Shrinkage Deformation Research of Photosensitive Resin in Mask Projection Stereolithography

The aim of this research is to analyze the influence of shrinkage behavior on the deformation of forming parts in mask projection stereolithography. A mask projection stereolithography machine based on DLP( digital light procession) technology was designed, and the shrinkage of photosensitive resin during light-cured process was analyzed. The shrinkage behavior of resin in different exposure situations, free-surface and constrain-surface, and also in secondary curing process was studied. The result shows that in free-surface, the shrinkage of B5B type resin is proportional to the exposure time, eventually it stabilizes at around 4%. When it is in constrain-surface, the overflowed light curing effect leads to shrinkage which decreases with exposure time increased, and the shrinkage generated in the secondary curing process accounts for 40% ~50% of total.