Abrasive blasting is also known as grit blasting or sandblasting. It is the process by which particles are propelled against a surface at high pressure. The method involves the use of a pressurized liquid and blasting media.
The pressurized fluid pushes the abrasive media against the surface at high pressure thus cleaning it. Apart from cleaning, abrasive blasting is also used in roughening, smoothening, and shaping surfaces.
The most common abrasive media is sand while air is the most widely used propellant.
Abrasive blasting process.
Most abrasive systems consist of a fluid container, a propeller, and a nozzle. The container holds the pressurized fluid. The propeller forces the abrasive media towards the target surface, and the nozzle controls the pressure with which the media leaves the fluid container.
Depending on the propelling method used, we can have different categories of abrasive blasting:
1. wet blasting
Wet blasting systems use compressed air, abrasive media, and water. The use of water brings about several advantages
Water lubricates the abrasive media thus producing a smoother surface. Water also causes the abrasive material to flow evenly over the surface. The effect of this is a uniform surface. The use of water also minimises physical damage to the surface.
Various abrasive media can be used in wet blasting depending on the desired surface.
2. Wheel blasting
In wheel blasting, there is no propellant used. The method uses a rotating wheel. As the wheel rotates at high speed, it develops centrifugal force. The force propels the abrasive media towards the target surface. Metallic abrasives are the most widely used media in abrasive blasting.
Wheel blasting has some advantages. It can blast large surfaces within a short time. It is also less costly for large surfaces compared to fluid based propellants.
The main disadvantage of wheel blasting is that it can damage softer services. This is because the abrasive media are propelled at a very high velocity.
3. Micro-abrasive blasting
It is also known as precision blasting or pencil blasting. Micro-abrasive blasting uses narrow nozzles to deliver micron-sized abrasive media to a part of a surface. The small nozzles help in intensifying and focusing the stream of abrasive media.
The main advantage of pencil blasting is its accuracy. Furthermore, it can be used in cleaning tight fissures.
Abrasive blasting processes can also be classified according to the media used. Different abrasive media are used to achieve different effects. For example, glass beads produce a smoother surface than sand.
Another factor that affects the choice of abrasive media is reusability. Synthetic abrasives can be reclaimed and recycled. Cost and availability can also influence the selection of abrasive media.
Abrasive blasting leads to air and noise pollution. For example, sandblasting releases silica dust into the air. The surfaces being cleaned might also release toxic materials such as lead and copper.
These materials have adverse effects on the body when inhaled. Silica causes breathing difficulties, lung cancer, and silicosis. Copper and lead damage the lungs.
Workers’ safety should be a priority during abrasive blasting. Find out more here: http://vacublast.com.au. The exposure to toxic materials should be minimized or eliminated altogether.