What is Sand Casting?
Sand casting is one of the oldest forms of metalworking still in widespread use: a process of forming metal parts by pouring molten metal into a cavity shaped by compacted sand. The mould is broken open after the metal has cooled and solidified, revealing the casting inside. The sand is recycled and the process begins again.
It sounds simple. In practice, it is anything but. The choice of sand, binder, and mould construction method determines the surface quality, dimensional accuracy, and structural integrity of everything that comes out. At Maybrey Precision Castings, we have been refining that process for 177 years.
How Sand Casting Works
The process begins with a pattern: a physical model of the casting, made from wood, resin, or metal, built to account for the shrinkage of the metal as it cools. The pattern is pressed into compacted sand to create the mould cavity. Cores, made separately from sand, are set into the mould where hollow sections or internal features are needed.
Once the mould is assembled and any cores are set, molten metal is poured at the correct temperature for the alloy. Pouring too fast or too slow, at the wrong temperature or with poorly designed running and gating, introduces defects. Getting it right consistently is where experience matters.
After solidification and cooling, the mould is broken apart, the casting is knocked out, and the process of fettling begins: removing the running system, cleaning the surface, and inspecting for defects before the casting moves to post-processing.
Materials
Sand casting is one of the few processes that can handle the full range of casting alloys in a single facility. At Maybrey we cast in:
- Grey iron, ductile iron, and SG iron: the workhorses of industrial and heritage casting
- Aluminium alloys: lightweight, corrosion-resistant, essential for aerospace and commercial applications
- Copper-based alloys, including silicon bronze: used in architectural work and sculpture where warmth of colour and long-term patina matter
What It Can Produce
The versatility of sand casting is its defining quality. A single foundry with the right capability can produce a 750 kg iron casting for a heritage restoration project and a 5 kg silicon bronze sculpture for a public art commission, using the same fundamental process.
At Maybrey, we use sand casting to produce components for aerospace and defence, architectural and heritage restoration, art commissions, and commercial engineering: rail, marine, utilities, and buildings products. Castings can be produced as single pieces, small batches, or in ongoing production runs.
Advantages of Sand Casting
- Material versatility: suitable for iron, aluminium, copper-based alloys, and more
- Size range: castings from a few grams to 750 kg in iron, 250 kg in non-ferrous
- Low-volume capability: a single casting is as achievable as a batch of fifty
- Complex geometry: cores and split-line patterns allow for undercuts, hollow sections, and intricate forms
- No minimum order: sand casting does not require the volume commitment that die casting tooling demands
Limitations Worth Knowing
Sand casting produces a rougher surface finish than gravity die or investment casting. For applications where a precise surface finish is critical, post-process work: machining, shot blasting, or grinding, is usually required. At Maybrey, this post-processing is carried out in-house.
Sand Casting at Maybrey
Our sand foundry in Aylesford operates eight Omega sand mixers covering both our iron and aluminium sections. We supply many castings fully machined, heat-treated, and finished, reducing your supply chain to a single point of contact. All production is carried out under ISO 9001:2015 and, for aerospace and defence work, AS9100 Rev D.
Explore our Sand Casting capability
See sand casting in practice: SG Iron Lampposts for Regent's Park