What is abrasive grit blasting

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Abrasive grit blasting is quite a common process used in manufacturing companies nowadays. However, unlike machining or welding, which are easily understood, the term abrasive grit blasting needs a formal definition in order to avoid confusion. Put simply, I would like to define abrasive grit blasting as the process of modifying a surface by propelling abrasive material against it, usually by force. This is the simplest definition of abrasive grit blasting.

Abrasive grit blasting also goes under different names. Commonly used terms of abrasive grit blasting include grit blasting, sand blasting, shot blasting, vapor blasting and abrasive blasting. However, some of these terms are not exactly interchangeable and in fact some of these commonly used terms for abrasive grit blasting do mean different variations of the basic process.

When used appropriately, the process of abrasive grit blasting as defined above is actually a surface modification process. It modifies a surface in that the process can be used to clean surface contaminants such as dirt, old paint, etc and thus expose a clean surface; it can also be used to modify or change the roughness of a surface by making it rougher or alter the profile of a surface.

Abrasive grit blasting is sometimes used as the only surface modification process as in the case of cleaning graffiti out of elaborate carved stone figures or of cleaning the paint out of wooden structures or cleaning tombstones. Abrasive grit blasting is many times used as a surface preparation step for subsequent coating or finishing operations. In some cases, abrasive grit blasting is used to remove or strip an existing coating and then the same process using a different set of parameters is used to prepare the surface for re-application of fresh coating. This is the case in strip and re-coat operations of some industrial components.

The second part of our definition of abrasive grit blasting has to do with propelling the abrasive material using some sort of force. The force is generated either by suction, pressure or both. And the carrier of the media can be either air, water or other liquids or both. Herein lies the opportunity for various permutations and combinations leading to different types of the process notwithstanding the variations of materials used.

There are two basic categories here: one is portable blasting and the other is stationary blasting. As the name indicates, portable blasting is generally used for on-site work and stationary grit blasting is done in a stationary cabinet or blast room. In the former, the abrasive grit is not recycled, whereas in the latter, the abrasive grit is recycled and re-enters the blast cabinet, thus saving in media usage.

A particular terminology subset of the abrasive blasting process is pencil blasting, wherein a fine nozzle with a fine but powerful abrasive is used to etch on glass and is used by artists in the decorating industry.