WCA September 2022

Technical Article

Conclusion Traceability is the key to all measurements. The concept of tracing all physical parameters to a set of common references (one for length, one for weight and so on) is the foundation of all measurement technology. When we understand and accept this premise, it is natural to start exploring the next important parameters in this field, which are accuracy and precision. References • International Bureau of Weights and Measures (BIPM): https://www.bipm.org

• Physicalisch-Technische Bundesanstalt (PTB): https://www.ptb.de

• Wikipedia article about the metre: https://en.wikipedia.org/wiki/metre

• About the accuracy classification of tape measures: Directive 2004/22/ EC of the European Parliament and of the Council of 31 March 2004 on Measuring Instruments, Annex MI-008 Material Measures (p72): https://eur-lex.europa.eu/legal-content/en/txt/pdf/?uri=celex:32004L 0022&from=en

Conoptica traceable calibration object

measurements and definitions. They will usually keep a reference, or equipment to verify a reference to the standard definition. When the Swedish manufacturer wants to make a tape measure, it goes to its institute of standards and gets a reference measurement. It brings this back to the factory and calibrates the manufacturing process so that the markings on its tape measures come within the required accuracy. How do we handle traceability in Conoptica? The Calibration Certificate Conoptica’s Calibration Certificate is our documentation to our customers that their Conoptica system is providing traceable measurements. When we assemble a system, we calibrate it. The same happens after a preventive maintenance or a repair. This means that we measure a set of reference objects, then ‘tell’ the system what the sizes of these objects are. Our reference objects are traceable in the following way. We use several different objects for the calibration process. Since we measure diameters and ovality of round holes (among other things), one of our reference objects is a coated glass plate. The coating has circular holes with specific sizes. One such glass plate is our Company Reference. This plate has been measured by the National Metrology Institute of Germany, the PTB (Physicalisch-Technische Bundesanstalt). Their method is described in a long and highly technical document and contains a reference back to the metre definition. All our calibration objects are referenced to this Company Reference Plate. After the completed calibration, we create a set of customer references (for the wire and cable systems we use regular drawing dies). These are the objects you can use to validate the calibration and so ensure that the traceability of their measurements is intact. For you, that means that when you use a Conoptica system to measure a certain object, you can expect the value you obtain to be as close to the true value as our specified accuracy claims.

Conoptica AS Hallsetvegen 3 NO-7540 Trondheim Norway

conoptica@conoptica.com https://conoptica.com

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September 2022