Bonded Abrasives: What They Are and What They’re Used For
Bonded abrasives are made with either organic or vitrified binders and are generally used for cutting, grinding, sharpening, and polishing applications, although they also serve other purposes.
Abrasive Products with Vitrified Bond
Vitrified bonds are the most commonly used in precision grinding.
Products manufactured with these bonds feature a porous structure held together by glass or similar vitreous binders. Their strong cohesion is achieved by firing in kilns at temperatures ranging from 900 to 1250 °C.
The porosity and strength of products made with vitrified bonds offer high material removal rates, while their rigidity ensures excellent precision in grinding and sharpening processes.
Another key advantage of vitrified bonded abrasives is their resistance to water, acids, oils, and normal temperature fluctuations.
Abrasive Products with Organic Bond
Organic bonds are used in the manufacturing of grinding wheels and cutting and grinding discs—reinforced or non-reinforced—for fixed or portable machines where rapid material removal is required.
A variety of organic polymers are used as binders for these abrasive products, but thermosetting phenolic resin is the most common.
The resin is cured with heat in strictly controlled ovens at temperatures between 150 and 200 °C.
Abrasive products with organic bonds are tougher and less brittle than vitrified ones. Their inherent strength makes them particularly suitable for high-stress applications or high rotational speeds, often with added reinforcement from fabric or fiberglass.
Grit Size
Grit size refers to the approximate number of openings per linear inch in a sieve used to grade the abrasive grain. The higher the number, the smaller and finer the grain. Conversely, a lower number indicates coarser grains.
Coarse grains are used for rapid material removal when surface finish is not critical, while fine grains are used for achieving smooth, fine finishes.
Hardness Grade
The hardness grade measures the strength of the abrasive bond, which depends on the amount of binder in the product.
This grade does not refer to the hardness of the abrasive grain itself, but rather the tenacity of the bond in holding the grain. In theory, very hard abrasives should be paired with softer bond compositions to allow for high cutting efficiency with gradual wear. Conversely, softer abrasives should be used with harder bonds to enhance durability.
The grade is designated by letters of the alphabet, ranging from E (softest) to Z (hardest).
Types of Abrasive
It is the abrasive grain that performs the actual work—penetrating the workpiece and removing material.
The most critical characteristics of an abrasive grain are hardness, toughness, and sharp edges.
High-Performance Abrasives
High-performance abrasives are made from the following synthetic materials:
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Silicon Carbide
Extremely hard; ideal for working with titanium, glass, minerals, ceramics, porcelain, and stone. -
Aluminum Oxide (Corundum)
A universal grain for various industrial applications. Offers an ideal balance of strength and hardness. Perfect for intermediate sanding and finishing. -
Zirconia
A self-sharpening abrasive that provides high-performance grinding. Excellent for medium to high-pressure applications with high material removal rates. -
Ceramic Aluminum Oxide
A geometrically shaped grain offering maximum material removal and faster cutting. Produces lower surface temperatures and significantly extends product life.
Choosing the Right Abrasive Product
When selecting the most suitable abrasive product for a given application, consider the following factors:
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The material to be ground – its type and hardness
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The amount of material to be removed
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The geometry of the workpiece and the required surface finish
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Type of machine – fixed or portable – available power and working conditions
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Machine speed and feed system
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Grinding contact area
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Grinding fluid – whether the application is wet or dry
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Grinding operation conditions and tolerances
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For precision grinding wheels, the method used for dressing the wheel
To truly understand the difference between the ordinary and the exceptional, contact us for expert guidance in selecting bonded abrasives.