Studious. Inquired about the recruitment information released by official website of Ruihang Foundry in Jize County, showing that the core-making machine in the factory is made of sand, which is responsible for the core in the post, and because it is sand, it doesn't take much effort, so it is very easy to learn. Core-making is core punching, the core is made of sand, and a workpiece is cast with a mold, which is divided into two parts.