Dirty, oxidised or unfinished materials are undesirable for all sorts of reasons.
For example, a material that is covered in scale, dirt and other debris isn’t easy on the eye, and oxidised materials can pose serious problems during the fabrication process (e.g. welding or machining).
Though you could apply a fresh coating to the surface without cleaning it, this is likely to cause a lack of adhesion. And any sharp burrs and edges could cause lacerations.
With that said, it’s always worth cleaning the material beforehand – whether it be a quick wipe down with a rag and suitable cleaning solution or shot blasting.
Intrigued by how shot blasting works? Let’s take a look…
What is shot blasting?
Shot blasting and sandblasting are often used interchangeably. Though they belong to the same family of abrasive blasting processes, it’s important to note they are two different processes.
Put simply, shot blasting is a mechanical cleaning process employed by almost every industry that uses metal (i.e. aerospace, automotive, foundry, rail, and shipbuilding).
It removes oxides and other remnants and polishes surfaces using spheres of material, otherwise known as abrasive shots or abrasive media. A centrifugal wheel is used for propulsion.
Sandblasting, on the other hand, uses grains of sand that are propelled at the surface using compressed air.
How does it work?
Exactly as its name suggests, shot blasting is where an abrasive media (or shot) is blasted against the surface to remove contaminants and improve its appearance.
The type of abrasive shot used is dependent on the application and the material of the surface that needs shot blasting. The size and hardness of the shot will also dictate how much surface removal will occur, which is why it pays to choose carefully.
The propulsion method is another important part of the process as it determines the speed at which the shot will be fired at the surface.
In most cases, abrasive media is propelled using centrifugal force. This means it will be unloaded into a centrifugal wheel and – once it has been accelerated to the desired velocity – released from the wheel, into a shot blasting machine. Then the operator will direct the flow of the shot media to clean or smooth the surface.
Though it typically depends on the type of shot blasting equipment used, some have a recovery system that will collect the material that’s produced after firing the shot, returning it to the propelling device so it can be reused.
What materials can be shot blasted?
This is something we get asked a lot here at SFEG, and the truth is many materials can be cleaned using the shot blasting technique:
- Carbon steel
- Cast iron
- Ceramics
- Concrete
- Copper
- Stainless steel
- Titanium
As for the material of the shot, you have the choice of reusable and expendable abrasives.
Expendable abrasives are typically used for open blasting where the media is not recovered. Examples include iron silicate, Abrablast, and garnet, to name just a few.
Reusable abrasives, such as steel grit, aluminium oxide, glass bead and steel shot, are the economical choice for (closed) shot blasting in blasting cabinets.
Is it safe?
Though we might be slightly biased as surface finishing equipment suppliers – here at SFEG – we strongly believe shot blasting is one of the most effective and safest ways to prepare a surface for a new coating.
Some processes, such as sandblasting, produce a lot of dust. If the appropriate safety measures aren’t in place, these dangerous particles can be unintentionally inhaled, resulting in breathing problems for operators.
The good news is that the media used for shot blasting doesn’t create much dust, making it safer for those working in the blasting environment.
However, you still need to make sure that you acquire the highest quality shot blasting equipment and accessories.
No matter what industry you work in, and the surface that needs shot blasting, you’ll find everything from blast pots to abrasive media and PPE on our website.
To learn more about the process itself or the products we supply at SFEG, don’t hesitate to get in touch.
