Liquid metal forming, also known as casting, is a method of injecting liquid metal into a mold to cool and solidify it to form parts. The metal products cast are called castings. The vast majority of castings are used as blanks, which can only become various machine parts after machining; A few parts can be directly used as finished products or parts when they meet the requirements of dimensional accuracy and surface roughness. Casting production can be divided into sand casting and special casting. Among all casting methods, sand casting is the most widely used method. In the world, most castings (60%~70% of the total output of castings) are produced by sand casting, followed by investment casting, centrifugal casting, metal mold casting and die casting.