Sand mold casting is compatible with many materials; however, it is more common for metals. Choosing the right material depends on the casting properties, production volume, etc. The most common materials used in sand casting include:
Aluminium is one of the most commonly used sand casting materials due to its mechanical properties. It has a high strength to weight ratio, low density, corrosion resistance and castability. Common aluminium sand casting alloys include ADC12, AL6061 and A356. Aluminium sand casting requires base sands such as silicochromite and chromite.
Bronze, an alloy of copper and tin, is a common material for sand casting. The sand casting of bronze depends on its different alloys, which are based on the ratio of copper to tin or the presence of other elements such as aluminium, zinc, nickel and iron. Bronze alloys suitable for sand casting include aluminium bronze, manganese bronze and silicon bronze. Each bronze alloy has its own properties. For example, aluminium bronze and manganese bronze have high strength, corrosion resistance, wear resistance and good toughness. Manganese bronze has corrosion resistance, wear resistance and exceptional mechanical properties. Silicon bronze, on the other hand, has good machinability and castability.
Brass is an alloy of copper and zinc which, due to its high elemental content, is resistant to rust and corrosion. Brass does not contain iron or iron oxide. Brass has good electrical conductivity and tensile strength. Brass is therefore a very popular sand casting material for parts that require such properties.
Zinc is a strong material with high hardness, corrosion resistance and castability. In addition, the strength and hardness of zinc makes it easy to produce thinner walled parts after alloying. Zinc is easier to sand cast than aluminium.
Lead was one of the most commonly used materials for sand casting by the Romans. It is heavy and resistant to corrosion. However, it has certain health risks and must be used under strict conditions. Nevertheless, it is suitable for making small and medium-sized parts such as pipe fittings.
Copper is an expensive, strong, heavy material known for its electrical and thermal conductivity. Because copper does not rust and is highly malleable, it is suitable for sand casting, such as plumbing fixtures.
Iron is commonly used in sand casting due to its fluidity and low volumetric/linear shrinkage. However, its poor mechanical properties, high compressive strength and low tensile strength make it unsuitable for parts with complex shapes or asymmetric structures. For example, grey iron castings have excellent castability and machinability; ductile iron castings have good fluidity and high shrinkage; and malleable iron castings have excellent ductility, machinability, toughness and corrosion resistance.
Mild steel has a lower carbon content (0.15% to 0.30%), which gives it greater ductility and malleability. Mild steel is widely used because of its low cost and ease of casting. However, porosity, shrinkage and cracking make it difficult to machine.
Stainless steel’s corrosion resistance, durability and strength make it a popular choice for sand casting. It also has a low coefficient of thermal expansion, which improves precision, high tolerances and dimensional stability. However, it is an expensive metal and its high strength and hardness make parts difficult to eject from sand moulds.
Are you looking for a reputable partner for your parts fabrication and machining projects? Look no further. At PROTO MFG, we specialize in CNC machining and related technologies, including sheet metal fabrication, rapid prototyping, etc. Whether it is a project with a simple design or parts with complex geometries, do not hesitate to contact us today!
