On the importance of multi-material acceptance testing for CT-based CMSs – F. B. Oliveira et al.

X Ray CT/10

Abstract

As the use of multi-material objects in industry continues to rise, the need for geometrical quality control by means of computed tomography-based coordinate measurement systems (CT-based CMSs) for entire geometries is rising as well. But the lack of international standards and the limited knowledge available on the influence of multi-materials on dimensional CT measurements greatly impairs the reliability of this technology. Therefore this paper, after summarising the multi-material effects on dimensional CT measurements, will evaluate the performance of a metrology CT system for multi-material measurements. The objectives here are to gather evidence for and to better understand the multi-material influence on CT measurements. The investigation consisted of carrying out test measurements similar to standardised acceptance test measurements using a set of dedicated multi-material reference standards. The evaluation of the measurement results relied on statistical analyses and estimation of the test value uncertainty. This evaluation has validated that effects not present in mono-material measurements indeed exist in multi-material measurements, thus highlighting the importance of considering multi-material effects on dimensional CT measurements