Accuracy of X-ray computed tomography dimensional measurements of additively manufactured metal lattice structures

Metal additive manufacturing (AM) technologies are capable of producing highly complex and customizable lattice structures with advantageous strength-to-weight properties, which are of growing interest in several industrial sectors, including aerospace and biomedical. However, the geometrical and dimensional quality of AM lattice structures – which often needs improvements to meet specific industrial requirements – needs to be assessed by adequate measurement techniques. Differently from conventional contact and optical coordinate metrology, X-ray computed tomography (CT) enables non-destructive measurements of both external and difficult-to-access struts, as well as of internal defects and features. The accuracy of CT measurements – fundamental to effectively improve the AM process – is investigated in this work using a metrological CT system to scan Ti6Al4V lattice structures fabricated by laser powder bed fusion. In particular, methods for the determination of measurement errors and uncertainty are studied, with the aid of a new reference object specifically designed and produced for the purpose.