Modelling of Cyclic 3-Dimensional Heat Transfer in Injection Moulding

Abstract A detailed 3-dimensional analysis of cyclic heat transfer in a complex injection moulding mould tool has been carried out, using a general-purpose commercial heat transfer code (FIDAP). A novel, generally applicable technique for modelling of heat loss to ambient from the tool parting surfaces is introduced, to facilitate inclusion of the mould-open period in the modelling. Simulations are continued through 30 cycles of moulding, to attainment of steady periodic conditions. During this period temperatures at the polymer-steel interface rose by between 10 °C and 40°C above the coolant temperature. At the start of cooling, values of cavity surface heat transfer coefficients referred to the coolant temperature ranged from approximately 4000 W/m2K to 400 W/m2K, with the highest values occurring directly below the cooling channels and the lowest near a heated sprue bush. At the end of the cooling period, values at each location had dropped by approximately an order of magnitude. These results illustra...