FMEA Kick-Off Meeting - Calculating an RPN
Now, we'll take a look at an example of how to calculate an RPN in an FMEA meeting.
Your FMEA worksheet has been created and based on existing and previous failure info (from historical projects); you have identified all possible failure modes for every step in the process. You are now ready to have your first FMEA meeting and this meeting should have knowledgeable representatives present (at least one from each department involved). Involved departments will have failure modes directed to them for corrective action. If your department has no pending failure modes for action, you are very lucky indeed and can skip this meeting.
1. The first FMEA step in a new project is to complete the severity information.
For example: Failure mode is "missing component," technical information is that "heatsink HS1 is missing." The failure effect (or end user issue) is that "the unit overheats" or "user burns fingers" (not too typical this one, although a number of laptop manufacturers had to recall batteries due to risk of explosion, so it can happen). Obviously this is a critical error and is given the highest ranking 10 since injury is possible.
2. The next step is determining the occurrence frequency.
Continuing with the previous example, let us assume that this heatsink is manually soldered on, making the root cause a human error at two points in the process, rework area and inspection. How often does this occur? If less than 1% then assign 1 to it, making note of the fact that the issue is not fully removed from the process.
3. Finally, how easy is it to detect this problem?
As there are a number of possible steps where this failure can be detected (by automated or manual inspection after rework) and also during final audit, this particular failure can almost certainly be detected before shipment. We then assign 1 to it.
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