Method of injecting molten metal into a mold cavity

A method of metal casting without the formation of significant gas porosity and voids for use with a metal casting apparatus including a sealable sleeve and a mold having a mold cavity formed therein, the sleeve having a plunger for pushing molten metal from the sleeve into the mold cavity, the plunger being movable from a first position at which the plunger is retracted, to a second position at which injection of the molten metal into the mold cavity begins, and to a third position at which the mold cavity is substantially full of molten metal, the method comprising:

• providing pressurized gas in the mold cavity and in the sleeve to increase the level of solubility of hydrogen in the molten metal as the molten metal travels from the sleeve prior to injection into the mold cavity, whereby to prevent the formation of significant gas porosity and voids.

A method of aluminum casting for use with an aluminum casting apparatus including a sleeve and a mold having a mold cavity formed therein, the sleeve having a plunger for pushing molten aluminum from the sleeve into the mold cavity in a manner potentially forming volumetric deficits and negative pressures in the molten aluminum as the aluminum solidifies in the cavity, the molten aluminum having a static pressure and a dynamic pressure during movement into the cavity, the method comprising:

• providing pressurized gas in the mold cavity prior to injection sufficient to generate and maintain a static pressure in the molten aluminum as the molten aluminum moves from the sleeve into the mold cavity, said static pressure being sufficient to maintain an increased level of solubility of hydrogen in the molten aluminum and to reduce volumetric deficits and negative pressures formed in the molten aluminum as the molten aluminum travels from the sleeve and solidifies in the mold cavity.

A method of metal casting for use with a metal casting apparatus including a sleeve and a mold having a mold cavity formed therein, the sleeve having a sealable feed throat and a plunger for pushing molten metal from the sleeve into the mold cavity in a potentially wave-forming manner, the plunger being movable from a first position at which the plunger is retracted, to a second position at which injection of the molten metal into the mold cavity begins, and to a third position at which the mold cavity is substantially full of molten metal, the method comprising:

• providing pressurized gas in the sleeve adjacent the molten metal prior to injection sufficient to decrease the amplitude of any waves formed in the molten metal as the plunger moves from the first position toward the second position, whereby to discourage entrapment of gases in the molten metal.

A method of improving feeding of solidifying crystal structures of molten metal as the molten metal is cast in a metal casting apparatus, the apparatus including a sleeve and a mold having a mold cavity formed therein, the sleeve having a plunger for pushing molten metal from the sleeve into the mold cavity, the plunger being movable between a first position at which the plunger is retracted, a second position at which injection of the molten metal in the mold cavity begins, and a third position at which the mold cavity is substantially full of molten metal, the method comprising:

• supplying pressurized gas in the sleeve adjacent the molten metal as the plunger is moved from the first position toward the second position;
• and
• supplying pressurized gas in the mold cavity prior to injection sufficiently to improve feeding of the molten aluminum into the solidifying crystal structures in order to reduce formation of voids and to improve metallic bonding during solidification.