While this is "foolproof" it may be more than necessary. It is best to do a little analysis first. it is quite possible to have an instrument out of calibration and still be sure that all material shipped is conforming. As an example, suppose we have a characteristic of nominal 1.00 +/-.01. It is checked with an instrument with a gage tolerance of .001. When the instrument is checked at calibration, it is found to be at .0015 above nominal, out of calibration. A review of inspection records shows that the results recorded for units checked with the instrument are all in the range 0.995-1.004. If we allow for the inaccuracy of the gage, the range would have been 0.9965-1.0055, well within spec limits. The gage should of course be corrected, and steps taken on the calibration frequency, but as no non-conforming product has shipped, it is NOT necessary to inform the customer.
Geoff Withnell
Geoff Withnell

It's of prime importance to know how much out of specification the equipment is, and then to compare it to the product specification! All of the procedure posted could well be a total waste of time......
