Patent ID: 7661457

Claim:
A molten metal casting system comprising: a mold table which includes a mold table framework, a plurality of molds each with a mold cavity with a mold cavity inlet and a mold cavity outlet, and each mold cavity outlet including a permeable perimeter wall through which gas passes during casting; a plurality of gas supply lines, each corresponding to one of the plurality of mold cavities and each configured to provide gas to the permeable perimeter wall of the one of the plurality of mold cavities to which it corresponds; a plurality of gas mass flow controllers operatively connected to the plurality of gas supply lines, with each gas mass flow controller configured to provide an ongoing approximately constant mass flow of gas to the permeable perimeter wall of the one of the plurality of mold cavities to which it corresponds; and wherein the plurality of gas mass flow controllers maintain the flow of gas through each of the plurality of permeable perimeter walls approximately equal as the resistance to the flow of gas through each of the plurality of permeable perimeter walls varies during casting.