Bonded Abrasives: A Brief Selection Guide

How do you differentiate one class of abrasive grain from another? Premium abrasives are often distinguished as either natural or synthetic, and both categories can be further sub-divided into distinct materials. Material classification is ideal for the raw or powder form. But end-users looking for an abrasive finishing solution are often seeking a solid-state product where abrasive grains are confined in a binder. These are typically defined as either coated or bonded abrasives.

Coated Vs. Bonded Abrasives: What’s the Difference?

Both coated and bonded abrasives describe a cutting, grinding, or finishing product composed of extremely hard-wearing particles compacted into a solid form. Coated abrasives are engineered by depositing one or more layers of abrasive on a flexible substrate like a sheet or a belt (i.e. sandpaper). Bonded abrasives are made by combining premium grains with functional filler materials and bonding agents. This mixture is compressed into a final shape such as a grinding wheel, a grinding disc, or  sharpening stone..

Choosing Bonded Abrasive Grains

Bonded abrasives are the product of choice for industrial grinding and finishing of hard materials like metal and ceramic alloys. The nature of your workpiece is the first thing to consider when selecting an abrasive system. Standard material finishing requirements may be satisfied by commodity alumina (Al₂O₃), but the surface quality finish often leaves much to be desired. This is usually symptomatic of poor bulk particle properties such asbroad particle size distributions (PSDs) and/or coarse grit sizes. It may also come down to chemistry, microstructure, or various other phenomena.

A finer surface finish for hard substrates requires a bonded abrasive solution made with precision engineered grains. Alumina remains the recommended material for such applications, but a high-purity monocrystalline alternative is preferred to commodity, lower quality materials (i.e. brown-fused alumina). Compounds of alumina—zirconia also sit comfortably alongside high-purity monocrystalline alumina in terms of aggressive material removal rates with good surface uniformity, though alumina zirconia is only compatible with resin bond systems.

Selecting the right bonded abrasives subsequently comes down to an array of business and material considerations. Here we will outline a few recommended materials by application, to give you more insight into the selection criteria for bonded abrasive grains.

Bonded Abrasives by Application

• Foundry: Durability is critical in the harsh environs of metal foundries. Abrasive grains like ZF Alundum®, composed of high-density alumina-zirconia with an ultra-blocky profile, are ideal for foundry grinding wheels.
• Heavy industry: Applications requiring heavy stock removal on stainless and high alloy steels benefit from the added anti-friability of alumina-zirconia. Norzon NV or ZS Alumina Zirconia grains are especially well-suited for conditioning and finishing in heavy industry due to their high cutting action at lower applied pressures.
• Thin wheels: The right bonded abrasive for thin wheels is primarily determined by application. For grinding and notching, no grain can match Saint-Gobain’s Cerpass XTL® seeded gel abrasives for material removal rates nor long-lasting performance. 
• Track grinding: Rail surfacing is a cost-critical process that benefits from rapid cutting actions to accelerate returns to operation. Norzon NV® grains offer spectacular performance in track grinding applications.
• Precision vitrified: Precision vitrified grains are specially engineered for maximum material removal rates without sacrificing a high-quality surface finish. Cerapss HTB is the market-leading solution for this application owing to its unique microstructure and unmatched sharpness.

Looking for Bonded Abrasives?

Saint-Gobain Abrasive Grains is the industry-leading developer of precision engineered grains for bonded abrasive applications. Interested in making the transition from commodity products to truly high performance solutions? Contact a member of the Saint-Gobain team today.