Measurement of additively manufactured surfaces with re-entrant features by x-ray computed tomography

Components produced by additive manufacturing (AM) technologies are typically characterized by complex surface topographies, including the presence of micro-scale and freeform-shaped re-entrant features. Such surfaces can be external or internal. The most commonly used techniques for topography measurements (i.e. contact probing and optical techniques) cannot access and measure neither internal surfaces nor re-entrant surface features. X-ray computed tomography (CT) has recently started to be used as a viable alternative technique capable of obtaining topographical measurements of AM surfaces at micro-scale. However, the most commonly used texture parameters –defined in ISO 4287 for profile measurements and in ISO 25178-2 for areal measurements– are not designed for taking into account complex re-entrant features. This work proposes a new generalized definition for a selection of profile texture parameters, suited to characterize complex AM surface profiles including re-entrant features measured by CT. Such parameters were used to evaluate the accuracy of CT topography measurements of AM surface profiles in comparison to reference measurement