Aluminium is cast by several main methods. The right choice depends on the production volume, the size and complexity of the part, the dimensional accuracy and the properties required — and each method has its own suitable alloys.
Sand casting
The melt is poured into a sand mould. Tooling costs are low, so it suits large parts, small volumes and prototypes, but dimensional accuracy and surface quality are lower. Common alloys: LM4, LM27, A356.
Gravity die casting (permanent metal mould)
The melt fills a metal mould under its own weight. Faster solidification gives a finer structure and better mechanical properties than sand casting, and it is economical for medium volumes. Common alloys: A356, AS7G03, AlSi9Mg, LM6.
Low-pressure die casting
The melt is pushed up into the mould from below by low gas pressure; the slow, controlled filling produces sound parts with little porosity. It is the main method for making aluminium wheels from A356.
High-pressure die casting
For very high volumes and precise thin-walled parts, using alloys such as ADC12, A380 and A413. See our complete guide to aluminium die casting.
Summary
To choose an alloy for your casting method, use the Almas alloy finder, and get to know the common casting defects.