Sand Castings
Sand casting pours molten metal into a mould made of compacted sand around a pattern, producing parts from a few kilograms to several tonnes in iron, steel, aluminium and copper alloys. It has low tooling cost and suits prototypes, low volumes and large parts.
What it is
A pattern of the part (with allowances for shrinkage and machining) is pressed into sand to form the mould cavity; cores form internal passages. After pouring and cooling, the sand is broken away and the casting is fettled, shot blasted and inspected.
Green sand suits most iron and aluminium work, while resin-bonded (no-bake) sand gives better accuracy and finish for larger and steel castings.
Typical applications
- Pump and valve bodies
- Machine beds, housings and brackets
- Gearbox casings
- Impellers and manifolds
- Agricultural and construction machinery parts
Suitable materials
- Grey iron (FG 200–300)
- Ductile / SG iron (SG 400/12–700/2)
- Carbon and alloy steel
- Aluminium alloys (LM6, LM25)
- Bronze and brass
Points to consider
- Include machining allowance (typically 2–5 mm) on machined faces.
- Add draft angles (1–3°) and generous radii to help moulding and metal flow.
- Keep wall thickness as uniform as possible to avoid shrinkage defects.
- State whether radiography or other testing is required for critical parts.
Frequently asked questions
When should I choose sand casting?
For low to medium volumes, large or heavy parts, and ferrous alloys, where low tooling cost matters more than surface finish.
How accurate are sand castings?
Typically ISO 8062 CT10–CT13, so critical faces and holes are machined afterwards.
Can sand castings be machined?
Yes. Most sand castings are machined on functional surfaces; allowance is added to the pattern for this.