Blasting and Peening MediaIn air or wheel blast industries, the terms abrasives and media are often used intercha
Blasting and Peening Media
In air or wheel blast industries, the terms abrasives and media are often used interchangeably. Most abrasive blast applications will fall into these categories: finishing, cleaning, removing, surface profiling, peening, and blending.
Abrasive media is classified, or sized, based on mesh screens ranging from 8 to 400. The higher the mesh size number, the smaller or finer the grain. The bulk density of blast media will range from an average of 50/lbs. for plastic media up to approximately 300/lbs. per cubic foot for steel shot.
The application purpose and material being worked on will determine the type of blast media. The compositions and shape of the media play into that choice.
Angular abrasives possess cutting ability in order to provide profiling, cleaning and removal. There is a broad range of angular media choices, from single-use, disposable media to metallic blast media offering long life cycles.
Spherical media will yield decorative finishes, peening, cleaning and blending. There is a wide-range of spherical media, all offering multiple uses and long life cycles.
The type of blasting equipment will help determine, or eliminate, the type of abrasive that can be used. Most air blast cabinets, which use pneumatic recovery systems, are limited to the smaller mesh size ranges of metallic media. Wheel blast machines utilize the density of metallic media to provide the energy for finishing.
Most blast media have some degree of recyclability, or multiple turns, before it is used up. Effective recovery systems will help maximize the amount of turns and the investment in blasting media. All blast media has a life cycle and eventually breaks down. Maintaining a working mix, by adding new abrasive media to the current batch, is very important to obtain consistent results.
Single-use media is a popular choice for portable blasting operations where there is no recovery system. The media is useful for one impact, then discarded.
Peening is a term in the industry that can describe two different applications. Both applications will use spherical blast media. Generic “peening” is the appearance achieved from the spherical shape of the media. It can also help reduce porosity or friction and provide the surface finish to improve lubricity. The mechanical version of “peening” is a controlled blast procedure that will use the spherical media to strengthen, add fatigue resistance, and improve wear properties. Specification for mechanical peening dictates the PSI or intensity of the blast media, duration of the blast, and the specific size of the media needed to obtain the desired results.
A majority of abrasive blast media is used to remove a coating, improve an appearance, or provide a profile for new coatings.