Provided is a resin for core used for injection molding, with which an inner surface of an outer molded body is less likely to be roughened, and an inner surface of a finally obtained molded body is smooth and less likely to have chipping. The resin for core includes a polyvinyl alcohol-based resin, used for an application in which a core is dissolved in water after an outer molded body is molded in an injection molding process, and includes an easy stripping agent that enhances easy stripping properties when the resin for core dissolves in a proportion of more than 0.1 wt % and less than 1.2 wt %.

A resin molding method includes a first molding step of molding a first molded part and a second molded part in a mold and a second molding step of joining the first molded part and the second molded part. In the first molding step, the second molded part is formed by injecting resin into an area where a first core movable in the first direction and a second core movable in a second direction are engaged. In the second molding step, the second molded part is joined to the first molded part by injecting the resin while the first core is in contact with the second molded part and the second core is removed from the second molded part. Areas where the first core and the second core are located in the first molding step become hollow areas connected to each other and part of ends of the first core in the first direction is not in contact with the second core.

A tool and a process for forming a vehicle component is provided. An insert has a lost core generally encapsulated by a cast metal shell. The insert has an anchor surface and a first locating member spaced apart therefrom, and is shaped to form a fluid passage in the vehicle component. A first die is configured to mate with the anchor surface and constrain the insert. A second die defines a first locator recess sized to receive the first locating member and constrain the insert. The first and second dies mate with one another to form the tool. The first and second dies constrain the insert in multiple degrees of freedom.

A resin molding method includes a first molding step of molding a first molded part and a second molded part in a mold and a second molding step of joining the first molded part and the second molded part. In the first molding step, the second molded part is formed by injecting resin into an area where a first core movable in the first direction and a second core movable in a second direction are engaged. In the second molding step, the second molded part is joined to the first molded part by injecting the resin while the first core is in contact with the second molded part and the second core is removed from the second molded part. Areas where the first core and the second core are located in the first molding step become hollow areas connected to each other and part of ends of the first core in the first direction is not in contact with the second core.