Die casting is a metal mold pressure process performed on a die casting machine, and it is the most efficient casting process in terms of production efficiency. 

Die casting machines are divided into two categories: hot chamber die casting machines and cold chamber die casting machines. Hot chamber die casting machines have a high degree of automation, minimal material loss, and higher production efficiency than cold chamber die casting machines. However, due to limitations in the heat resistance of machine components, they are currently only suitable for producing castings made from low-melting-point materials such as zinc alloys and magnesium alloys. Aluminum alloy die-cast components, which are widely used today, have a higher melting point and can only be produced on cold-chamber die-casting machines. The main characteristic of die casting is that molten metal is injected into the mold cavity under high pressure and high speed, and then solidifies under high pressure. The drawbacks of die castings are: during the process of molten metal being injected into the mold cavity under high pressure and high speed, air in the mold cavity is inevitably trapped inside the casting, forming subsurface porosity. Therefore, aluminum alloy die castings should not be heat treated, and zinc alloy die castings should not be surface-coated with plastic (but can be painted). Otherwise, the internal porosity in the casting will expand when heated during the aforementioned treatments, causing deformation or bubbling of the casting. 

Additionally, the mechanical machining allowance for die-cast parts should be kept as small as possible, generally around 0.5 mm. This not only reduces casting weight, minimizes machining volume to lower costs, but also prevents penetration of the surface dense layer, exposing subcutaneous porosity and causing scrap of the workpiece.