Vacuum-assisted, countergravity casting apparatus and method

Apparatus and method are provided for vacuum-assisted, countergravity casting a melt into a gas permeable mold having an upstanding fill sprue that supplies melt to a mold cavity via a lateral ingate. Subambient pressure is applied to the mold fill sprue and to the mold cavity when a lower open end of the sprue and an underlying source of the melt are communicated to urge the melt upwardly to fill the sprue and the mold cavity. Thereafter, the pressure applied to the mold sprue is selectively raised relative to the subambient pressure applied to the mold cavity to cause the melt in the sprue to drain therefrom without siphoning the melt from the melt-filled mold cavity. Pressurized gas can be introduced into the mold sprue as the mold is communicated to the melt source to blow floating slag and other debris away from the region of communication between the sprue lower open end and the source to reduce entry of slag into the mold cavity.