The influence of the thermal history experienced during injection molding on the mechanical properties of polycarbonate is investigated. Distributions of the yield stress as they result from inhomogeneous cooling during processing, predicted by a previously developed modeling approach, are validated and are in good agreement with experiment. Predictions of the mechanical performance for different mold temperatures during processing are also validated over a range of applied strain and deformation rates and applied stresses and forces, for simple tensile bars and an actual product. Good agreement is found. It is shown that mold temperature has a tremendous influence on the life time of polymer products, which can differ by more than two orders of magnitude.