Re: IQ, OQ, PQ compared to PPAP
PPAP & IQ OQ PQ are quite different, I'm not sure if a direct comparison can me made. IQ OQ PQ validates a process, typically this is individual processes, although it is sometimes used as a basis to validate full manufacturing routes.
IQ OQ PQ doesn't call for process capability or gauge studies specifically but there's no particular reason why they can't be included. (Gauge studies may be required in IQ for new gauging methods)
IQ OQ PQ, as your may have inferred from the name comes in three stages:
IQ - installation qualification
OQ - operational qualification and
PQ - performance qualification
IQ - verify the equipment is installed correctly, training, utilities, could include DoE for new unfamiliar processes, SOPs, risk analysis, preliminary control plans etc etc
OQ - testing "worst case parameters" - basically define the worst case settings for the particular process and ensure it still gives acceptable results - i.e. for an ultrasonic cleaner it could be lowest temperature, lowest frequency and lowest solvent concentration.
PQ - this ensures the process is repeatable - to do this you would have to define a statistically relevant number of production runs of typical batch / lot sizes. Although often I used the "three batch rule" - running 3 batches of the largest & smallest parts in a product range. The 3 batch rule isn't recognised offically anywhere as far as I know. This is all done under normal manufacturing conditions - i.e. no special inspection - everything as it would be in full production.
I posted the GHTF (Global Harmonisation Taskforce validation guidance the other day .