Patent ID: 6745817
Filing Date: 2004-06-08
Classification: B22D

Abstract:
A gravity die casting method for casting a cast product having a desired shape, comprising the steps of:using a molding die having a cavity, a sprue from which a molten metal is poured and a feeder head portion arranged between the sprue and the cavity for casting a cast product, the molding die being formed from a material having a higher heat insulating property than a material forming the cavity such that the molding die being formed has a difference of heat insulation between the feeder head portion and the cavity such that the molten metal filled in the cavity and the feeder head portion is sequentially solidified in a direction of from a terminal portion of the cavity to the feeder head portion; pouring the molten metal into the cavity of the molding die; reducing an oxide film formed on a surface of the molten metal by allowing the molten metal and a reducing compound to be contacted with each other in the cavity of the molding die; setting a cooling rate of the molten metal filled in an uncoated area of the cavity at about 500Â° C./min. or more and a cooling rate of the molten metal poured into the feeder head portion at about 500Â° C./min. or less; and solidifying the molten metal filled in the cavity, whereby at least a part of the molten metal filled in the feeder head portion is replenished in the cavity, when a void is formed by shrinkage at the time of the solidifying step.