Patent ID: 8607846

Claim:
A molding manufacturing method comprising: providing a mold having a first groove part extending with a constant length or a constant width from a center part to an outer circumferential part of the mold; and a second groove part extending from a terminal end of the first groove part on an outer circumferential part side of the first groove part and merging with any portion of the first groove part, the second groove part extending between two adjacent, spaced portions of the first groove part so as to connect the two adjacent, spaced portions; manufacturing a preform by semimolten die casting or semisolid die casting using the mold such that the preform has a first molded portion corresponding to the first groove part and a second molded portion corresponding to the second groove part, the first molded portion having a terminal end that is connected to an adjacent, spaced part of the first molded portion by the second molded portion before removing the second molded portion; and removing the second molded portion of the preform corresponding to the second groove part such that the terminal end of the first molded portion becomes a free end that is free from connection with the adjacent, spaced part as viewed along a circumferential center of the first molded portion with the terminal end and the adjacent, spaced part of the first molded portion being separated by a gap, the gap being disposed where the second molded portion of the preform was disposed prior to removal.