Thermoviscoelastic behavior of film-insert-molded parts prepared under various processing conditions

Film-insert-molded (FIM) tensile specimens were prepared under various molding conditions to investigate the effects of wall temperature and packing pressure on the residual stress distribution and thermoviscoelastic deformation. The warpage of the specimen increased with increasing mold-wall temperature difference and decreased with increasing packing pressure. The FIM specimens produced with unannealed films showed the warpage reversal phenomenon (WRP) during annealing and the degree of WRP was affected significantly by the molding conditions and thermal shrinkage of the film. The warpage of the specimen was predicted by three-dimensional flow and stress analyses and the prediction was in good agreement with the experimental results.