Simulating filling and solidification of AZ91 magnesium alloy in gravity die casting

Die casting of magnesium occupies an increasing place in the production of parts and aggregates in the motor car industry. The characteristic qualitie s of magnesium and wall thicknesses used in these products are conditional on the careful design of the gating system of the die and of the progress o f solidification. The temperature fields of cast plates were simulated and different heat transfer coefficients between casting and die were assumed u ntil a coefficient was established that produced only a small deviation bet ween the values measured in the casting, the die and those calculated. A fu rther case simulated a gravity die cast box of varying wall thicknesses tha t was cast while being rotated. By this means casting conditions were evolv ed that assured the production of a defect-free casting. This paper demonstrates the capability of the analytical programme to produ ce a reliable simulation and to optimise the relevant conditions in gravity die casting.