Riser(s) size reduction and/or metal quality improving in gravity casting of shaped products by moving electric arc

A metal casting apparatus for reducing the size of risers and/or improving quality in discrete metal castings, the apparatus comprising:

• a) at least one plasma arc electrode for forming a continuously-moving plasma arc over the upper surface of at least one riser projecting above a metallic casting being cast in a mold;
• b) at least one stand for suspending said at least one plasma arc electrode;
• c) a second electrode attachable to a metallic surface of said mold being used for casting or to the cast metal, for completion of an electric circuit through metal cast in said mold to form a plasma arc;
• and
• d) control means connected between said apparatus and a power supply and arranged to supply power to said plasma arc electrode(s) for completion of (an) electric circuit(s) including the molten metal in the mold for forming a continuously-moving plasma arc between the upper surface of each said riser and the lower face of the corresponding said first electrode, each plasma arc flowing/stirring the molten metal in a corresponding said riser, and controls connected between said apparatus and a power supply enabling control of the electric circuit(s).