"We don't need anything as advanced as Six Sigma. We can solve most of our problems using simple problem solving tools."
No disagreement there. Most of your problems are going to be straightforward. But some problems count a lot more than others. Much more. When ranked by cost, problems follow the familiar pareto distribution. You will find that the top ten problems in your factory are worth as much as the next 50, or numbers similar to that. This is the 80/20 rule. It's like an empirical law that shows up in many places.
There is a good reason why those problems are at the top of the pareto chart. These are the problems due to poor process capability. With poor capability, you will observe defect rates fluctuating daily between low and high fail rates. It can be visualized as the tail area of a distribution that wanders back and forth from day-to-day, month-to-month. Problem resolution in these cases will require knowledge of variance components analysis and variation reduction.
Infrequent problems, such as those caused by human error, don't show up in the top ranks. These issues tend to affect a low percentage of manufactured items.
Another category of failures are those where defects are bundled together. A failed batch or an entire shift of product. These failures are due to defects not being detected when and where they occur. This happens when we have infrequent sampling and also where sampling is downstream of where the defect is initiated. But these are often corrected and pretty fast because they come with sticker shock.
The problems at the top of your Pareto are those problems that are persistent and eat up a few percentage points of production. These problems will have been addressed before, perhaps a few times but unsuccessfully, and so they remain in place eating their share of your profits.
When your problems are process capability problems, the tools you need to understand, diagnose and correct them, don't come out of the bag of simple problem solving tools. These problems require a professional level of skill in problem solving.
There's a lot about problem solving that you need to know to be successful.
Learn advanced techniques for industrial problem solving.
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