Sand casting is a traditional casting process that uses sand as the main modeling material to make molds. Gravity casting is generally used for sand molds, and low pressure casting, centrifugal casting and other processes can also be used when there are special requirements. Sand casting has a wide range of adaptability, small pieces, large pieces, simple pieces, complex pieces, single pieces and large quantities can be used. The molds used for sand casting were mostly made of wood in the past, and are commonly called wooden molds. Although the price has increased, it is still much cheaper than the mold for metal casting. In the production of small batches and large parts, the price advantage is particularly prominent. In addition, sand molds have higher refractoriness than metal molds, so materials with higher melting points, such as copper alloys and ferrous metals, also use this process. However, sand casting also has some shortcomings: because each sand mold can only be poured once, the mold is damaged after the casting is obtained and must be reshaped, so the production efficiency of sand casting is low; and because the overall nature of sand is soft However, it is porous, so the dimensional accuracy of sand castings is lower and the surface is rougher.