Gravity casting refers to the process of injecting molten metal into a mold under the action of the earth's gravity, also known as casting. The generalized gravity casting includes sand casting, metal casting, investment casting, lost foam casting, mud casting, etc.; the narrow gravity casting specifically refers to metal casting. The molten metal is generally poured into the gate manually, and the product is obtained by filling the cavity, exhausting, cooling, and opening the mold by its own weight. The process flow is: smelting, casting filling, exhaust, cooling, mold opening, heat treatment, and metal processing. Pressure casting is divided into two types: high pressure casting and low pressure casting. High-pressure casting is a casting method in which molten alloy liquid is poured into a press chamber, the cavity of a steel mold is filled at high speed, and the alloy liquid is solidified under pressure to form a casting.