Die Casting, Pressure

Pressure die casting uses high pressure to force molten material into a die, where it is held until it cools and solidifies. It is a less passive form of gravity die casting, with two different methods which can be used depending on the material.

Cold chamber pressure die casting - the more manual process of the two - uses an injection piston to create pressure. The molten material is typically ladled into the chamber, before the injection piston forces the material into the die cavity where it is allowed to cool. Cold chamber pressure die casting is suitable for materials which have a high melting point, such as aluminium alloy, zinc and copper.

Hot chamber pressure die casting uses an internal melting pot that is incorporated into the machine. For this reason, it can only be used with materials that have a low melting point, such as lead and magnesium. A gooseneck chamber sits inside the melting pot, which injects the molten metal directly into the die cavity. Once it has cooled and hardened, the die is opened and the components are retrieved.

Pressure die casting results in a faster component turnaround than other casting methods and unlike gravity die casting, it can be used to produce components with thin walls. However, like its gravity counterpart, pressure die casting is a permanent mould casting process, which means that upfront costs for tooling can be very expensive. For this reason, it is best-suited to high-volume production, where the tooling costs can be better offset.