Molding method of complicated inner runner mold core

The invention discloses a molding method of a complicated inner runner mold core. The complicated inner runner mold core comprises a metal shell (1) and shape retaining sand (2). According to the molding method, an inner runner cavity contour with the high precision and smooth surface is obtained through a material additive manufacturing method. Through electrochemical material additives, the metal shell (1) of the complicated inner runner mold core is obtained, and the high-collapsibility shape retaining sand (2) is filled into the runner metal shell (1) to improve the strength of the complicated inner runner mold core. During final casting, the metal shell (1) of the complicated inner runner mold core and a casting metal solution are fused together through atomic diffusion to obtain an inner runner casting with the high precision and smooth surface. After cooling, the high-collapsibility shape retaining sand (2) can be poured out easily. Through the molding method, the problems thatthe complicated mold core