Die casting is a process employing the pressure to inject molten metal into a mold or die, then to obtain the casting products that have exact shapes or geometries as the internal shape of the mould. In this article, we’ll talk about the equipment for this process, what is die casting machine and common types of die casting machines, as well as their mechanism and selection.
Die casting machine is used for the metal casting process, through which the molten metal is injected into the mold cavity, the shape of the die casting parts will be formed when the metal is cool and solidified, this is a manufacturing method to get metal castings like aluminum or zinc die castings.
Die casting machines can be divided into different categories according to different classification methods, such as application and size. Generally, die casting machines can be classified into two types: hot chamber and cold chamber.
Hot Chamber Die Casting Machine
Hot chamber machines have a pressure chamber connected to the mold cavity, the molten metal can flow to the pressurized compartment continuously. When the chamber’s cylinder reverts to an unpressurized position, molten metal is fed into the casting die. The crucible for melting metal is attached to the machine, and the piston mechanism for hydraulic injection of metal into the mold is installed in the crucible. Some hot chamber die casting machines use compressed air to directly press metal into the mold, the piston mechanism is not needed. The injection mechanism is submerged in the molten metal, so it’s necessary to avoid chemical attack or erode to the submerged injection system. Hot chamber die casting machine is mainly used for casting zinc, tin and other alloys with a low melting point.
Advantages of hot chamber die casting machine
– High productivity
– Improved surface finish
– Capable of production of intricate castings
– Close dimensional tolerance
– Suitable for making zinc die casting parts
Cold Chamber Die Casting Machine
In a cold chamber machine, molten metal from a separate holding furnace is ladled into the cold chamber sleeve after the mold is closed. Then the metal is forced into the die, open the mold after solidification, the casting part will be injected. The metal is melted outside the machine, and then is added into the compression chamber. According to the moving direction of the compression piston, it can be divided into vertical cold chamber die casting machine and horizontal cold chamber die casting machine. The molten metal is taken out from the furnace of the vertical cold chamber die casting machine and poured into the compression chamber. The metal is injected into the mold by the compression piston, and the surplus metal is pushed out by another piston. Horizontal cold chamber die casting machine is working in the same method as vertical die casting machine, but the movement direction of piston is horizontal. Most modern die casting machines are horizontal. Cold chamber die casting machine can die-casting metal with high melting point, such as copper alloy.
Advantages of cold chamber die casting machine
– Reduced chance of corrosion
– Suitable for casting aluminum, copper and their alloys
– Can be used for manufacturing large parts
Which type of die casting machine you should choose? You can select the machine based on what metals you want to use. For example, if you are going to obtain zinc, tin, and lead castings, you should choose a hot chamber die casting machine, because it’s easy to suffer from corrosion and more suitable for alloys with low melting temperature and proper fluidity. In addition, the high temperature used in casting aluminum and copper alloys will shorten the life of hot chamber machines. On the contrary, cold chamber casting machines are more suited to casting high melting-point metals like aluminum or alloys with a high aluminum content.