Abrasive blasting involves propelling an abrasive medium against a workpiece surface at pressure using abrasive blasting equipment that is powered by an air compressor to strip dirt, debris, coatings or rust from a surface without damaging the material. This technique, most often used to prepare surfaces before finishing, was developed as a cost-effective way to replace hand cleaning. As a matter of fact, abrasive blasting can reduce the time spent cleaning and preparing a surface by 25% to 75% and offers better results as it provides a superior surface for bonding when compared to manual techniques.
Because there are many different abrasive blasting techniques and media types (the abrasive material used in the process) this blog will shed light on abrasive blasting equipment, techniques and media, as well as the benefits of this surface cleaning and preparation process.
The Advantages of Abrasive Blasting
As mentioned above, abrasive blasting significantly reduces the time it takes to clean and prepare surfaces, but there are additional advantages as well, such as:
Better adhesion: Paints, powder coatings and other finishes will adhere better to surfaces that are cleaned via abrasive blasting because the process provides a more thorough removal of dirt, grease and rust.
Minimizes damage: Compared to chemical strippers and cleaners, which can damage and deform the substrate of the surface being prepared, abrasive blasting minimizes the risk for damage when the proper media and technique are applied.
Eco-friendly: Abrasive blasting is significantly more environmentally friendly than chemical cleaning as the media do not emit greenhouse gases during the blasting process and many can be reused.
Customized surface profiling: The adhesion of a surface can be controlled by using different sizes or types of blasting media, delivered at different pressures during the surface preparation process. Different coatings and customer specifications may require differing levels of adhesion or finishes, so the ability to customize this is a distinct advantage.
Economic: In addition to saving significant time in labor hours, most of the abrasive media options are reusable, which reduces costs.
Abrasive Blasting Equipment and Techniques
Because there are many different applications, there are many different options available to provide a unique solution for each situation.
However, regardless of the material or the applications, the most common types of abrasive blasting involve the use of basic abrasive blasting equipment, which includes the following components:
Abrasive blast cabinet: The surface or part that is to be treated is placed within the abrasive blast cabinet, sometimes called a blasting machine, used to blast surfaces with the abrasive material at high velocity.
Blast Pot: When blasting in an open air environment, rather than a cabinet, construction related companies will use a blasting pot.
Air compressor: An air compressor is connected to a blasting machine so the air provided by the compressor can propel the abrasive particles onto the surface.
Abrasive blasting nozzles: These are used to focus and accelerate the abrasive stream. Round nozzles are the most common and produce a narrow, accurate stream.
Abrasive media: The abrasive media is the material used to abrade, clean or modify a surface.
Reclaim: For capturing and filtering the used media.
Dust Collector: For minimizing dust that may circulate in the ambient air. Typically in the abrasive blasting process, the surface to be treated is placed within the abrasive blast cabinet and a technician, who must wear protective gear such as gloves, and ear protection adds the blasting media to the blasting machine. When using a blast pot a respirator helmet and suit may also be required. A hose with a specialized abrasive blasting nozzle is attached to the machine and then the technician moves the hose and nozzle in smooth, side-to-side strokes to blast the surface until the desired level of treatment is achieved for the application.
Abrasive Blasting Media
The media used in abrasive blasting will vary from application to application. Media can be grouped into several types, including:
Glass and ceramic: Ceramic grit, crushed glass and glass beads can be used when a softer finish is required, such as on stainless steel surfaces. Glass beads are ideal for cleaning and preparing surfaces without embedding media in the part.
Metal: Steel grit, steel shot and aluminum oxide, are suitable for blasting heavy-duty industrial applications, as well as strong surfaces such as marble.
Natural and Plastic materials: For the treating of very sensitive surfaces, recycled plastic beads, and natural blasting media exist, including crushed walnut shells, ground corn cobs and powder created from apricot, peach and plum pits.
Specialty materials: Sodium bicarbonate can be used to treat surfaces used for food processing equipment or motor rebuilds where residual grit cannot be tolerated. Once the blasted part is dipped into a liquid, the Soda simply dissolves.
Other Blasting Techniques
In addition to abrasive blasting, which uses the media mentioned above, there are a few other blasting techniques, including:
Wet blasting: Wet blasting involves the high-pressure application of water. Water may be used alone or mixed with an abrasive media. It can be used to reduce the dust associated with dry abrasive blasting.
Vacuum blasting: Also a dustless form of blasting, vacuum blasting delivers a soft-touch using a blasting machine equipped with vacuum suction that removes the propelled abrasives and surface contaminants and returns them to the control unit. This also provides a cost-effective way of collecting media for reuse.
Wheel blasting: In this process, a motor-operated blade wheel shoots the abrasives at high speeds at the surface. This method does not use compressed air.
Micro blasting: Also called pencil blasting, micro blasting uses compressed air, nozzles and fine powders for applications that require extreme precision. Micro blasting can also be used for cutting, drilling and deburring.
Abrasive blasting not only provides a cleaner, better prepared surface with excellent adhesion, but it is also a more environmentally friendly and cost-effective method when compared to using chemical cleaners and manual labor. The wide variety of techniques and media means that there is a suitable solution for every surface preparation application. To learn more about abrasive blasting equipment and techniques and how they can improve your finishing operation, contact a representative at HTE, a Tavoron company today.
