Casting can be divided into gravity casting and pressure casting. Gravity casting is the process of injecting molten metal into the mold under the action of gravity.

Die casting is a kind of die casting machine, which is the most efficient casting technology. Die casting machine is divided into hot chamber die casting machine and cold chamber die casting machine two categories. Hot chamber die-casting machine a high degree of automation, less material consumption, the production efficiency is higher than the cold chamber die casting machine, but restricted by mechanical heat capacity, at present can only be used in casting production of zinc alloy, magnesium alloy and other low melting point materials. Today's widely used aluminum alloy die castings, due to the high melting point, can only be produced in cold chamber die casting machine. The main characteristics of die casting is the molten metal in the cavity filling under high pressure and high speed, and under high pressure forming, solidification, deficiency of die casting is: because the liquid metal in the process of high pressure, high speed filling cavity, inevitably the cavity in the air wrapped in the castings, the formation of blowhole so Aluminum Alloy die casting for heat treatment, zinc alloy die casting surface spray (but not painting). Otherwise, when the inner hole of the casting is heated, the heat distortion of the casting can be caused by the thermal expansion. In addition, die casting mechanical machining allowance should be made smaller, generally about 0.5mm, can reduce casting weight, reduce cutting amount to reduce the cost, but also can avoid the penetration of surface dense layer, exposing the blowhole, cause the scrap.