ISO test survey on material influence in dimensional computed tomography

ISO/TC 213/WG 10 is responsible for creating international standards (series ISO 10360) for the acceptance testing of coordinate measuring systems (CMSs). A current topic is creating a future part of ISO 10360 for CMSs using dimensional computed tomography (CT). The discussion is focussed on how to include material thickness influence in acceptance testing. ISO/TC 213/WG 10 decided to perform an experimental survey to study this topic. This ISO test survey covers several national metrology institutes and manufacturers. Reference standards under study made of aluminium are two step cylinders provided by the National Metrology Institute of Japan (NMIJ), and two hole plates provided by the Physikalisch-Technische Bundesanstalt (PTB), Germany. To check for residual errors of CT-based CMSs, additional reference standards may be measured by participants. This report details results and experiences of the participant PTB. PTB applied scaling reference measurements of a multi-sphere standard and a printed circuit board as additional reference standards, i.e. in addition to hole plate and step cylinder measurements, respectively. Measurements were performed in mid 2015 using the PTB dimensional CT system (Nikon Metrology MCT225). In this contribution, special focus is placed on the interpretation of the results and the consequences of a potential testing regime. This text does not directly describe an existing ISO standard nor a published or intended ISO standard draft. It is intended to contribute to the research of influence parameters which are relevant for a possible future part of ISO 10360 for the case of CT-based CMS (which is assumed to be part 11).