Michel Baudin, a Lean consultant whose blog I follow with great interest, published an extremely interesting article that compares different approaches for process improvement in manufacturing organizations.

I have read a lot of attempts by consultants and academics to explain how two or three of these approaches a complementary. Baudin’s opinion is as below:

They really are competitive brands put out by consultants vying for clients in overlapping markets. And they are so different is scope and track record that they do not belong together in a list.

How different are they? Let’s briefly describe TQM, TOC, 6 Sigma, and Lean.

TQM – Total Quality Management

It was very popular in the US in the 1980s and 1990s, and has inspired the ISO900x series of standards. Many  professionals in the “quality” field are still attached to this approach. But it is generally no longer considered the most effective strategy by business leaders.

In Baudin’s article, TQM is presented as a “watered-down version of the Japanese TQC”, itself a valuable approach:

By 1975, all the major manufacturing companies in Japan had received the Deming prize for implementing TQC, and all that could be gained from it was incorporated in their practices.

Theory of Constraints

The TOC’s father was Eli Goldratt, the author of the excellent book The Goal.

He was initially selling a scheduling software that did not bring the desired results in many of its applications. He then tried to put together a system for improving production efficiency that he called “theory of constraints”.

Baudin’s comments on TOC:

If phrased as the need for organizations to focus on what is preventing or limiting their ability to reach goals, it is obvious and, at this level of generality, not markedly different from eliminating waste or focusing on “value adding” activities. When you consider specifics, such as production operations, it reduces to an execution methodology called drum-buffer-rope, which still ignores the elephants in the manufacturing room, including how to design factories, lay out production lines, engineer work stations, and apply human resources.

I wouldn’t be as tough with TOC. I simply view it as part of a Lean implementation. Lean is much wider in scope. As Bill Waddel, another Lean consultant, wrote:

Just because you are pursuing lean, rather than an “overarching TOC-based solution”, you cannot afford to ignore the critical importance of constraint identification and optimization.

Interestingly, Goldratt shared the same distrust toward analytical accounting metrics as Lean practitioners. And the same tendency to rely on smaller, non-automated machines.

Six Sigma

This approach was very popular in the 1990s and 2000s. But it was recently abandoned by GE, even though it was one of the few big initiatives pushed by Jack Welch, and other early enthusiasts.

Six Sigma was developed in Motorola’s semiconductor division. It is not very applicable to other industries for a simple reason:

In the semiconductor industry, you first develop a process to make chips, and then design products to make by this process, which is not the way most other industries work.

Six Sigma’s stated objective is to keep opportunities for defects down to 3.4 per million. If there are 100 independent opportunities for mistakes in a process, the ratio of defect-free products goes to ❨1 – 3.4×10-6❩100= 99.97%.

Baudin’s comment:

It works out to .03% = 300ppm of defectives, a level of quality that the auto parts industry, among others, have long exceeded, by non-statistical methods. I know of one case of a Toyota supplier that had produced more than 1 million units without a single defective by using Toyota’s Jikotei Kanketsu (JKK) and Change Point Management (CPM).

Six Sigma seems to work very well for some high-tech products, but not to be the best approach in other industries. It was a huge success in marketing terms, though. The green- and black-belt certification system has been widely popular.

Lean Enterprise system

Lean is not a method. There are no “10 steps to get lean”. It is not easy to implement, mainly for two reasons:

• It is a “strategic weapon”, as Art Byrne wrote. It needs a total commitment from the leaders of the company, as well as deep changes in thinking across the organization.
• It is based on the Toyota Production System, which was refined over decades. Outside of the car industry, and especially in non-manufacturing environments, companies need to understand it deeply and adapt it to their needs.

I wrote about Lean’s benefits here and here.

Lean Six Sigma

Some consultants say that the combination of Lean (for speed and the focus on eliminating waste) and Six Sigma (to bring processes under statistical control) is very powerful. But, in light of the limitations of Six Sigma as mentioned above, Baudin logically rejects this idea.

The most successful repackaging attempt is “Lean Six Sigma,” in which the technical content is entirely from Lean, with only the title of Black Belt remaining for implementers.

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Michel Baudin is a Lean consultant, and naturally considers Lean a much more effective improvement approach. And I strongly agree with him.

What do you think?