specification). Motorola allowed for a 1.5-sigma process shift-- which any decent statistical process control chart should detect very quickly, by the way-- which would make Cpk 1.5, and the nonconformance rate 3.4 ppm.

Six Sigma process capability: centered process
Six Sigma process capability with the process centered on its nominal (100). Cpk=2.0 and the nonconformance rate is 2 parts per billion.
Six Sigma process with 1.5 sigma shift in the mean
A Six Sigma process with a 1.5 sigma shift in the process mean. Cpk=1.5 and the nonconformance rate is 3.4 parts per million.

Again, there is nothing wrong with this, but there is nothing new about it either. Walter Shewhart and his contemporaries identified the issue of process capability decades ago, and Henry Ford was seeking ever-more-precise manufacturing equipment during the 1910s and 1920s! Ford, in fact, had to hire Carl Johannson (of the famous Jo blocks, or gage blocks) to get the precision measurement systems necessary to support his operation. During the 1920s, Ford boasted of owning Jo blocks with 1-microinch (25.4 nanometer) steps; these dimensions now come to mind in microelectronics manufacturing.

In summary, "Variation is the enemy" (we've known that for decades). Design for manufacture (DFM) includes consideration of the variation from the tools that will actually have to make the product. "Design for Six Sigma" is basically DFM, which also was a cornerstone of Henry Ford's manufacturing methods.


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