Oftentimes a cause on a fishbone diagram is really a symptom of a larger, underlying root cause.
For example, tool wear might be noted as the reason for an out-of-specification condition on a stamped part. The obvious action would be to repair or replace the die.
However, the next logical question should be, “Why didn’t we catch this die wear and correct it sooner?” In cases like this, a more in-depth analysis and corrective action are needed, and the attached root cause analysis template provides a great format for doing so.
Completing the Root Cause Analysis Template
Note that this document includes three 5-Why paths to reach three causes. Only one path is necessary, but two other paths are provided in the event other systems or processes failed and need to be investigated (i.e., “Why wasn’t this problem caught in inspection?”)
Once the problem description and general information are completed at the top of the form, proceed to complete the root cause analysis process as follows –
|1||The idea of this exercise is to keep asking “Why?” until the root cause is reached. The first “Why?” goes in column 1 (see example below).|
|2,3||Follow the path of “Why’s” from left to right until an actionable root cause is reached – this is the cause that will be addressed in columns (4) and (5). It’s actually rare to reach an actionable 5th “Why?.” 3 or 4 Why’s is much more common.|
|4||Note the corrective action plan and owner assigned.|
|5||Ask the corrective action owner for a commitment date for implementation, and note it in this column.|
Here is an example of the above template, completed with the tool-wear problem mentioned above.
There are two root-cause paths that are followed in this example –
- The primary root cause of the out-of-specification condition (poorly managed tooling wear program)
- A contributing factor: why wasn’t the problem caught during the inspection process (quality system deficiency)?
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.
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