Failure of rapid prototype molds during injection molding

Stereolithography rapid tooling materials (typically epoxy-based photopolym ers) show great promise for injection molding of limited numbers of parts, greatly reducing the time to product. Yet, they present challenges to desig ners because of their strength, thermal characteristics, and shorter lifeti mes as compared to other mold materials. This paper presents models of the forces generated during the injection molding cycle so as to evaluate the s uitability of rapid tools. The models comprise thermal and mechanical loadi ng during injection, cooling shrinkage, and ejection. The effects of proces s conditions on material properties are studied. Experimental results are p resented.