Patent ID: 8016019

Claim:
A casting method of pressure filling a molten metal from a lower side through a sprue into a cavity defined by an upper die and a lower die or into a cavity defined by the upper die, the lower die and a side die to solidify the molten metal, which comprises: using, as a material forming the sprue, a material whose heat conductivity in an operating temperature of 150° C.-550° C. is 34-41 W·(m·K) −1 , by mass content, 0.15% or more and 0.35% or less of C, 0.05% or more and less than 0.20% of Si, 0.05% or more and 1.50% or less of Mn, 0.20% or more and 2.50% or less of Cr, 0.50% or more and 3.00% or less of Mo, 0.05% or more and 0.30% or less of V, and the balance essentially Fe, and whose heat conductivity increases as the temperature decreases, the material of the sprue having a higher heat conductivity than material of the lower die and a material of the side die, and controlling the sprue to be forcibly cooled by supplying air into an air passage that is formed in the sprue at the same time that the supply of the molten metal into the cavity is stopped.