Comparison of X-ray computed tomography and coordinate-measuring system dimensional measurement for additive manufacturing parts using physical and simulation methods

This paper aims to verify the capability of X-ray Computed Tomography (XCT) in the dimensional measurement of additive manufacturing (AM) parts by comparing it against a tactile coordinate-measuring system (CMS). Three factors are investigated: XCT beam hardening, XCT voxel size scale error, and CMS mechanical filtering effect. Their performances are compared via both physical and simulation experiments. The physical experiments show that the employed XCT beam hardening elimination aids in obtaining accurate inner dimensions but deteriorates external dimension measurements. XCT voxel size scale error can be compensated by either the two-sphere calibration or the CMS normalisation method. The physical measurement results also indicate that the dimensional deviation between XCT and CMS measurements is mainly due to the mechanical filter effect of CMS, which is further sustained by simulation measurements. The proposed 3D CMS probe scanning simulation method yields a reliable uncertainty estimation of the CMS mechanical filtering effect.