Casting can be divided into gravity casting pressure casting according to the pouring process of liquid metal.
Gravity casting refers to the process of injecting molten metal into the mold under the action of the earth's gravity, also known as casting. Gravity casting in a broad sense includes sand casting, metal casting, investment casting, EPC, mud casting, etc.; gravity casting in a narrow sense refers to metal casting.
Pressure casting is a process in which liquid metal is injected into the mold under the action of other external forces (excluding gravity). The broad sense of pressure casting includes pressure casting vacuum casting, low pressure casting, centrifugal casting, etc.; the narrow sense of pressure casting refers to the metal mold pressure casting of the pressure casting machine, which is called die casting for short. Precision casting factory has been engaged in gravity casting of sand mold metal mold for a long time. These kinds of casting processes are commonly used in the current non-ferrous metal casting, but also relatively low price.
Die casting is a kind of metal mould pressure casting on die casting machine, which is a casting process with high production efficiency at present. Die casting machine is divided into hot chamber die casting machine cold chamber die casting machine. The hot chamber die casting machine has high degree of automation, less material loss higher production efficiency than the cold chamber die casting machine. However, restricted by the heat-resistant ability of the parts, it can only be used for the production of low melting point materials such as zinc alloy magnesium alloy at present. The widely used aluminum alloy die casting can only be produced on the cold chamber die casting machine because of its high melting point.
The main feature of die casting is that the metal liquid fills the cavity under high pressure high speed, forms solidifies under high pressure. The disadvantages of die casting are: because the air in the cavity is inevitably trapped in the casting to form subcutaneous pores in the process of filling the cavity under high pressure high speed, so the aluminum alloy die casting is suitable for heat treatment, the zinc alloy die casting is suitable for surface treatment Spray (but spray). Otherwise, when the air hole in the casting is heated by the above treatment, it will encounter thermal expansion cause the casting to deform bubble. In addition, the machining allowance of die casting should also be smaller, generally around 0.5mm, which can only reduce the weight of the casting, reduce the amount of machining to reduce the cost, but also avoid penetrating the surface dense layer, exposing the subcutaneous pores, resulting in workpiece scrap.