Current state of standardization in the field of dimensional computed tomography

TLDR

Industrial X‑ray computed tomography is a mature non‑destructive testing technology that is increasingly used for dimensional metrology, where accurate interface positioning is critical, and standardization—such as ISO TC 213 WG 10—provides essential trust in these measurement systems. This paper examines the requirements for international standards in dimensional CT and reports on current developments from national and international standardization committees. The authors investigated hole plates as reference standards for length‑measurement error, studying how material properties influence error E and determining optimal measurement methods. Analysis of measurement data yielded an improved hole‑plate design, and the authors discuss existing approaches and anticipate future developments.

Abstract

Industrial x-ray computed tomography (CT) is a well-established non-destructive testing (NDT) technology and has been in use for decades. Moreover, CT has also started to become an important technology for dimensional metrology. But the requirements on dimensional CTs, i.e., on performing coordinate measurements with CT, are different from NDT. For dimensional measurements, the position of interfaces or surfaces is of importance, while this is often less critical in NDT. Standardization plays an important role here as it can create trust in new measurement technologies as is the case for dimensional CT. At the international standardization level, the ISO TC 213 WG 10 is working on specifications for dimensional CT. This paper highlights the demands on international standards in the field of dimensional CT and describes the current developments from the viewpoint of representatives of national and international standardization committees. Key aspects of the discussion are the material influence on the length measurement error E and how E can best be measured. A respective study was performed on hole plates as new reference standards for error testing of length measurements incorporating the material influence. We performed corresponding measurement data analysis and present a further elaborated hole plate design. The authors also comment on different approaches currently pursued and give an outlook on upcoming developments as far as they can be foreseen.