X-ray Computed Tomography for Wall Thickness Evaluation and Through-Hole Detection in Additively Manufactured Hollow Lattice Structures

Abstract

This study investigates the trade-off between minimizing wall thickness and through-hole formation in AlSi10Mg thin hollow lattice structures produced via laser powder bed fusion. X-ray computed tomography (XCT) is employed as a metrological tool to evaluate the effects of laser linear energy density (LED) across conditions ranging from under-melting to over-melting using a single laser track strategy. An XCT-based algorithm is developed for automated through-hole detection, providing quantitative data on through-hole count and size. The algorithm's capability is evaluated through leakage tests. The substitution method, adapted from ISO 15530–3 for tactile coordinate measuring machines (CMM), is employed to assess XCT measurement uncertainty for hollow lattice dimensions. As a new addition to the conventional substitution method, the effects of high-density data generated by XCT are assessed against the calibrated diameters obtained from low-density CMM data and used for the calculation of wall thickness. Experimental results show that under-melting conditions can produce wall thicknesses of 0.135 mm to 0.212 mm, with an exponential increase in through-hole formation as LED decreases. A linear relationship between LED and wall thickness is observed, enabling identification of optimal parameters for producing defect-free thin-walled structures.