Composite core for casting

摘要

A cast product is a housing for a power steering comprising a pair of large holes for both a contact valve and a cylinder, and a small hole connected to the large holes. In order to mold such a cast product, a composite core has large core portions for the large holes and small core portions for the small hole. The large core portions include resin films used to coat the outer periphery of metal bases exposed in a cavity. The small core portions include a resin body formed of a resin connected to the resin films on the outer periphery of the metal bases.