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

Metal additive manufacturing (AM) technologies can produce complex lattice structures with advantageous strength-to-weight properties, for which there is increasing interest by important industrial sectors such as aerospace, automotive and biomedical. However, the geometrical and dimensional quality of AM lattice structures needs to be assessed by adequate measurement techniques. Differently from conventional contact and optical coordinate metrology, X-ray computed tomography (CT) enables nondestructive measurements of both external and difficult-to-access features. To establish the metrological traceability of CT dimensional measurements needed to effectively improve the AM process, the task-specific measurement uncertainty must be determined. This paper investigates the possibility of using the “multiple measurements approach” for the uncertainty determination of CT dimensional measurements performed on Ti6Al4V lattice structures fabricated by laser powder bed fusion. The main advantage of this approach is that it is not limited by the unavailability of low-uncertainty calibration measurements, which is a common issue for very complex workpieces such as the lattice structures investigated in this work.