Casting is the process of pouring molten metal liquid into the mold, cooling and solidifying to obtain the required shape and performance of parts. Casting is a commonly used manufacturing method with low manufacturing costs and high process flexibility, which can obtain complex shapes and large castings. It occupies a large proportion in mechanical manufacturing, such as machine tools accounting for 60-80%, automobiles accounting for 25%, and tractors accounting for 50-60%.

The casting process can be divided into sand mold casting process and special casting process.

Sand casting

Sand casting is a traditional casting process that uses sand as the main molding material to make molds.

Sand casting mainly adopts gravity casting process:

Gravity casting refers to the process of injecting molten metal into a mold under the influence of the Earth's gravity, also known as casting. Generalized gravity casting includes sand casting, metal casting, investment casting, mud casting, etc; The narrow meaning of gravity casting specifically refers to metal mold casting.

Sand molds generally use gravity casting, 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, including small and large parts, simple and complex parts, single parts, and large batches. The molds used for sand casting were previously mostly made of wood, commonly known as wooden molds. The disadvantages of wooden molds are easy deformation and damage; In addition to single piece sand castings, aluminum alloy molds or resin molds with higher dimensional accuracy and longer service life can be used. Although the price has increased, it is still much cheaper than molds used for metal mold casting, and the price advantage is particularly prominent in small batch and large piece production. In addition, sand molds have higher fire resistance than metal molds, so materials with higher melting points such as copper alloys and black metals also use this process more frequently. However, sand casting also has some shortcomings: because each sand mold can only be poured once, the mold is damaged after obtaining the casting and must be reshaped, so the production efficiency of sand casting is relatively low; Due to the overall soft and porous nature of sand, the dimensional accuracy of sand casting castings is low and the surface is also rough.