If you want to get technical, this topic is better dealt with by others since it is a quality matter rather than dimensional metrology where I hide out. But, disputes go on every day over measurements and sometimes resolving them can be quite challenging—when possible.
Establishing calibration intervals for gages and instruments is a tricky business, particularly if you’re starting from scratch. Calibration data, knowledge of metrology and experience come into play in this game so before we begin, let’s look at the goal we hope to achieve.
I offered some comments that relate to gaging problems in the last column but thought it would be worth giving measuring instruments the same treatment.
Nothing could be simpler than fixed limit gages which explains why they remain so popular. But nothing so simple can remain so when humans are involved.
As I lied once before on these pages, I tend to avoid getting political in these columns with the exception of the occasional cheap generic shot. But since this is the first column of the new year, it’s that time again when the past year is reviewed and the number crunching begins.
We are frequently asked to quote on gage blocks made to non-standard dimensions. Requests like this leads to a number of questions, the first question being why they are needed in the first place.
One would think that when you get your thread ring gages calibrated and there are no red flags raised by the reported data you’re good to go. Unfortunately, this sea of tranquility can end up drowning you if you have misinterpreted the reports—something that happens when disputes arise.
Sometimes all the usual steps taken to resolve measurement disputes still don’t point to a culprit you can deal with. But one certainty always remains: Your customer insists their gages are right so the problem must be due to your gages.
We frequently calibrate gages and instruments in the dimensional field for labs that primarily deal with electronic or other disciplines. This occurs when their customers try to cut corners by adding one or more dimensional items onto an order they have received for their normal work.
Too often users of precision measuring instruments and gages end up with the wrong equipment and don’t find out until it’s too late. ‘Too late’ means after rejects are detected by in-house measurements or in worst case scenarios, by their customer.