Pressure Die Casting

Pressure Die Casting is a kind of precision casting method that uses high pressure to melt metal into complex metal mold.

Die casting machines can be divided into two different types: hot chamber die casting machine and cold chamber die casting machine. The difference lies in how much force they can bear. The typical pressure range is between 400 and 4000 tons.

Hot chamber die casting

Hot chamber die casting, sometimes called gooseneck die casting, its metal pool is molten liquid and semi liquid metal, which fills the mold under pressure. At the beginning of the cycle, the piston of the machine is in a contracted state, and the molten metal can fill the gooseneck. The pneumatic or hydraulic piston squeezes the metal and fills it into the mold. The advantages of this system include high cycle speed (about 15 cycles per minute), easy automation, and convenient melting of metal. Disadvantages include the inability to die cast metals with high melting points, as well as aluminum, which will bring iron out of the melting pool. Therefore, hot chamber die casting machines are generally used for alloys of zinc, tin and lead. Moreover, hot chamber die casting is difficult to be used for die casting large castings. Usually, this process is die casting small castings.

Cold chamber die casting

When die casting cannot be used for metals in hot chamber die casting process, cold chamber die casting can be used, including aluminum, magnesium, copper and zinc alloy with high aluminum content. In this process, the metal needs to be melted first in an independent crucible [2]. A certain amount of molten metal is then transferred to an unheated injection chamber or injection nozzle. These metals are injected into the mold by hydraulic or mechanical pressure. Due to the need to transfer molten metal into the cold chamber, the biggest disadvantage of this process is the long cycle time. Cold chamber die casting machines can also be divided into vertical and horizontal. Vertical die casting machines are usually small machines, while horizontal die casting machines have various models.

Die Casting Mould

The die casting die consists of two parts, covering part and moving part, and the part they combine is called parting line. In hot chamber die casting, the covering part has a gate, while in cold chamber die casting, it is an injection gate. Molten metal can enter the mold from here. The shape of this part matches the injection nozzle in hot chamber die casting or the injection chamber in cold chamber die casting.

The movable part usually includes push rod and runner. The so-called runner is the channel between gate and mold cavity, through which molten metal enters the mold cavity. The covering part is usually connected to the fixed pressing plate or the front pressing plate, while the movable part is connected to the movable pressing plate. The cavity is divided into two cavity inserts, which are independent components and can be relatively easily removed or installed from the mold by bolts.