Steel shots and aluminum oxide abrasives such as brown fused aluminum oxide and white alox, could all be used for surface treatment of steels. What are the features of steel shots, compared with aluminum oxide abrasives?

Particle Shape

Steel shots are round, while aluminum oxide abrasives are angular. Rounded abrasive particles of steel shots produce a peened surface, whereas angular or irregular shaped abrasive particles of white fused alumina and brown aluminum oxide produce an etched or angular surface profile. Selecting the right particle shape to produce the required profile and texture for the job at hand can impact productivity and performance of the coating applied.

Particle Weight

Different blasting abrasives have different densities. Density of blasting media directly affects impact performance. For a given impact velocity and particle shape, the weight (mass) of the particle determines the shape and the depth of the profile produced.

The density of steel shots is about 7.8g per cubic centimeter, and the density of aluminum oxide abrasives is about 3.9g per cubic centimeter. Because steel abrasives have approximately 1-1/2 to 2-1/2 times the density of nonmetallic abrasive, steel abrasives create more impact for a given particle size. Smaller steel abrasive particles will produce the same impact value as nonmetallic particles 1-1/2 to 2-1/2 times larger. With the smaller steel abrasive there are more abrasive particles impacting the surface per unit time, which means faster cleaning rates.

Particle Size

Abrasive particle size influences two primary functions of blast cleaning, rate of cleaning and profile. Decreasing particle size may increase cleaning rate because more particles are impacting the surface per unit time. Increasing abrasive size may be necessary to increase profile and/ or to remove heavy coatings.

Particle Hardness

lt is generally believed that the harder an abrasive, the better it will perform on difficult to clean areas.

Aluminum oxide abrasives rank behind diamond and silicon carbide in terms of hardness. It’s mosh hardness is as high as 9. It has the ability to provide a deep anchor pattern or etch in applications when surface preparation is critical, such as surface profiling for subsequent protective coatings.

Dust Generation

Metallic abrasives do not break down on impact like conventional nonmetallic abrasive products. Consequently, there is considerably less dust and waste generated during the blasting process. Low dust levels mean better visibility, faster cleaning, increased productivity and shorter clean-ups, saving time and labor and disposal costs.