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What is shot blasting / wheel blasting?
We discuss what shot blasting is, with a focus on a type of shot blasting called wheel blasting, and how it is used.
What is shot blasting?
Shot blasting is a surface treatment, where tiny spheres of material are shot at high speed to remove oxidisation and other dirt or debris against the surface of a workpiece. It does this through what is known as peening, using the mechanism of plasticity/plastic deformation, spreading the substrate and dimpling it. When utilised on components subject to stress, such as gears, crankshafts, or springs, it strengthens them by avoiding the propagation of microcracks in their surface and relieves tensile stresses. Shot blasting is similar to sandblasting/grit blasting, in that material is propelled at a substrate to remove imperfections from its surface, however shot blasting has different applications and characteristics. Shot blasting media is reclaimable and can be used multiple times before it becomes spent (unlike some types of abrasive media), and it is legal in the UK, unlike blasting with sand. The most effective method of shot blasting repeated shapes and components involves the use of a centrifugal wheel and is known as centrifugal blasting, or wheel blasting.
What does the process look like?
For centrifugal blasting, or wheel blasting, the wheel is filled with the shot media and spun to create the necessary velocity. The shot travels from a hopper through a series of pipes and hoses under pneumatic force and is deposited in front of the spinning blades. These blades project the shot into a “blast pattern” which strikes the product that requires treatment. When the shot strikes the surface, it removes contaminants (such as rust, paint, or scale), dimples and peens the surface, and creates a textured finish.
How does shot blasting utilise circular stainless steel media?
There are various choices of abrasive materials to be used when shot blasting, stainless steel shot is commonly used for centrifugal/wheel blasting. Stainless steel is highly durable, resistant to corrosion, and capable of withstanding repeated impacts without significant degradation.
Often in the form of small spherical balls or shot, it has a uniform shape that allows for consistent impact and a high-quality surface finish on the workpiece and will remove surface contaminants without embedding impurities into the surface, which is essential for both aesthetic and functional purposes.
Due to the high durability and wear resistance of stainless steel, the media can be recycled and reused many times, making the process exceptionally cost-effective over extended periods.
After the shot blasting process, the media is typically separated from the debris and contaminants through a recycling system within the blasting machine. The clean media is then collected and reused in subsequent blasting cycles.
What is the difference between shot blasting other surface treatment techniques?
Shot blasting is typically faster and more efficient than some surface treatment techniques, and shot blasting is known for quick turnaround times and fast production. It can also be used on a wide range of materials and surfaces, peens surfaces, and cost-effective when accounting for its recyclable nature. However, shot blasting would not be suitable outside industrial fabrication and production. Other surface treatment techniques, for instance sandblasting (an outdated term, better known as grit blasting or abrasive blasting) would be better suited for residential projects, such as treating masonary.
Choosing surface treatment techniques depends on the specific requirements of the task, including the desired surface finish, material of the workpiece, and the nature of the contaminants to be removed.
What machines do you use for shot blasting?
There are many types of shot blasting machines that you can use. The shot blasting machine typically consists of a blast wheel, a containment area to capture and recycle the shot, and a dust collection system to control and remove any airborne particles, which helps to reduce hazards and improve health and safety. Blasting processes can be significantly improved when using the correct machine for the component. Many of our larger machines are suitable for the shipbuilding and shipyard industries, steel structure companies and OEMs. See our range of shot blasting machines here.
