Modeling of air back pressure in die-casting dies

Abstract In high-pressure die-casting, molten metal is injected into a die cavity at a high velocity. The metal entering into the cavity expels the air from the cavity through the vents. Air back pressure will be created when the volume of metal flow exceeds the volume of air escaping out of the die cavity. A new mathematical model is proposed for the calculation of the creation of the back pressure in a die cavity. Air discharge through vents is modeled by the Poiseuille flow. The differential equation of the time rate of change of the back pressure is derived. The creation of the back pressure is correlated with the configuration sizes of the vent, and computations are carried out for different configurations of the vent geometry.