Nov 14 2011
Last Call! Manufacturing Data Mining and
Last Call! Manufacturing Data Mining and Beyond 6σ: 2 Webinars on 11/15-16/11 http://ow.ly/7sIFi, #lean, #datamining, #sixsigma
Six Sigma
Apr 22 2010
Lean is about simultaneously improving all dimensions of performance, including quality
This is in response to Mike Micklewright‘s question on Why Is Quality So Rarely Central In Lean?:
“I see so many internal Lean “experts” using “Lean” as a means to increase efficiencies and productivity, and therefore, reduce costs. They still do not see the connection to quality. They see quality and the reduction of variation in significant product characteristics as something that is outside of the Lean scope and something that should be handled by the quality folks independently of the lean effort. What a shame! If you agree with this observation, why does this exist and what can we do to change this perception?”
Following is my response:
Quality not central to Lean? Says who? Lean is about simultaneously improving all dimensions of performance, including quality. Quality professionals frequently miss this, because what they learned primarily addresses process capability issues that are central only in high technology, where, if your process is mature, your product is obsolete. This is the context where statistical approaches like Six Sigma make a difference.
Modern machine tools, on the other hand, can easily hold required tolerances, and most quality problems are not due to lack of process capability. They are instead due to discrete failure of the equipment or human error. The main issue with discrete equipment failures is to detect them quickly so that they affect few parts and can be diagnosed before their trail is cold. With one-piece flow, defects are detected immediately instead of being buried in WIP, and this is why conversion from batch production to one-piece flow typically yields large improvements in quality.
The next step, which Dennis alluded to, is having machines stop as soon as they start producing defectives, but this still leaves human error, and that is addressed by mistake-proofing. Beyond these approaches, there is also management to prevent the deterioration over time, and plan responses to potential new problems.
This is a hierarchy of approaches. Actual numbers vary, but, in orders of magnitude, statistical tools will get you from 30% defectives to 3%, one-piece flow to 0.3%, mistake-proofing to 15ppm, and I know of one case of a Toyota supplier achieving <1ppm on some parts.
By Michel Baudin • Management 0 • Tags: Lean, Mistake-Proofing, One-piece flow, Poka-Yoke, Process capability, Quality, Six Sigma
Dec 9 2011
Six Sigma R.I.P.
If you google Six Sigma, you get the impression that it is a going concern, with all sorts of organizations offering training and consulting on how to implement it. If you dig just a bit deeper, you run into a Business Week article from June 11, 2007 entitled Six Sigma: So Yesterday? It explained how the best known Six Sigma icons, like GE, 3M, Home Depot, or Motorola were “dialing it back.” Whatever this may mean, it is difficult to imagine ambitious employees in a company showing enthusiasm for a program that is being “dialed back.”
The same article attributes the following statement to GE’s former CEO Jack Welch about Six Sigma: “Even if the concept is applied in areas where perhaps it shouldn’t be, it’ll be worth it in the long run.” It makes you wonder how he would have liked to work in such an area, with management knowingly pressuring him to implement an irrelevant method.
Now that the Six Sigma craze is over, there is no much merit in criticizing it. Ever since I was first exposed to it in the 1990s, I have perceived it as a welcome update of the now 90-year-old tools of Statistical Process Control (SPC), useful in industries where, if your process is mature, your product is obsolete. This applies in semiconductors and other high-technology manufacturing sectors, but not in mature sectors like automotive.
It never struck me as having the potential to be a revolution in business or comparable in scope and impact to Lean. Saying so 10 years ago made many people angry but I did worse: I put in writing, in an article entitled Six Sigma and Lean Manufacturing that was published by the SME in a Six Sigma newsletter in July, 2002.
If you google Motorola +Six-Sigma, you learn that Motorola no longer teaches Six Sigma business improvement. Given that Motorola is where Six Sigma was invented, the equivalent would be for Toyota to dump Lean. Maybe it is time to dial down the Six Sigma training programs.
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By Michel Baudin • Management, Technology 40 • Tags: Lean, Management, Quality, Six Sigma