In gravity die casting (permanent mould casting), molten aluminium is poured into a reusable metal mould and fills it under its own weight. Sand casting is similar but uses expendable sand moulds. Low-pressure die casting, a related process, pushes metal up into the mould with gentle gas pressure. These methods fill more slowly than high pressure die casting, so parts have less trapped gas and can be heat treated.
Why it matters when buying
- Typical alloys are LM6, LM25 / A356, LM4 and LM2; choice depends on strength, heat treatment and corrosion needs.
- Iron and other impurities matter more here than in HPDC because these castings often need ductility.
- Foundries use grain refiner and strontium modifier; ask whether the ingot is pre-treated.
- Moulds and tooling cost less than HPDC dies, so gravity casting suits medium volumes and larger parts.
Typical uses
Alloy wheels (usually low pressure), cylinder heads, pump and valve bodies, electrical fittings, marine parts and machine components. Browse alloy ingots.