Production method of castings and gas-permeable casting mold

A method for producing a casting using a gas-permeable casting mold comprising a cavity composed of a production cavity and a flow path, said flow path comprising a sprue through which a gravity-poured melt flows downward, and a runner connecting said production cavity to said sprue, comprising

• gravity-pouring a metal melt in a volume smaller than that of the entire cavity and larger than that of said production cavity into said gas-permeable casting mold;
• supplying a gas through said sprue to push said metal melt in said flow path, thereby pushing said metal melt upward in said production cavity, so that said production cavity is filled with said metal melt;
• in a hypothetical equilibrium state in which a hypothetical liquid free from solidification, evaporation, expansion, shrinkage, intrusion into a casting mold, and the absorption and desorption of a gas fills said production cavity by the supplied gas, calculating the volume of said hypothetical liquid, such that the surface height hs of said hypothetical liquid remaining in said flow path after filling said production cavity, the height h1 of the lowest ceiling portion of said runner, and the height h2 of a point at which a ceiling of said runner is connected to said sprue, meet the relation of h2>hs>h1;
• and the height ht of the highest bottom portion of said runner meet hs<ht;
• and
• setting the volume of said metal melt to be poured to be equal to the volume of said hypothetical liquid.