How to Choose the Right Abrasive Media
Abrasives are an extremely important, yet often overlooked component of material preparation and finishing applications. By taking the time to select the right abrasive, surface preparation jobs can be completed faster while using a minimum volume of abrasives. A well-informed decision can translate into substantial increases in profits while also providing a high-quality finished product.
Types of Abrasive Blasting Media
The best abrasive for an application will depend on the parameters of the project, the surface conditions of the substrate, and your anticipated outcome. Dawson-Macdonald offers an extensive selection of abrasives, each specially formulated the meet the unique needs of specific project types. The following abrasive blasting media guide will help you through the abrasive selection process.
Aluminum oxide is a virgin-fused abrasive available in both brown and white. This aggressive abrasive exhibits exceptional strength and hardness and is capable of blasting virtually any type of surface. Its composition, density, and physical attributes make it well-suited for both wet and dry blasting processes.
Aluminum oxide abrasives are ideal for the following types of applications:
- Abrasive blasting
- Refractory coating
Glass bead abrasives consist of small, spherical, and uniform beads manufactured from chemically inert materials. These versatile and recyclable beads provide a smooth, bright finish, making them perfect for adding aesthetic appeal to a surface. They are capable of cleaning, peening, and finishing without removing a significant amount of surface material.
Glass beads are typically used for:
- Applications requiring a soft, bright finish
- Stainless steel applications
- Blasting, cleaning, and light deburring
Silicon carbide is one of the hardest types of abrasive media available. The hardness of the particles enables significantly shorter blast times compared with softer media. This synthetic abrasive is available in a variety of colors and purities.
Silicon carbide abrasives are suitable for:
- Challenging surface finish applications that need an extremely aggressive abrasive
- Applications requiring fast cutting action
- Surface cleaning and polishing
Steel Shot & Steel Grit
Steel shot and steel grit are two types of metallic abrasives that differ in shape. Steel shot particles are spherical, enabling a smoother, more uniform surface finish. In contrast, steel grit particles have random, angular shapes that provide an etching or eroding effect. Both steel shot and steel grit abrasives are dense, durable, and recyclable.
Steel shot and steel grit media are used for:
- Texturizing surfaces to prepare them for coating
- Heat treatment removal
- Paint removal
Walnut shell abrasive is an economical and biodegradable option derived from natural materials. This abrasive is soft yet durable, making it perfect for removing paint or rust without damaging the substrate surface. It is generally used on softer substrates (wood, plastic, aluminum, etc.) since it is milder than most other abrasive options.
Common uses of walnut shell abrasives include:
- Polishing soft metals, wood, plastic, stone, and fiberglass
- Sensitive applications requiring a moderately aggressive abrasive
- Delicate cleaning, coating removal, and deflashing
Our ceramic bead abrasives are available in two types: Zirshot and Zirblast. Both are recyclable, high-density abrasives that generate very little dust during the blasting process. They can be used with a wide variety of substrates, including steel, aluminum, copper, brass, and plastics.
Ceramic bead abrasives are commonly used for:
- Impact surface treatments
- High-performance applications
- Contamination-sensitive applications
- Shot peening
Corn cob is one of the softest natural abrasives available, making it safe and effective for delicate substrates. This organic abrasive is non-toxic, biodegradable, and environmentally friendly.
Corn cob abrasive applications include:
- Cleaning, deburring, burnishing, and polishing of delicate parts and soft substrates, such as precious metals, wood, fiberglass, and plastics
- Blasting and tumbling
- Applications where no pitting, marring, or etching is desired
Garnet is a hard, durable, and high-density abrasive that provides a clean-edge quality. This natural, non-ferrous abrasive is environmentally safe and produces less dust than many other abrasives. It is also highly impact-resistant and can be recycled several times.
Garnet abrasives are great for:
- General-purpose surface preparation
- Water jet cutting applications
- High-performance applications requiring a fast-cutting abrasive
- Removing thick coatings from substrates
Plastic abrasives are soft yet durable, making them an excellent option for cleaning or removing coatings from metals and other substrates without marring or pitting. These abrasives are preferred for many applications since they leave no residual deposits and are highly cost-effective.
Plastic abrasive medias are well-suited for:
- Applications requiring a silica-free abrasive
- Mold cleaning
- Blasting of plastic parts
- Paint removal, deflashing, and surface preparation applications
Additional Factors to Keep in Mind
When choosing an abrasive, it is important to consider how the unique properties of each medium will affect the surface profile and finish of the final product. Abrasive properties that impact profile depth include:
- Size. While larger-sized particles can create deeper indentations, blasting them will result in fewer surface impacts than what could be achieved by an equivalent volume of smaller particles. Small particles provide a faster cleaning rate and better coverage, resulting in a more uniform surface profile. As a rule, try to use the smallest possible particle size that will provide the required surface preparation characteristics.
- Density. Since high-density particles impart more kinetic energy to the blasted surface, they are generally capable of cleaning faster and more thoroughly with a lower application rate than low-density particles. High-density particles also deform less and have the potential to last longer.
- Hardness. In general, harder particles will impart deeper profiles onto surfaces and will also remove materials more quickly. Hard abrasives are highly effective for removing thick coatings, rust, and corrosion. Softer abrasives, on the other hand, take longer to remove materials but provide finer finishes without anchor patterns. Soft abrasives are ideal for removing thin coatings or cleaning grease and grime.
- Shape. The shape of a particle will influence its ability to remove coatings or contaminants. Abrasive particle shapes are classified as angular, sub-angular, sub-rounded, and rounded. Particles with an angular shape produce anchor patterns on the substrate surface and are effective at removing soft, pliable coatings and rust. In contrast, rounder particles produce a more uniform, peened surface, and are better suited for removing hard, brittle coatings and mill scale.
- Velocity. In addition to particle characteristics, another important factor to consider is the velocity of the abrasive media as it impacts the substrate surface. By increasing the velocity, the abrasive will be more capable of imparting deeper profiles onto the surface. Once you have selected an abrasive with the appropriate physical properties, the depth profile can be fine-tuned in the field by adjusting the blasting pressure.
Let the Dawson-Macdonald Team Help You Select the Right Media
Selecting the right abrasive media can have a substantial impact on both the cost of the project and the quality of the final product. With more than 90 years of experience in our industry, Dawson-Macdonald has the expertise to provide highly effective abrasive solutions for a broad range of surface finishing applications. With our diverse blasting media options, we are prepared to guide you through the selection process to identify a solution that will accommodate your project’s specific requirements.