What is die casting?

Some of us may know that die casting is a manufacturing process for producing metal parts by forcing molten metal under high pressure into a die casting mold. That is to obtain the idea shape with designed dimension and surface treatment, generally speaking, these die casting mold are created with hardened tool steel that have been previously machined to the net shape or near net shape of the die cast parts or components.

The die casting process usually produces parts using primarily non-ferrous metals, such as aluminum, zinc, copper, and magnesium. It is widely used in automotive, medical, agriculture, electronics, lighting, and other related industries.

Generally the die casting process can be divided into two different categories:

• Hot Chamber Die Casting
• Cold Chamber Die Casting

Hot Chamber Die Casting is the process where the metal injection system is immersed in pool of molten metal hence the name.  The furnace is attached to the machine via a feeding system called a gooseneck.  As the cycle begins the piston will retracts, which allows the molten metal to fill the “gooseneck” from a port in the injection cylinder. As the plunger move downwards, it seals the port and forces the molten metal through the gooseneck and nozzle into the die.  Once the metal solidifies, the plunger will pull upwards.  Afterwards, the die will open and the part is ejected.  The advantage this process its short cycle time as it does not require metal to be transported from a separate furnace.  Unfortunately, this die casting process is only suitable for alloys that do not attack the injection cylinder such as zinc, magnesium and copper.

Cold Chamber Die Casting is the process of using a ladle to transport the molten metal from the holding furnace into the unheated shot chamber or injection cylinder.  This metal is then shot into the die by using a hydraulic piston.  The main disadvantage of this process is that it is relatively slower compared to the Hot Chamber Die Casting process.  However, this process is primarily used for manufacturing aluminum parts as molten aluminum alloys have a tendency to attack and erode the metal cylinders, plungers and dies greatly shortening their tool life.

The main difference between cold-chamber die casting and hot-chamber die casting manufacture is that in the cold-chamber process the molten metal for the casting is introduced to the shot chamber from an external source, while in the hot chamber process the source of molten material is attached to the machine. In the hot-chamber process, certain machine apparatus is always in contact with molten metal. For this reason, higher melting point materials will create a problem for the machinery in a hot-chamber metal casting setup. Since the liquid metal is brought in from an outside source, the die casting machinery is able to stay much cooler in a cold-chamber process.

The above mentioned is a brief introduction about die casting manufacturing. If you have any inquiry, please don’t hesitate to contact us!