Color appearance in rotational material jetting

Abstract

Material jetting (MJT) is a recognized additive manufacturing (AM) method to combine various materials and create a wide range of designed appearances. However, the measured color of MJT objects is frequently different from the color provided in the printer software. As a result, estimating the color quality and the measured color attributes of an object before printing is vital for accurate color reproduction. This study investigates the color variation based on the texture in an object 3D-printed using the MJT method on a rotary tray. The novel radial shape of the rotary tray build platform and variation in the layers structure were targeted as the main factors that can increase the uncertainty in accurate color reproduction. The influence of the PolyJet printer setup has been examined by thickness variation of the colored layers, location on the tray (swath selection), ink color, and finish type between layers. Color quality was assessed by comparing the produced object color by calculating spectral and colorimetric differences. Spearman rank correlation coefficient and principal component analysis (PCA) methods were used to analyze the direct or indirect influence of independent categorical factors on the measured color variables. Based on the studied parameters, switching swathes did not fail printer objects for industrial color matching. In contrast, a thickness variation as small as 0.5 mm could cause CIEDE2000 above 5 for most models, resulting in unnatural color reproduction. Color differences in most objects might be discernible to inexperienced observers, depending on the 3D printing parameters.