Casting can be divided into gravity casting and pressure casting according to the pouring process of metal liquid. Gravity casting refers to the process of metal liquid injection into the mold under the action of earth gravity, also known as casting. Generalized gravity casting includes sand casting, metal casting, investment casting, lost casting, mud casting, etc. Narrow gravity casting refers specifically to metal mold casting. Pressure casting refers to the process in which liquid metal is injected into the mold under the action of other external forces (excluding gravity). The generalized pressure casting includes pressure casting and vacuum casting, low pressure casting, centrifugal casting, etc. Narrow sense of pressure casting refers to the metal mold pressure casting machine, referred to as die casting. Precision Casting plant has been engaged in gravity casting of sand and metal molds for a long time. These casting processes are currently the most commonly used in non-ferrous metal casting, but also the lowest relative price.

Die casting is the metal type pressure casting on die casting machine, which is the casting process with the highest production efficiency at present. Die casting machine is divided into hot chamber die casting machine and cold chamber die casting machine two types. Hot chamber die casting machine has high automation degree, less material loss and higher production efficiency than cold chamber die casting machine. However, limited by the heat resistance of the parts, it can only be used for the casting production of zinc alloy, magnesium alloy and other low melting point materials at present. Aluminum alloy die casting, which is widely used today, can only be produced on cold chamber die casting machines because of its high melting point.

The main characteristic of die casting is that the metal liquid fills the cavity under high pressure and high speed, and forms and solidifies under high pressure. The shortcomings of die casting are as follows: Because in the process of filling the cavity with metal liquid at high pressure and high speed, the air in the cavity is inevitably wrapped in the inside of the casting, forming subskin pores, so the aluminum alloy die casting is not suitable for heat treatment, and the zinc alloy die casting is not suitable for surface spraying (but can be painted). Otherwise, the internal pores in the casting will be heated by heat expansion resulting in casting deformation or bubbling. In addition, the mechanical cutting allowance of die casting should also be smaller, generally about 0.5mm, which can reduce the weight of the casting, reduce the cutting amount to reduce the cost, and avoid penetrating the dense layer on the surface, exposing the subcutaneous pores, resulting in the scrap of the workpiece.