How to Select the right blast media


What Finish Quality Do You Need?

Factors that influence your choice of abrasive include the specified surface profile and quality of finish. Various types of abrasive offer the ability to produce a range of profiles, but not all will guarantee high standards of surface cleanliness. In comparison to relatively soft slags, tougher abrasives that don't easily break down in use will reduce the risk of embedment within the profile and facilitate a cleaner surface.

Particle Size

The ideal abrasive particle size is one that has the largest particle of an equal size to the thickness of the surface coating to be removed. Where the abrasive particle size is larger than the surface coating a reduction in hit rate of particles reduced require more abrasive to remove the coating. Larger abrasive also fills the pot and can lead to shorter blasting time and lower productivity as the blasting operator will require to stop and refill more often than the use of an optimally sized abrasive.

Particle mesh size is the number of holes in a 1"-square screen. As the mesh number gets larger, the number of holes per inch increases, the size of each individual hole decreases, and the media becomes finer. Grit refers to coarseness; the lower the number, the coarser the grit.

Particle Strength

Strength of the abrasive particles determines the durability and therefore the recyclability of the abrasive media. Stronger abrasive grains will convert more of the pressure into energy when it impacts the blasting surface producing a faster effect on removal of the coating. Weaker or softer abrasives grains disintegrate on contact lowering their effectiveness and also generating more environmental dust. Particle friability, or the material’s ability to fracture or break apart upon impact with a hard surface is another factor. Blast media particles that break apart disperse the energy of the impact and are generally less aggressive and “non damaging.”

Particle Shape

The Abrasive particle shape will determine your cutting speed and also the shape of your profile. A sub-angular particle will remove coatings and mill scale faster than round particles. If a particle is too angular it will likely embed in the surface and could become impregnated. Round abrasives are used for peening.

What are the health and safety factors?

In addition, the health and safety of blast cleaning operators should be high on the list of priorities during abrasive selection. Tougher abrasives that don't easily break down produce lower dust levels, giving the operator better visibility and producing a safer working environment. Abrasives containing high levels of free silica or traces of heavy metals such as beryllium may be hazardous to health. (Consult material safety data sheets and be aware of disposal regulations governing any abrasive you consider.)

What are your site or facility requirements?

When selecting your abrasive, evaluate site conditions. For instance, abrasives that produce high dust levels may not be the best sandblasting media when working within confined spaces.

Also, in cases where there is limited access for removal of spent abrasive, a product offering low consumption rates would be most appropriate.

 

 

 

Media Types


Media

Description

Used for

Hardness (Mohs)

Shape

Soda

Soda abrasive is from baking soda or bicarbonate of soda. It offers non-destructive cleaning and is very popularly used by operators.

It is used to remove rust from metals without causing depression or damaging the metal beneath the rough surface. Has the added benefit of neutralizes orders such as smoke, mold, skunk etc. during cleaning, restoration, and remediation.

2.5

Angular

Coal Slag (alumina silicate)

It is a dispensable abrasive which is a by-product of coal-fired electric power generation plants. It has less dust compared to Copper Slag.

It is often used in open blasting operations in the oil- and shipyard industry and other metal surface treatments.

6-7

Angular

Aluminum Oxide Grit

An extremely sharp, long-lasting blasting abrasive that can be recycled many times. It is available in 99.5% pure white grade and commonly standard brown.

Aluminum Oxide Grit is often used in surface treatments and preparations.

8-9

Angular

Crushed Glass Grit

Crushed Glass Grit is made of 100% recycled glass beads and is eco- and health friendly as it eliminates the presence of airborne carcinogens. It is non-toxic and non-hazardous.

This is used in profiling and removal of coatings and surface contamination and can be used around water.

5-6

Angular

Steel Grit

It is softer than Aluminum Oxide Grit but still has a very high hardness quality. It has very fast stripping action and shot-peening applications.

It is commonly used in cleaning, etching, and surface preparations.

40-65 HRC

Angular

Media

Description

Used for

Hardness (Mohs)

Shape

Glass Beads

Glass Beads are manufactured into preformed ball shapes, which are very effective in leaving very smooth surfaces. It produces a super smooth and brighter finish compared to angular abrasives. Glass Beads can be recycled approximately up to 30 times.

Commonly used for automotive restoration, stainless steel fabrication, polishing of castings, and light deburring of metal molds and parts.

6-6

Round

Steel Shot

Steel Shot is manufactured into a spherical pellet-type abrasive made from carbon steel. It often produces a very smooth surface after use.

Steel shot abrasive is often used in cleaning and polishing metal surfaces and parts in automotive, aerospace, construction, foundry, shipbuilding, rail, and more.

40-51 HRC

Spherical

Corn Cob Grit

Corn Cob Grit is an organic, soft, and natural abrasive from hard cob. It is tumbling and absorbent that dries surfaces. Corn cob grit is non-toxic and safe for operators.

It is best used on wood surfaces and does not create any damage on the treated surface. It is used on oily and moist surfaces that quickly absorb it while finishing rough parts.

4-4.5

Ground, Angular shape

Walnut Shell Grit

It is a very versatile soft abrasive, organic, and biodegradable. Same as corn cob, it is non-toxic and imposes no hazard to health.

Best used in stripping and cleaning delicate surfaces and parts, Walnut Shell Grit provides effective applications such as cleaning hardwoods and aircraft and automotive stripping.

4.5-5

Angular

Garnet

Garnet is a natural silicate mineral deposit. It has a high stripping rate, very low dust and the lowest consumption rate.

Mainly used for wet or dry sandblasting and offers excellent coating preparation and adhesion properties.

6.5 - 7.5

Angular to Subangular

Media

Description

Used for

Hardness

Shape

Glass Beads

Glass Beads are manufactured into preformed ball shapes, which are very effective in leaving very smooth surfaces. It produces a super smooth and brighter finish compared to angular abrasives. Glass Beads can be recycled approximately up to 30 times.

Commonly used for automotive restoration, stainless steel fabrication, polishing of castings, and light deburring of metal molds and parts.

6-6

Round

Steel Shot

Steel Shot is manufactured into a spherical pellet-type abrasive made from carbon steel. It often produces a very smooth surface after use.

Steel shot abrasive is often used in cleaning and polishing metal surfaces and parts in automotive, aerospace, construction, foundry, shipbuilding, rail, and more.

40-51 HRC

Spherical

Corn Cob Grit

Corn Cob Grit is an organic, soft, and natural abrasive from hard cob. It is tumbling and absorbent that dries surfaces. Corn cob grit is non-toxic and safe for operators.

It is best used on wood surfaces and does not create any damage on the treated surface. It is used on oily and moist surfaces that quickly absorb it while finishing rough parts.

4-4.5

Ground, Angular shape

Walnut Shell Grit

It is a very versatile soft abrasive, organic, and biodegradable. Same as corn cob, it is non-toxic and imposes no hazard to health.

Best used in stripping and cleaning delicate surfaces and parts, Walnut Shell Grit provides effective applications such as cleaning hardwoods and aircraft and automotive stripping.

4.5-5

Angular

Garnet

Garnet is a natural silicate mineral deposit. It has a high stripping rate, very low dust and the lowest consumption rate.

Mainly used for wet or dry sandblasting and offers excellent coating preparation and adhesion properties.

6.5 - 7.5

Angular to Subangular