A computational model for stereolithography apparatus (SLA) 3D printing

Stereolithography apparatus (SLA) 3D printing involves scanning a laser across a photosensitive resin to cure it and build a part layer-by-layer. Conventionally, SLA printers are calibrated by conducting numerous experiments and analyzing the built parts to determine the optimal parameters that maximize the part quality while keeping the build-time low. This work aims to develop a computational model of the printer that characterizes the effect of these material and process parameters on the printing speed and part quality. This model could significantly reduce the time and capital required to calibrate these printers. The printing process is modeled by independently studying the resin curing and recoating processes and then combining the two phenomena. These studies were used to draw various insights into the printing process. A parametric analysis of the cure depth concluded that it significantly decays with increased laser scanning speed, whereas an optimum intermediate value of photoinitiator concentration maximizes it. A computational fluid dynamics (CFD) model of a gravity-based resin recoating process was developed and implemented in OpenFOAM®. Studies conducted using this model indicated that lower resin viscosity and higher surface tension lead to lower settling times. Inferences gained by studying the coupled model were used to develop a method to compensate for disturbances in the surface profile of the resin. SLA printer manufacturers could use the insights gained from these studies to optimize the printers to improve their speeds and print quality.