An apparatus and process are provided for casting liquid metals into molds in a casting furnace comprising a controlled environment melt chamber and a mold lock chamber. A mold is supplied to the controlled environment melt chamber for a pour, and removed from the same chamber via a mold lock chamber. A mold transport system moves the mold through the mold lock chamber. The mold transport system comprises a rotary screw drive, a cylinder screw drive, or hydraulic drive located external to the furnace. Alternatively the mold transport system comprises a rack and worm screw drive.