Investigation of the influence of process parameters on dimensional accuracy and post-sintering crack formation in ceramic 3D printing for porcelain-based commercial resins

Several commercial ceramic resins are nowadays available in the market of Additive Manufacturing, making more approachable ceramic stereolithography (CS) to an extended audience of users, from academic to industrial fields. Lack of knowledge in terms of material characterization and expected behavior in the manufacturing process are the main problems that involve difficulties in obtaining precise, dense, resistant, and crack-free ceramic parts. This article presents a characterization of a porcelain-based commercial ceramic resin for digital light processing (DLP), Porcelite^® by Tethon 3D, and a study on the printing dimensional accuracy and cracks formation in sintered samples in dependence on the process parameters used have been performed. Two different Porcelite^® resins with different solid loadings are available in the market. Rheological measurements, thermogravimetry combined with differential thermal analysis, field emission scanning electron microscopy observation, and X-ray diffraction allowed the complete characterization of the most loaded ceramic suspension. A design of experiment (DoE) approach led to planning the experimental work identifying the geometry of the samples, the process parameters, and their levels of variation to evaluate the aspects that influence dimensional accuracy when printing and crack formation during thermal treatment. The final volumetric shrinkage of components produced, respectively, with Porcelite^® Bison (PB) and Porcelite^® Universal (PU) is 19.3 ± 2.2% and 41.1 ± 3.6%. Solid loadings evaluated through TG–DTA are 52 wt% for PU and 72 wt% for PB. Statistical analyses highlight that layer thickness and degree of exposure influence accuracy in x- and y-directions, and for both resins, part thickness influences accuracy only in the x-direction for PB resin. Layer thickness, part thickness, and interaction are influential in the z-direction. The printed accuracy shows certain independence from the resin solid loading.