In this third blog on foundry tools and equipment, we turn our attention to the shot blasting machine.
As we’ve explored in a previous blog, shot blasting is a popular finishing technique used in various industries. At Haworth Castings, we use shot blasting to:
clean the parts and enhance the surface texture
remove any small surface particles (such as sand)
prepare the surface for painting
restore the colour of the metal after certain treatments
Shot blasting is usually carried out following removal of the casting from the sand mould. It is also sometimes used after heat treatment to improve the surface finish.
A popular finishing technique
Haworth Castings invested in a new shot blasting machine around three years ago. This large machine has an enclosed cabinet with a rotating turntable.
During the shot blasting process, the casting is placed on the turntable in the cabinet and the doors closed. Safety locks are fitted to the machine to ensure that the doors are not opened during operation.
Small stainless-steel balls are accelerated towards the casting at high speed and at different angles using a series of rotating impellers.
Servicing the shot blasting machine
The machine needs regular servicing as the parts erode very quickly due to the high impact nature of shot blasting. Hard-wearing steel alloy plates are used to reduce the amount of wear, but these still need to be replaced relatively regularly – depending on the frequency of use.
In addition to the large shot blasting machine, we also have a small hand-held shot blaster. This is particularly useful when we need to clean or prepare one side of the casting rather than the whole work piece.