Here is a good post I pulled off a respected lean blog about how to sustain your improvements
Kaizen events can be tricky........on the surface they seem like more or less simple continuous improvement exercises but there are some key elements needed to make them successful and sustain: 1) Make sure that some of the people closest to the problem are involved in the event and that it is not just run by a bunch of outside 'experts'. This is how you get buy-in and ownership while at the same time building capability. 2) Make sure you use a sound, scientific problem solving method like Toyota's 4-Step and that at least one person is an expert in the execution of this. You don't need 6-Sigma on 95% of your problems, this 4-Step will work but the process needs to be diligently followed to get to root cause and achieve best results/sustain. 3) As an adjunct to #2, use real data to drive the problem solving and not opinion; this gets to root cause and removes emotion from the problem. With data, it is what it is. 4) Once we achieve a good result then who has the job to check that it is sustained? The worst thing we can do is make a change to a work environment, set a new standard, and it is so important that nobody ever comes back to check and see if it is working as intended or even being followed. Think of your Kaizen event as a big PDCA. I have done hundreds of Kaizen events with many clients around the world and this is the experience on which I base my advice. If you do these things, Kaizen WILL work and be sustained. Author - Andre DeMerchant.