A core is a mold component made from sand that allows us to form an internal geometric shape within a casting or in back draft areas. Cores are created by packing sand in a core box made of wood, plastic or metal. Depending on the complexity level of the desired casting, one or more cores might be required when manufacturing the mold.
The sand core process uses chemically bonded sand, which is obtained by mixing high silica sand, two different resin types and a catalyst which reacts with the resin to harden the mixture in the desired shape. This process is adapted to create both small and large-sized cores. The sand is poured into a core box. In less than a minute, it hardens and it is ready to be unmolded. The core is inserted into the mold before pouring.
This process consists of creating a shell core by using sand, resin and heated tooling (a metal core box). The sand mixture is injected between two metal plates and is heated until a thin, rigid shell is formed. This type of core makes it possible to have a really good surface finishing with very precise details. This process is also faster than chemically bonded sand since many cores can be made in the same time.