First, I would verify the accuracy of the gage itself by performing regular calibrations on the gage itself. Possible the appropriate ASTM can help you there. Once you know the gage is accurate, you will have documentation that the readings you are getting are accurate.
Second, you need to decide if you want to continue with the pass/fail system or switch to an absolute number system. If you choose pass/fail, your documented test instructions (Work Instructions) must contain a statement that a test response of “pass” indicates a reading of 3000 or greater. If this calibration statement is imbedded in the work instruction for the test itself, you will want to include that 3000 is the minimum acceptable reading allowed for a passing test.
Third, if you wish to change to a numeric system, simply record the readings you get stating that 3000 is your target reading. Give yourself a standard percent variance allowed by the ASTM method and when you fall outside that variance, you will have to recalibrate this piece of equipment plus follow your out of calibration requirements of your quality system. This applies as well for the second paragraph when you translate your readings to pass/fail.
This is somewhat simplified, so feel free to e-mail me back and I will give you instructions on how to get in touch with me.
Andy Brody, Quality Systems Manager
Marcus Paint Co.
Louisville, KY
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