Shot blasting is simply a process of using high-pressure air to forcefully propel a small steel shot against a metal surface in order to clean it. The process usually works by propelling abrasive media material with high centrifugal or mechanical force, and it usually occurs in an enclosed cabinet, blast room, or enclosure.
The steel shot or steel grit (used for blasting) is usually spherical and made of hardened steel, whereas the surface that needs to be cleaned/blasted can be made of any material but is most commonly metal.
The shot blasting process is different from grit blasting as it can have a peening effect on the surface being blasted, which can actually increase the compressive strength of that surface.
If you are interested in knowing more about shot blasting, how a shot blaster works, what blasting materials it uses, what its benefits are over other abrasive blasting methods and other most frequently asked questions about shot blasting, let’s take a look…
What is Shot Blasting Used for?
Shot blasting is commonly used to clean metal surfaces in preparation for painting or other surface treatments, especially when the surface is very large and difficult to prepare.
These types of surfaces will ideally need a stronger application force (applied by a shot blaster) along with denser media materials for preparation.
The shot blasting centrifugal abrasion treatment is also sometimes required to create a particular finish on metal surfaces that need to be used in large-scale production.
For example, a rough, textured finish is often required on handrails or other objects that will be handled frequently, as a smooth finish can become slippery when wet.
Another example of this might be creating a textured surface on a metal sheet that needs to be used for anti-slip flooring.
Shot blasting can also be used to remove rust or other rough surface contaminants from metal surfaces like car and truck frames that need to be restored or the steel containers that are being recycled.
When conducted properly, shot blasting is an efficient way to remove these types of contaminants without causing any damage to the metal surface beneath.
What Abrasive Media is Used in Shot Blasting?
The abrasive media material you choose is the key factor that decides the success of the abrasion blasting process. These materials are available in different forms that range from mineral, organic, ceramic, and plastic to metal-based.
Depending on the application, some of the most common media materials used in shot blasting include:
1- Steel shot and steel grit:
Steel shot is spherical, while steel grit has an angular shape. These are the best media materials most commonly used for heavy-duty applications.
When deciding between shot and grit, consider that round-shaped media particles are less abrasive than angular shapes.
2- Aluminum oxide:
Aluminum oxide is also an excellent media because it’s reusable and low-cost. Since it’s hard, it’s also ideal for surfaces that need fine polishing.
3- Glass beads:
Glass beads are soft abrasive media that are made from soda lime. These are generally used for blasting soft surfaces.
Besides the above, a few more abrasive media are being used in the blasting process, which includes:
- Corn cobs
- Black walnut shells
- Staurolite (mineral-based media)
- Silicon carbide (hardest abrasive blasting material)
When choosing the suitable material for the project, it’s essential to look at the hardness of the surface to be blasted, along with the density, shape, and size of the media used.
What’s the Difference between Shot Blasting and Sandblasting?
The key difference between shot blasting and grit blasting (or sandblasting) lies in the aggressiveness of the techniques and the application process.
Since the shot blasting process uses high-pressure air and centrifugal force to blast abrasive particles, it is relatively more aggressive than grit blasting.
Sandblasting or grit blasting, on the other hand, generally uses a lower-pressure stream of air to blast sand media at the surface for paint removal or preparation.
Unlike shot blasting (which cleans the parts), grit blasting acts as a protective treatment that helps in smoothening the parts.
Also, the shot blasting method uses a different pressurizing system than sandblasting. This equipment is similar to a spinning wheel, which centrifugally accelerates the shot materials to blast them against a surface.
Other Types of Abrasive Blasting Methods Used for Surface Preparation
Besides shot blasting and sandblasting, a few other types of abrasive blasting processes can be used for cleaning and surface preparation, depending on the application.
Not all of them are as common as the two methods mentioned above, but they can be helpful in specific cases. These include:
- Wet blasting
- Bristle blasting
- Dry-ice blasting
- Vacuum blasting
- Pencil blasting (also called micro-blasting)
- Centrifugal blasting (also referred to as wheel blasting)
The Bottom Line
As you can see, a wide variety of abrasive blasting methods and media materials are available. Choosing one best suited to your needs is crucial to the project’s success.
If you have questions about exactly what system to choose or need help choosing the right surface preparation equipment, it’s good to get in touch with experts and professionals. They can help and guide you in making the best choices for your specific application needs.
Jack Luis is a semi-retired painter who loved painting his clients’ ideas on their walls.
He had worked as a painter for over a decade serving customers in areas such as Charleston, Mount Pleasant, Beaufort, and Georgetown, SC (South Carolina). Today in his free time, he likes to read and write about the newer techniques implemented in his profession. You may read more about him here or get in touch with him here.