Non-Conformance Report
Meaning ~ Documentation instrument detailing specific deviations from technical or contractual standards during production to control resolution paths and costs.
Instrument Error
Meaning
Measurement devices possess inherent limitations that skew data away from the absolute value. Instrument error is the difference between the actual physical property of an object and the value displayed by the measuring tool. It is a constant factor in every quality report and must be accounted for during the verification of specifications.
This discrepancy can be systematic, occurring in every reading, or random, caused by external interference.
Systematic Deviation
Fixed patterns of inaccuracy often result from poor calibration or wear on the tool’s contact surfaces. An instrument error of this type is predictable and can often be corrected by adding or subtracting a known offset from the result. If a scale always reads five grams heavy, the quality team must adjust the final weight report accordingly.
Neglecting this adjustment leads to batches being rejected for flaws that do not exist.
Calibration Frequency
Maintaining accuracy requires regular comparison against a known standard with a higher degree of precision. Reducing instrument error involves a strict schedule of laboratory checks and adjustments. Records of these calibrations are essential during a quality audit to prove that the factory’s tools are reliable.
A tool that has not been calibrated within its scheduled window is technically incapable of producing a valid pass result.
Result Adjustment
High precision manufacturing requires the calculation of uncertainty for every critical measurement. When instrument error is high relative to the allowed tolerance, the window for acceptable parts effectively shrinks. The manufacturer must produce parts even closer to the nominal value to ensure they pass the test.
This increases the difficulty of the job and often raises the price per unit.