Permanent moulds, which are also called chills or chill moulds, are reusable moulds made from hot-working steel or cast iron with lamellar graphite. Depending on the mould material and the geometry of the part, they have a relatively high service life (shape stability). Cavities and undercuts are created using metal cores (so-called slides). Cores can also be made of sand (so-called mixed moulds) and moulds can be used with a lower half made of a metallic material and an upper part made of sand (so-called half moulds).
Casting is performed using gravity pouring. Tilting the mould towards the pouring-hole side can control its filling of the mould.
As a result of the greater thermal conductivity of the metallic ingot mould, the molten aluminium solidifies significantly quicker than during sand casting. This results in a finer and more compact grain structure, which leads to better mechanical properties, weldability and anodisability as well as greater dimensional accuracy than castings of the same alloy produced by sand casting.
Permanent mould casting is particularly well suited for medium to large production runs. The shaped castings find use in the widest range of applications. They can weigh anything from a few grams up to over 60 kg.