Effect of build orientation and part thickness on dimensional distortion in material jetting processes

Purpose The purpose of this paper is to elucidate the effect of part thickness and build orientation upon the type and magnitude of distortion in material jetting processes. Design/methodology/approach Specimens with high (10:1) aspect ratio were printed in two orientations (XY and YX) and three thickness values (1, 3 and 6 mm) and scanned with a white-light profilometer to quantify distortion. Findings The results of this paper indicate that 1-mm thick specimens always distorted following a wavy edge type, while thicker specimens (3- and 6-mm) always distorted following a reverse coil set. The factor thickness, when measured with the indices height of the highest peak (H) and profile radius (R), was shown to be statistically significant, with 3-mm specimens experiencing distortions of 57 and 51 per cent, respectively, more severe than those in 6-mm specimens. The thickness effect is attributed to the percentage of build layers that receive maximum energy exposure (61-72 per cent in 1-mm, 87-91 per cent in 3-mm and 93-95 per cent in 6-mm specimens). With respect to the thinner 1-mm specimens, the factor orientation was found to be statistically significant with distortion 114 per cent less severe in the YX orientation when measured by the H index. Originality/value This paper provides the first known description of build orientation and part thickness effects on dimensional distortion as a pervasive consequence of the curing process in photopolymerization and explores one of the most common defects encountered in additive manufacturing. In addition to the characterization of the type and magnitude of distortion, the contributions of this paper also include establishing the foundation for design guidelines aiming at minimizing distortion in material jetting.