Linear Shrinkage of Stereolithography Resins

The linear shrinkage of an acrylate and an epoxy based stereolithography resin was measured during cure. A helium-cadmium (He-Cd) laser cured strands of resin as is done in the stereolithography process using two exposures. The exposure time was held constant while the delay time between exposures was varied. It was found for both resins that the final cure depth and linear shrinkage were a function of delay time