Modeling effects of oxygen inhibition in mask‐based stereolithography

Abstract

PurposeThe purpose of this paper is to present a model that can be used to simulate the photopolymerization process in micro‐stereolithography (SL) in order to predict the shape of the cured parts. SL is an additive manufacturing process in which liquid photopolymer resin is cross‐linked and converted to solid with a UV laser light source. Traditional models of SL processes do not consider the complex chemical reactions and species transport occurring during photopolymerization and, hence, are incapable of accurately predicting resin curing behavior. The model presented in this paper attempts to bridge this knowledge gap.Design/methodology/approachThe chemical reactions involved in the photopolymerization of acrylate‐based monomers were modeled as ordinary differential equations (ODE). This model incorporated the effect of oxygen inhibition and diffusion on the polymerization reaction. The model was simulated in COMSOL and verified with experiments conducted on a mask‐based micro‐SL system. Parametric studies were conducted to investigate the possibilities to improve the accuracy of the model for predicting the edge curvature.FindingsThe proposed model predicts well the effect of oxygen inhibition and diffusion on photopolymerization, and the model accurately predicts the cured part height when compared to experiments conducted on a mask‐based SL system. The simulated results also show the characteristic edge curvature as seen in experiments.Research limitations/implicationsA triacrylate monomer was used in the experiments conducted, so results may be limited to acrylate monomers. Shrinkage was not considered when comparing cured part shapes to those predicted using COMSOL.Originality/valueThis paper presents a unique and a pioneering approach towards modeling of the photopolymerization reaction in micro‐SL process. This research furthers the development of patent pending film micro‐SL process which can be used for fabrication of custom micro‐optical components.