Molten metal velocities and gas pressures in die cavity of commercial aluminum pressure die-casting

Abstract

Molten metal flow behavior during fast shot injection with 500 to 1650 ton commercial die casting machines was studied in the filling portion of the die cavity in the shape of disc, box and plate. The velocity of the molten metal is as high as 15 to 20m/s at the gate of a die cavity, but it decreases abruptly within a passage of 20 to 25cm and reaches 2 to 3m/s at the final filling portion, irrespectively of the tested cavity shapes. The gas pressure in the cavity shows a maximum value when the flow reaches the probe. The gage pressure increases from 0.1 to 0.2kgf/cm² at the gate to 1 to 2kgf/cm² at the final filling portion. The velocity of metal decreases with increase in the gas pressure at the final filling portion. Its abrupt decrease in practical aluminum casting is attributable to the pressure rise in the cavity. Provision of an appropriate gas vent in the final filling portion increases the velocity of the molten metal.