Meaning
A property of a measurement result enables it to be related to a documented reference, usually a national or international standard, through an unbroken chain of comparisons. Establishing metrological traceability ensures that measurements taken on different equipment or in different laboratories are comparable and reliable. It is a fundamental requirement for quality management systems in high-tech manufacturing.
Calibration Chain
Each link in the comparison chain requires the calibration of a measuring instrument against a more accurate reference standard. This sequence must extend all the way back to the primary standards maintained by national metrology institutes. For metrological traceability to be valid, every calibration step must be documented, showing the reference standards used and the environment where the test occurred.
This documentation must also include the specific dates of the tests and the names of the certified technicians who performed them, providing a complete history of the instrument.
Uncertainty Calculation
Every measurement has a degree of doubt, and the cumulative uncertainty must be calculated and reported at each stage of the calibration chain. This combined uncertainty ensures that the final measurement result has a known margin of error. Without this calculation, the traceability chain is incomplete and cannot be used to verify the compliance of high-precision components.
Compliance Standard
Audits of manufacturing facilities look for evidence of continuous tracking of equipment calibration back to recognized standards. Utilizing metrological traceability helps companies avoid disputes with customers and regulators by providing indisputable proof of measurement accuracy. The resulting documentation protects the manufacturer from liabilities arising from out-of-specification parts.
