Re:Tesla’s New Car Smell
by gumby on Monday October 16, 2017 @07:53PM
(#15487619)
You need both; they serve different functions. QA is choosing to use flame-retardant material; QC is installing a fire alarm.
QA addresses your process, from repeatability (e.g. ISO9000 in the cases where it makes sense -- less often than it is used, but sometimes it's crucial), incoming materials inspection, choosing processes that error in directions you want (should you mill material away from a billet, potentially taking not enough, or cast and potentially have the part shrink? Some systems can handle a too-small part better than a too-big one; other systems are the opposite) etc.
QC can be thought of output validation (i.e. testing, which is a lot of it): are my products of the necessary quality/within spec etc? Sometimes you can do 100% inspection, sometimes you have to use statistical methods (there are whole ISO specs devoted to nothing but sampling algorithms).
If you are not clear in your mind about the differences, the jargon can confuse you more (e.g. incoming materials inspection is sometimes referred to as "incoming QC"). But from this you can see why you "can't test your way into quality": the tests happen too late in the process.
QA addresses your process, from repeatability (e.g. ISO9000 in the cases where it makes sense -- less often than it is used, but sometimes it's crucial), incoming materials inspection, choosing processes that error in directions you want (should you mill material away from a billet, potentially taking not enough, or cast and potentially have the part shrink? Some systems can handle a too-small part better than a too-big one; other systems are the opposite) etc.
QC can be thought of output validation (i.e. testing, which is a lot of it): are my products of the necessary quality/within spec etc? Sometimes you can do 100% inspection, sometimes you have to use statistical methods (there are whole ISO specs devoted to nothing but sampling algorithms).
If you are not clear in your mind about the differences, the jargon can confuse you more (e.g. incoming materials inspection is sometimes referred to as "incoming QC"). But from this you can see why you "can't test your way into quality": the tests happen too late in the process.