Die-casting is a metal-type pressure casting on a die-casting machine, which is the most productive casting skill at that time. Die casting machines are divided into two types: hot chamber die casting machine and cold chamber die casting machine. The hot chamber die casting machine has high degree of automation, less material loss, and higher production power than the cold chamber die casting machine. However, it is only restricted by the heat resistance of the machine parts. At that time, it can only be used for the casting of low melting point materials such as zinc alloy and magnesium alloy. . Aluminum alloy die castings, which are widely used today, can only be produced on cold chamber die casting machines because of their high melting point. The primary characteristic of die casting is that the molten metal fills the cavity under high pressure and high speed, and is formed and agglomerated under high pressure. The insufficiency of the die casting is that the molten metal cannot be prevented in the process of filling the cavity under high pressure and high speed. The air in the cavity is wrapped inside the casting to form the subcutaneous pores, so the aluminum alloy die-casting parts are not suitable for heat treatment, and the zinc alloy die-casting parts are not suitable for surface spraying (but can be painted). Otherwise, the internal pores of the casting will expand with heat upon heating as described above, causing the casting to deform or bubble. In addition, the machining allowance of die-casting parts should also be smaller, generally controlled at 0.5mm, which can reduce the casting component, reduce the amount of cutting processing to reduce the cost, and prevent the penetration of the fine layer of the surface and expose the subcutaneous pores. The workpiece is invalid.