MANUFACTURING METHOD FOR HOLLOW CAST, AND MANUFACTURING METHOD FOR PISTON FOR INTERNAL COMBUSTION ENGINE

A method of producing a hollow casting is provided, by which the joinability of a cast base material and a hollow-forming member to each ot her can be enhanced while suppressing the generation of oxides of or blow holes on a casting base material. The method of producing the hollow casting comprises enveloping a hollow-forming member in a molten base metal cast material. Specifically, the method comprises the steps of: producing a hollow-forming member with a material having a melting point higher than that of a base-metal cast material such that air-gap layers are formed within the surface layers of contact surfaces with which the molten metal comes into contact; coating the contact surfaces with a layer of the same metal as that of the base-metal cast material; and enveloping the hollow-forming member in the base-metal cast material by disposing the coated hollow-forming member within a mold and then pouring the molten base-metal cast material into the mold.