This post will be included in the three ones dedicated to the Problem solving analysis introduction, dividing the problem solving in three phases: problem description, root cause analysis and action plan.
Firstly, do not forget that for understanding the root causes there must be a good definition of the problem, (see post Introduction to Problem Solving part I: Grasp the situation).
The first recommendation is to Build a team. I always recommend to reject answers to quality issues done only by quality department. It is not only a matter of ownership of the problem but also it is about involvement the affected people and experts to give their point of view. Ask operators, no one knows better the processes than operators.
Create a team, bring them to a close room and you will be surprised about their motivation. Start with a Brainstorming about possible root causes. It these phase of the problem solving methodologies it is very important to handle the group, motivate them, interact, make them participate, and the most important rule, at this stage never discard any idea !!
Once the brainstorming is finished group the ideas into the 6M (Material, measurements, machines, methods, Milieu (environment), manpower) based on Ishikawa, also sometimes also called Fishbone diagram. That gives a good overview of the weakest points in your company for that problem and possible areas of improvement.
Now comes the difficult part, how to discard possible root causes in the analysis and concentrate in some for further analysis. There must be a technical reason or a huge QA control that cannot avoid this to happen. But if one is doubtful, consider that in future analysis. Once chosen the most reasonable root causes, start the 5 Why’s methodology.
The 5Why’s methodology, helps one to come to the real root cause just asking why it happened. It ends when no more why can be asked. Normally all root causes come in less than 5 whys, but it can be extended. in Here it is a common failure to make a confusion between cause-effect, the parts are not dimensionally correct is a effect because i.e. machine parameters were wrong. Important also in this methodology is to use the because and come back from first root to the beginning. If something does not match it is because the methodology was not well driven.
Finally organize quickly the root causes (you will see some repeat themselves over the analysis) and Voila! you can just start defining actions (next post). Just a reminder: It is important that Ishikawa and 5Whys go together do not skip any of them.
In my opinion the root cause analysis is the most important part of the problem solving. I realized that most of the companies do not analyse deeply and it can become a repetitive problem for the company.
Post by miguelbrinesconsulting.com