Root cause analysis Rule #1
Rule #1 seems evident. This is probably because it IS evident. However it’s easy to find RCAs (root cause analysis) that violate this rule. Here is an example I’ve recently seen:
Our machine was not clean before we started the new batch. The operator that verified it did not see that one piece of the machine was dirty. He was new to the job and failed to follow the standard checklist properly. The root cause of our defect is “defective cleaning verification due to incomplete training”.
Yes, you got it. The “defective cleaning verification” cannot be the root cause because it happened AFTER the problem appeared. The machine was already dirty at that moment, which is the real problem. The adherence to the standards and the correct training of all operators are, of course, fundamental but it is not creating this issue.
Our quality systems are based in 3 types of actions: those that eliminate the problem, those that mitigate the effect of the problem and those make the problem visible. All of them are important, but only the first solve the root cause forever and improve the quality of our work. Without proper RCA, we will have the same issues again and again. This is why RCA is so important.