A numerical simulation approach for plastics injection molding is developed where the goal is to predict the final shape of a product which is also affected by the ejection stage. The modeling of the filling, packing and cooling stages is conducted in the scope of computational fluid dynamics. The residual stresses in the part are predicted in the scope of solid mechanics using the finite element method. The model includes the rheology of solid high density polyethylene. The ejection contact problem and cooling to room temperature are simulated.