Pressocolata (High Pressure Die Casting)

[Lavorazioni a caldo]

Die casting

In die casting liquid metal is injected into a die of the exact shape in which, under pressure, it solidifies. Meltings processed in this manner encompass materials with lower melting points such as tin, lead and zinc alloys, those with mid-range melting points such as aluminium or magnesium and their alloys, up to copper alloys with higher melting points.

In the cold chamber die casting process the melting of the metal to be processed is drawn in portions from a dosing furnace and filled into a casting chamber by means of a ladling device. Afterwards the metal that was poured in is pressed into the die with a hydraulically driven plunger. Due to the fact that the casting chamber does not come into contact with the liquid melting during the entire casting process, thus is cold in contrast to the melting, the term cold chamber process is used. In the hot chamber die casting process the casting chamber is in constant contact with the melting. This chamber is at casting temperature.

Since aluminium alloys and copper alloys react with the steel of the casting chamber, a longer contact of this melt with the tool components leads to erosion and corrosion. For this reason these metals are processed using the cold chamber procedure. In order to be able to guarantee even casting of the dies without premature solidification on thin gage parts as well, the melt is moulded under pressure of 200 300 bar. Due to these high pressure conditions the casting processes take place correspondingly quickly. Even the dies of aluminium castings weighing several kilograms are filled within seconds.

Nowadays approximately 80% of the aluminium castings are produced using the cold chamber die casting procedure.