Beyond
Surface Treatment,
Surface Engineering.
Blasting Media: Shapes and Materials
The right choice of blasting media impacts the operating cost of the process, this is the "fuel" of a blaster and the booster of the savings. This small overview is about the shapes and materials used in blasting - peening machines today, it is not meant to be exhaustive, and each case must be assessed for a tailored answer.
The engineering law governing the process is simple: kinetic energy. Controlling the media's speed and choosing its mass carefully is the way to succeed.
Size chart reference: SAE J444.
Shapes are described first, materials follow..
What media shapes are used in blasting?
Shots vs Grit.
Shots - Spherycal - "S"
Shape is spherical, identified by an "S" followed by some numbers that identify shot's size.
Good results in soft cleaning and deburring.
Usually it is the best shape for shot peening.
Good performance in cleaning and peening processes.
Grits - Angular - "G"
Shape is angular, identified by a "G" followed by some numbers that identify size.
Really good performance in blasting to obtain a specific roughness and cleaning against hard materials like scale after heat treatments.
Blasting parameters must be carefully controlled to avoid damaging of the parts.
What are the blasting materials?
Here, the most common in the industry.
Steel
It's the most popular shot/grit material, available in a wide range of sizes.
Besides size, the material's hardness strongly impacts the finishing process.
The percentage of dust in the bag can vary widely between producers and affects the cost.
Waste is moderately flammable and can become explosive under certain conditions, must be handled with care.
Steel must be stored in a dry place to avoid spoilage; packaging is not an accessory but a shield to preserve the product, specially if purchased in big quantities for better price.
Stainless Steel
It is available in shot/grit shape and wide range of sizes.
Hardness plays a critical role and influences finishing.
Benefit is a limited chemical interaction with the parts, this may be critical for further operations like electrochemical finishing.
Stainless media are consistently expensive compared with regular steel, so are chosen considering their impact on process cost. A good and well tuned filtering system avoids wasting media that is still reusable.
Waste can be really flammable so handling it with care it is not an option.
Ceramic
Ceramic is a kind of spherical shots identified by a letter B followed by some numbers; the higher the number the smaller the shots.
Ceramic is hard yet very fragile, so this shots can provide good cleaning performances without spoiling the parts.
Consistency in shape and dimensions give high consistency during process, a benefit you pay for, since it isn't cheap.
To protect ceramic media during the process CM machine has a special kit to save media from being accidentally broken while flowing inside of the machine. It is always possible with a little spending to install this kit and convert an equipment made to run with steel to run with ceramic.
Ceramic waste is NOT reacting to fire, sparks, as metal dust usually is, so helps a lot to make the environment where it is performed safer compared with other kinds of media.
Beyond the few introduced here, there are countless others — different materials, chemistries and manufacturing methods — too many to list.
The Engineering Behind the Choice: Our Consultancy Approach
Choosing a blasting media based solely on price-per-pound is the most common hidden drain on manufacturing margins. At CMblasterUS, we analyze the process through three technical lenses to ensure your choice is a strategic asset, not just a consumable:
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Kinetic Customization: We balance turbine velocity with the Specific Gravity of the media. Whether you need high-momentum steel for deep descaling or low-density aluminum/ceramics for delicate, thin-walled geometries, we engineer the impact energy to protect your part's structural integrity.
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The Hardness Differential: We evaluate the hardness ratio between the media and your specific workpiece. Our goal is to find the "Economic Sweet Spot"—the exact point where you achieve the required surface morphology (Ra/Rz) without causing unnecessary wear on your machine’s internal components.
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Metallurgical & Chemical Integrity: We prevent "invisible" failures. By selecting chemically inert media, we eliminate risks like ferrous contamination on stainless steel or surface energy imbalances that can lead to catastrophic delamination in subsequent coating or bonding processes.
Don’t just buy a commodity. Optimize your process.
The right media choice is a calculation of Total Cost of Ownership (TCO), factoring in purchase price, cycle times, disposal costs, and machine maintenance.
Are you looking to reduce your cost-per-part or solve a complex surface challenge? Are you struggling to source a specific media?