The rule of thumb to have a good mix of kaizen team members from different areas is: 1/3rd of the people from the area or process targeted for kaizen, 1/3rd of the people from upstream or downstream processes (customers and suppliers) and 1/3rd from areas that are outside of or not strongly related to the process, such a finance person for a kaizen in the machine shop.

Sometimes kaizen team members ask "Why aren't there more people from the area on the kaizen team?" Or, "I don't know anything about this process, why was I chosen to be on the kaizen team?" These voices are heard when Lean Champions follow the rule of thumb for getting a good cross-functional mix of people on the kaizen team, without explaining the reasoning behind it.

Half of the purpose of kaizen events is education and half of the purpose is to get business results. By having people on the team that will not work in the area that is the target for kaizen, you are in effect educating people from other areas about kaizen and Lean. These people begin to spread the word, supporting communication and education.

People from outside of the process where the kaizen is done will bring outside perspectives. When you have people who know nothing about machines to a SMED event, it forces the process owners and experts to explain things in simple ways so that "even the finance guy" for instance, can understand. This helps group brainstorming.

The team members from outside the are also bring skills that might not be relevant to running the machine, but may be useful in other ways. Taking the "finance guy" example, he may be able to explain the financial impact of higher inventory turns and motivate the team towards SMED.

Team members from outside the area will not have pre-conceived notions or fixed ideas about how the process should be done. The less experienced team members may have some good common sense insights, without knowing all of the reasons why "it can't be done". They help by asking the questions about processes and assumptions people have and why things are the way they are. Ideally, this asking of questions (remember, there are no stupid questions) leads to the discovery of quick kill improvements.

Pulling in kaizen team members from other parts of the company (or even suppliers and customers) helps to keep from overburdening one department or work group. If the target of the Lean activity is the assembly line, you don't want to have the entire kaizen team be made up of assemblers. You will stop the line. You need knowledgeable process owners and experts, but you also need to borrow people from other areas. In return, you educate these people. And someday you may lend an assembler for a kaizen in the office.

Perhaps most important, this cross-functional team approach to kaizen enhances Value Stream awareness and thinking by making people aware of upstream & downstream relationships in business. Kaizen events should be breakthroughs, or ‘flow’ improvements rather than ‘point’ improvements that can be made within the department by everyone on a daily basis. The types of kaizen that improve flow and speed up the process of creating value for the customer are best done when the team looks at a series of processes as a section of a Value Stream.