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I work at a small automotive manufacturing company (approximately 100 employees at my division) and have been working in the quality department for a couple of years now. Our calibration program is pretty weak and we are attempting to rebuild and strengthen the system.
While working on this project I am strugling with the concept of "calibrating against certified equipment having a known valid relationship to nationally recognized standards". I am not sure if a gage has to be calibrated directly to our highest in-house standard, or if calibrating a gage to this standard and then using this gage to calibrate another measuring instrument is acceptable or not.
A typical example is as follows. I was informed by someone that our gage pin set(pins in increments of .001") has to be sent out to an outside lab for calibration and thereby recieve a certification that is traceable to NIST. The only gaging that we currently do this for is our highest in-house standard, a set of gage blocks. These blocks are used to maintain traceability to NIST with our in-house calibrations. The pin set is a shop floor working set that is used for a variety of tasks, i.e. measuring a depth over a radius broached feature with OD Mics., go/no-go diameters of holes and slots, etc. My question is this. Is it acceptable practice to calibrate a set of .0001" OD mics. against our highest level gage block set, and then calibrate the pin set with the micrometers? I understand that the measuring accuracy of what I am using the pins for will probably impact the justification for this so what if instead I carried out the same procedure but instead of using an OD micrometer, I used a laser micrometer with an accuracy of +/- .00002"?
I am trying to justify what are acceptable calibration methods to industry standards at a level that will ensure our gages will adequately provide quality product at the most economical cost. Please help.
While working on this project I am strugling with the concept of "calibrating against certified equipment having a known valid relationship to nationally recognized standards". I am not sure if a gage has to be calibrated directly to our highest in-house standard, or if calibrating a gage to this standard and then using this gage to calibrate another measuring instrument is acceptable or not.
A typical example is as follows. I was informed by someone that our gage pin set(pins in increments of .001") has to be sent out to an outside lab for calibration and thereby recieve a certification that is traceable to NIST. The only gaging that we currently do this for is our highest in-house standard, a set of gage blocks. These blocks are used to maintain traceability to NIST with our in-house calibrations. The pin set is a shop floor working set that is used for a variety of tasks, i.e. measuring a depth over a radius broached feature with OD Mics., go/no-go diameters of holes and slots, etc. My question is this. Is it acceptable practice to calibrate a set of .0001" OD mics. against our highest level gage block set, and then calibrate the pin set with the micrometers? I understand that the measuring accuracy of what I am using the pins for will probably impact the justification for this so what if instead I carried out the same procedure but instead of using an OD micrometer, I used a laser micrometer with an accuracy of +/- .00002"?
I am trying to justify what are acceptable calibration methods to industry standards at a level that will ensure our gages will adequately provide quality product at the most economical cost. Please help.