Process FMEA ( PFMEA )
A Process Failure Mode and Effects Analysis ( Process FMEA or PFMEA) is usually performed during the production planning stage of a product to determine how the manufacturing process(es) might fail, how likely such a failure would be (Occurrence), how serious it would be (Severity) and whether such a failure would be detected or prevented by the process controls before escaping to the customer (Detection).
There are two ‘levels’ of a Process FMEA (PFMEA).
An Assembly Process FMEA
This is performed on a the assembly process to assess the robustness of the assembly process.
A Manufacturing Process FMEA
This is done on the manufacturing process for all (or at least the most important) parts, to determine how robust the manufacturing process(es) for these parts will be. This may be done by suppliers if the parts are bought in.
How to do a Process FMEA
The process is similar to a brainstorm and should involve a multi-disciplinary team of ideally 4-8 people. The results are recorded on a special form (often an Excel Spreadsheet). The Severity, Occurrence and Detection are each scored from 1-10, and then these scores are combined into a Risk Priority Number (RPN), to give an overall ranking. Those with the highest RPN are identified for action to reduce the RPN. This may result in a modification to the process, which is why doing an FMEA should not be left too late. Processes controlling Significant & Critical Characteristics are those for which a Control Plan should probably be produced.
An template is shown below.
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