Is Zero Defects Possible?

Sonu asks:

“Is zero defects possible? If so, what are the steps. We are dealing with around 300 parameters each having minimum 25 to 30 parameters to be met. We find it difficult to maintain zero defect for all parameters. Any thoughts???”

The first thing I would do is go to gemba. What does the machine, material, method and manpower (4M) for these processes look like? Then I would observe the process until a defect was created. It is always easier to catch the criminal in the act of committing the crime, rather than through detective work later. This in a nutshell is genchi genbutsu.
I would ask experienced people in the organization to share with me what they know about the problem, previous efforts to fix the problem, whether these were effective, and what is being tried currently to reduce defects. Their collective wisdom will inform and frame the issues.
These things would provide me with an intuitive sense of the products and processes.
The next step would be to review several types of Pareto charts of the types of defects, by part, parameter, by frequency and possibly other factors. The top items on the Pareto chart would be studied in further depth in terms of the 4Ms above, on the gemba, using a cause & effect diagram a.k.a. fishbone diagram.
At this point the combination of observed facts, intuition (what looks or sounds wrong, based on experience) and the data lead to the next steps. The next steps would most likely be a combination of things as simple as basic 5S (throwing out unnecessary items, putting all necessary items in the proper place for quick retrieval, and thoroughly cleaning to identify sources of contamination and filth), standardizing methods and procedures, checking whether our gages and measurement systems were capable, and possibly some design of experiment (DOE) type activity to see which parameters and conditions mattered the most.
I will leave the in-depth answer to this question of achieving zero defects to our friends Ron Pereira at the Lean Six Sigma Academy blog, Mike Wroblewski at Got Boondoggle?, and Rob Thompson at Quality Hero, each of whose Six Sigma chops far exceed my own.
Is zero defects possible? What is your experience? If you have sustained a zero defects process, what steps did you follow?

3 Comments

  1. John Hunter

    April 1, 2007 - 5:12 pm

    I do not think zero defects is a useful aim. If there were no items you classified as defects today have you reached an end point? I would say not. Plenty of waste can still be found to eliminate.
    I believe “defects” are really a matter of what is the current standard, if things improve to a point where past defects are eliminated, in most cases, things that were ignored previously will be considered defects. More on the limits of a Zero Defects strategy.
    I do believe the correct course of action is to continually improve (mentioned well in the post) and through those continual improvements it is possible to improve even a very complex system so that it meets all the expectations you have now. Often competing priorities mean that the resources redirected elsewhere prior to achieving that result. As the entire system improves the resources are less likely to be diverted to some new problem that is seen as more important and therefore you have a better chance of success (also the organization just gets better and better at improvement…).

  2. Ron

    April 1, 2007 - 6:23 pm

    I will post my two cents on this topic soon. Thanks for the idea Jon! I also look forward to what Mike and Rob have to say. Cheers.

  3. Pete Abilla

    April 1, 2007 - 7:56 pm

    Zero Defects — theoretically possible, yes; pragmatically possible, no. Why? It’s too expensive. Taguchi teaches us that preventative costs increases exponentially as defects approach zero.
    A firm’s goal is to attain economic profits, by maximizing revenue with the least amount of costs. It makes sense to have some defects, because it is practically not possible to have zero defects — it is too costly.
    My Take: This is not an either/or scenario. A firm ought to continually aim to reduce defects, making sure the customer experience is a good one, all the while watching the bottom-line and the top-line.