Conformity assessment of measuring equipment within the process of calibration on the example of geometrical product specification measuring instruments

Conformity assessment of measuring equipment, which can also be called verification, can be provided within the process of calibration in accredited calibration laboratories in accordance with the requirements of ISO/IEC 17025:2017 “General requirements for the competence of testing and calibration laboratories” on customer's request. However, the task execution in practice is often associated with significant difficulties due to the lack of laboratory personal's knowledge in the fi eld of probability theory and theoretical metrology, as well as the absence of clear and unambiguous rules for the task execution methods. The paper describes and analyzes the process of performing conformity assessment, which can be applied to any type of measuring equipment, and considers its particular elements, such as equipment requirements, decision rule, risk of a false decision and measurement uncertainty. The rules for performing conformity assessment for geometrical product specifications standardized in international standards ISO 14253 series are analyzed here. By using the example of calibration of a geometrical product specifications measuring instrument, such as a caliper, the article presents three scenarios of conformity assessment, based on different decision rules and different evaluation methods of measurement uncertainty. The statements of conformity acquired from the different scenarios of the caliper conformity assessment were inconsistent; they were analyzed and the above-mentioned scenarios were assessed for their validity in practice. The research results can be used for the development of conformity assessment procedures in accredited calibration laboratories performing the measurements of geometrical product specifications as well as the other types of measurement; they will also contribute to improving the qualification level of specialists involved in the conformity assessment and verification activities of various objects.

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