abrasive blasting process
Introduction to abrasive blasting
Generally, abrasive blasting is a method of throwing abrasive with compressed air to remove from or change the surface of a part. Given that many parts have hard to reach areas, abrasive blasting with air can solves many problems with regard to the size and shape of the parts to be blasted. The large variety of applications accounts for the diversity of blasting equipment in use, ranging from small low-powered equipment to large blasting booths including work stations for surface preparation or texturizing. Blasting rooms can be used for very large or welded assemblies such as structural steel, metal equipment framing, or car and truck bodies.
Variety of abrasive blasting media
A large variety of abrasive blasting media are available to accomplish a wide spectrum of tasks. The shape, size, and material of the abrasive used is dependant upon the shape of the product, its base material, and the task to be performed. Many tasks can be accomplished by abrasive blasting, such as stripping of paint and other coatings, cleaning and descaling, derusting, deburring, etching or texturizing.
| Abrasive | Shape | Hardness (MOHS) | Density (lbs/ft3) | # of Uses |
| Sand | Irregular | 5.0-7.0 | 100 | 1 |
| Staurolite | Rounded | 6.5-7.0 | 128-148 | 1 - 5 |
| Garnet | Subangular | 7.0-8.0 | 130-147 | 3 - 10 |
| Olivine | Angular | 6.5-7.0 | 90-109 | 1 |
| Hematite | Semi-round | 6.5-7.0 | 183.5 | 6 - 7 |
| Coal Slag | Angular | 6.0-7.0 | 75-100 | 1 |
| Copper Slag | Angular | 7.0-8.0 | 110 | 1 - many |
| Nickel Slag | Angular | 7.0-8.0 | 110 | 1 |
| Crush Glass | Irregular | 5.5-6.5 | 75 | 1 |
| Steel Grit | Angular | 40-70 HRc | 260 | 100 - 1500 |
| Alum. Oxide | Irregular | 9.0 | 120-131 | 3 - 20 |
| Source: Michigan State University | ||||
Styles of abrasive blasting machines
The variety of styles in abrasive blasting machines is so great it is beyond the scope of this document. Though, in general, they all have delivery systems and some form of controls. Except for portable systems, blasting equipment have enclosures, part holding mechanism, dust collector, and a media recovery system. The two most commonly used enclosures are abrasive cabinets and abrasive blasting rooms. The delivery systems fall into 3 main categories using compressed air in each of them.
- pressurised projection systems
- Both abrasive pot and the air / abrasive mixing chamber are under the same pressure, which sweeps abrasive along in the blast hose.
- suction systems
- Compressed air injected in the gun through a nozzle creates a partial vacuum that sucks a mix of air and abrasive from the pot.
- gravity systems
- Abrasive enters the mixing chamber by gravity and is then pushed by compressed air into the nozzle.
In abrasive blasting many types of nozzle are available for use with different shapes to control to abrasive pattern, also, different diameters that change abrasive velocity and cleaning efficiency. In addition, different nozzles are used dependant upon the desired affect, the media used, and the base material of the part. Air supply has to be adapted to meet the needs of the application. The compressor power as well as length and diameter of air and abrasive hoses have to be adjusted to achieve the desired result. Abrasive blasting with compressed air many times is not as economical as airless blasting systems, but sometimes it is the best way to get the job done.
The efficiency of abrasive blasting makes it the first choice for many jobs today. For more information on abrasive blasting, feel free to contact us at any time. For details on our specific capabilities, visit the abrasive blasting services page.
