A Simple Polymer Shrinkage Model Applied to Stereolithography

A simple polymer shrinkage model has been successfully applied to the stereolithography process. The shrinkage model, which computes specific volume changes from the degree of conversion of monomer to polymer, incorporates a lag between conversion and shrinkage. An overall process model used to simulate the stereolithography process was modified by inclusion of the shrinkage model. Use of the modified stereolithography process model allows prediction of the shrinkage that might be expected to occur when fabricating a strand of plastic. By varying the lag between conversion and shrinkage it is shown that faster shrinking resins should exhibit lower overall shrinkage than slower shrinking resins. This is a direct result of the fact that less shrinkage occurs after the strand has been scanned for the faster shrinking resins.