Patent ID: 7296612
Filing Date: 2007-11-20
Classification: B22C,B22D

Abstract:
1. A method of making a metal casting, comprising the steps of: providing a sand mould having a mould cavity with a shape corresponding to that of the metal casting, a launder section, primary risers connecting the launder section to the mould cavity, and a pressure riser connected to the launder section and the primary risers; placing the sand mould in a filling position whereat the primary risers extend upwardly to the mould cavity and the pressure riser extends upwardly outside the mould cavity; engaging the launder section with a liquid metal filing system; filling the mould cavity with liquid metal while the sand mould is in its filling position, thereby also filling the primary risers and the pressure riser; sealing the sand mould when the mould cavity has been filled; disengaging the sand mould from the liquid metal filling system; rotating the sand mould 180° to its inverted position; wherein, during the rotating step, the pressure riser maintains a constant pressure in the liquid metal in the mould cavity through the primary risers.