The real answer is it is both. And it is an output of
FMEA, but BOTH of them.
The design group conducts the
DFMEA and this will identify special characteristics based on the function of the product. ALL of these a transferred to the
PFMEA and handled appropriately. If there are none, then none need to be created.
BUT ...
It is also totally appropriate that if when the manufacturing types are conducting the PFMEA they mark additional SC as they see fit. These are not determined by "critical to function" but rather by "key to control the process." And they are free to add any that help them manufacture better, but there is no requirement that they create some just to have some ...
How about some examples? Sure - no problem.
Example 1: Almost ANY molding process with a parting line. In any molding process, you want to ensure the halves of the mold are brought together in the same way each and every time. There may be a pair of surfaces that cross the parting line that are very easy to measure with calipers or some automated transducer that have nothing to do with the design or functionality. This is a good candidate for a manufacturing SC because it is a) easy to measure and b) describes a key part of the process that needs control and monitoring.
Example 2: Any sort of induction or coil based mechatronix device. After you wind your coil you may want to do a simple continuity check (to make sure your wires are varnished) OR a B-field magnetic check. Point is - some check on the coil itself that makes sure it's healthy before all the other components are added to the circuit (which may make it impossible to diagnose the coil alone).
Example 3: Some intermediate machining step. Let's say you are going to establish some datums and further on, you initial datums are removed. You may need to mark some intermediate features as SCs even if they are machined away at a later time. The goal here being cull scrap as soon as possible. If you don't, you machine it later. And running a bad part completely through a process is expensive.
If you have your auditor telling you that you MUST have them, the auditor is wrong. It's really a financial decision, honestly. What are you willing to do to NOT send bad parts?
If you say there are none in the manufacturing process, I would caution you to look again. In very few cases I have seen has there been no reason (primarily due to OEE reasons) to not have SOME in process monitoring done on things that don't directly connect to the final design.
