Die casting
Die casting is a casting process where molten metal is forced under high pressure into a steel mold. The mold is under extreme cyclic loading: molten metal, high pressure, and rapid cooling – therefore hot work tool steels with high hot strength are needed.
What die casting is
In die casting, molten metal – usually aluminum, zinc, or magnesium – is forced with very high pressure into a permanent steel mold. The mold fills in fractions of a second and solidifies under pressure.
What this means for the mold
Die casting molds experience the most brutal thermal shock a tool can know: molten metal at over 600 °C hits the steel surface, then the mold is cooled. Add mechanical pressure and erosion from the incoming metal. This cyclic loading creates heat checks – fine crack networks on the mold surface.
The two processes
In the hot chamber process, the injection chamber sits in the molten metal (low melting alloys like zinc). In the cold chamber process, the metal is metered into the chamber from outside (aluminum, magnesium) because it would attack the machine parts.
Material requirements
Die casting molds need hot work tool steel with high hot strength, good toughness at temperature, and resistance to heat checking – typically 1.2343 and 1.2344.