Oftentimes a given cause on a fishbone diagram is a symptom of a larger, underlying root cause. For example, tool wear might be noted on a fishbone diagram as contributing to an out-of-specification condition on a stamped part, and the obvious action would be to repair or replace the tool. However, the next logical question should be, “Why didn’t we catch this tool wear and correct it sooner?” In cases like this, a more in-depth analysis is needed to truly address the root cause, and the attached root cause analysis template provides a great format for doing so.
Completing the Root Cause Analysis Template
Once the problem description and general information are completed at the top of the form, proceed to complete the “5-Why” process as follows -
(1) The first “Why?” is noted below marker (1). This “Why?” should be the top reason behind the problem that is being addressed. For our tool-wear example, we might list the first “Why?” as, “The quarterly tooling review process is not functioning as designed.”
(2), (3) Follow the path of “Why’s” from left to right until an actionable root cause is reached. In this example, the second “Why?” in our tool-wear example might be, “The maintenance department is not making the tooling review process a priority.” The third “Why?” might be, “The management team does not get involved in quarterly tooling reviews, so the reviews are no longer a priority.” This third “Why?” provides us with an actionable root cause – set up quarterly report-outs for the management team on the tooling review process. Note that all five “Why’s” were not needed in this case.
(4), (5) Assign a corrective action to the root cause, noting the owner and due date.
The form provides two other “5-Why” paths in case they are needed. For example, we might create another path in our tool-wear situation that begins with, “Quality inspection results on the part were not reacted to.”
Using a root cause analysis template can help guide a team through the “5-Why” thought process, while at the same time documenting associated corrective actions. Keep this template handy the next time you need to create some structure around addressing a root cause.