Influence of surface roughness on X-ray computed tomography dimensional measurements of additive manufactured parts

In many industrial applications, components characterized by high surface roughness are measured by X-ray computed tomography (CT). This is the case, for example, of additive manufactured parts. Surface roughness has a strong influence on CT dimensional measurements, causing relevant measurement deviations with respect to tactile reference measurements by coordinate measuring machines (CMMs), especially for parts characterized by high surface roughness. It comes that roughness effects on CT dimensional measurements must be quantified. In this work, the influence of surface roughness on CT dimensional measurements, and the relation between tactile CMM and CT measurements are studied. Effects of larger as well as smaller surface roughness are taken into account, by means of three different additive manufactured samples characterized by different roughness. Experimental results prove the presence of a systematic error between tactile and CT measurements; the relation between this error and the Rz roughness parameter of the surface is analyzed