ON THE SIMULATION OF THERMOPLASTIC INJECTION-MOLDING PROCESS

Numerical simulation of the injection moulding process of thermoplasti c polymers has been performed on the basis of the Williams and Lord mo del and its recent extensions. The aim of the simulation was to identi fy material properties which play a relevant role to process modelling , including post filling stages. Predictions improve significantly by taking into account the effect of pressure on both viscosity and cryst allisation kinetics. Several features, however, are not satisfactorily predicted. Also the relevance of convection during packing has been e videnced especially with reference to gate sealing time. As highly ori ented crystalline structures are present in the final moulded object, the enhancement of crystallisation kinetics by the effect of flow is s uggested as the phenomenon to be accounted for in order to gain a quan titative description of the whole process.