Lean Manufacturing, Chicken Knife. Six Sigma, Cow Knife.

I learned a new Chinese expression this week from a Six Sigma Master Black Belt from Taiwan. We were discussing how Lean manufacturing and Six Sigma fit together, and how sometimes there can be misunderstandings and conflicts between the two.
The expression in Chinese translates as “using a cow knife to kill a chicken” and sums up the reason we say Lean manufacturing should most often be implemented before Six Sigma.
Most of the problems visible as the 7 wastes of production in a traditional manufacturer can be solved through Lean manufacturing implementation. Lean manufacturing offers many quick and practical solutions to problems in the factory. These changes can be made with minimal training by anyone who is willing to get their hands dirty.
As valuable as Six Sigma is, when used to as a multi-week project to solve a quality problem that could be spotted through hours of direct process observation and a few days of implementing pokayoke, Standard Work, and visual controls (all of which are primarily Lean manufacturing tools) this is an example of “using a cow knife to kill a chicken”.
Six Sigma is an essential complement to Lean manufacturing because sometimes the root cause of the problem is not visible, or the process parameters can not be observed directly. A Six Sigma approach is the surer method to solve these problems. In these case the chicken knife will not suffice to kill the cow.
The most important thing in doing kaizen is to understand what type of problem you are trying to solve, what the true root cause of the problem is, and having access to the tools that will solve the problem most effectively.

2 Comments

  1. Thomas

    August 2, 2006 - 8:57 am

    Good analogy. Another one I like is that 6Sigma is a Scanning Electron Microscope, and Lean is a good magnifying glass. It is good to have the SEM handy, but the majority of the improvement work will be done with the magnifying glass.

  2. Michel Baudin

    August 20, 2006 - 9:02 pm

    I think you have the sequence backwards. Six Sigma solves process capability problems. If your processes are mature, as, for example, in an auto industry machine shop, you don’t have process capability problems, and you have no need for Six Sigma. On the other hand, Lean Manufacturing works.
    If your processes are immature, as is chronically the case in high-technology industries, then you need Six Sigma to establish process capability and you can’t apply Lean Manufacturing until you have succeeded.
    In semiconductors, for example, if your processes are mature, your products are obsolete. As a consequence, industry leaders are always trying to produce in high volume with unstable processes. Once they have succeeded, using tools like Six Sigma, they have to do it all over again with the next generation of technology. And this is an environment where the tools of Lean Manufacturing don’t work.