We have a part that gets CNC machined on a tombstone with 6 banks and each bank has 5 cavities (= 30 parts per tombstone/Fixture). We do have 4 Tombstones/Fixtures. We are planning to use those 4 Tombstones on 6 CNC machines. The machines are basically all the same (brand and model). Eventhough they are all the same, my point is that I think they are not (Age, Wear etc.). To my question: Does the Trial-run for PPAP have to be done on all 6 machines using all Tombstones or is it ok to run it on 2 or 3 machines only.