https://www.fangling-precisionmold.com/products/core-and-cavity-mold-parts/ Core And Cavity Mold Parts core and cavity are used in the injection molding process, where the concave part of the mold is the cavity and the convex part is the core. The core and cavity design in mould are used in pairs, with the cavity also referred to as the female mold and the core as the male mold.