Shell moulding is similar to sand casting, as it uses a mould made of sand to produce components using molten material. However, shell moulding often lends itself to a higher degree of accuracy, as well as faster production rates.
Although shell moulding also uses a sand mould, it does vary to sand casting in a number of ways. Firstly, the sand is mixed with resin, which is then poured over the pattern to create the mould. Secondly, shell moulds are thin-walled, whereas in sand casting, the sand is packed tightly around the pattern to achieve the required shape. However, the moulds in both processes are expendable - it is the pattern that is reused to create multiple moulds.
The mould tool - or 'shell' - comprises two halves, which are then clamped together. The material is then poured or ladled into the mould, where it cools and hardens. Once the material is completely cooled, the mould is then broken open to remove the casting.
Shell moulding is used to create complex shapes from materials such as alloy steel, aluminium alloys, stainless steel, cast iron, carbon steel and copper alloys.
Used to produce
Intricate, complex shapes with a higher degree of accuracy.
Shell moulding is typically used to produce parts from materials such as alloy steel, aluminium alloys, stainless steel, cast iron, carbon steel and copper alloys.
Capable of producing complex shapes.
Higher degree of accuracy compared to sand casting.
Facilitates a quality surface finish.
Can be used to produce parts with thin walls.
More expensive than sand casting due to the type of sand used to create the mould.
There may be some restrictions on the size and weight of components that shell moulding can produce.