How uncertain can (geometric) measurements be for a conformity and non-conformity assessment?

Abstract The document JCGM 106:2012 outlines two probability-based approaches for evaluate the conformity or non-conformity of a measured value with a specification in Chapters 7 and 8. The ISO 14253-1:2017 is the applicable standard for conformity and non-conformity assessment using a probability-based approach with guard bands for measurement values from geometric measurements. The article presents a possible extension of the ISO 14253-1:2017 to enable the practical application and the use of various distribution functions and the results of a measurement uncertainty determination with Monte Carlo simulation. The article focuses in particular on the questions of which types of distribution functions should be assumed for the measurands depending on the number of measurement points and the value of the measurand, as well as what the effects are for two probability-based approaches from JCGM 106:2012 Chapters 7 and 8 when there is a large measurement uncertainty compared to the tolerance, and what needs to be taken into account. The influence of a measurement uncertainty which is too large in comparison to the tolerance is illustrated in the three relevant cases for both approaches, thus highlighting the need for an appropriately small measurement uncertainty for conformity and non-conformity assessment.