Document Critical Paths
Process Flow Chart
Define All Critical / Special Characteristics
This diagram illustrates several critical paths in the documentation. I again want to stress that these documents may all be started at the same time and, in fact, typically are. However, the PFMEA cannot be signed off on as complete until the 3 input sources are completed. The control plan cannot be signed off on until the PFMEA is complete. The reason the control plan cannot be signed off on as it cannot be complete until the PFMEA contains all known possible issues.
Remember that the control plan will not necessarily contain every item from the PFMEA. That is in part the function of the process FMEA - to determine what ‘should’ or ‘must’ be controlled. It is a risk analysis.
At times this can become confusing because, for example, design validation may provide evidence that an issue not previously considered ‘should’ be addressed in the DFMEA and/or the PFMEA. Often by the time the design validation is started the DFMEA has been ‘finished’.
Process validation may in the same way reveal something which should be on the process FMEA (and probably on the control plan as well). As you can see, everything is not always consecutive and simple.
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