Mastering The Craft: A Comprehensive Guide To Using Bonded Abrasives

How can you distinguish between different abrasive grain classes? High-quality abrasives can be classified as natural or synthetic, and both can be further separated into other materials. The material classification works best in powder or raw form. However, end customers seeking an abrasive finishing solution frequently seek solid-state products with abrasive grains in a binder. Usually, these are described as coated or bonded abrasives.

A BONDED ABRASIVE: WHAT IS IT?

A grinding or cutting tool known as a bonded abrasive is made of abrasive grains firmly bound together by a bonding agent and usually reinforced with a woven material. Grinding and cutting wheels, as well as "stones" of various sizes and shapes, fall within the category of bonded abrasives.

WHAT'S THE DIFFERENCE BETWEEN BONDED AND COATED ABRASIVES?

Coated and bonded abrasives are cutting, grinding, or finishing products made of incredibly durable particles compressed into a solid state. Creating coated abrasives involves applying one or more abrasive layers to a flexible substrate, such as sandpaper, sheet, or belt. Meanwhile, premium grains are combined with bonding agents and functional filler components to create bonded abrasives. This mixture is squeezed to produce the desired shape, a sharpening stone, grinding wheel, or grinding disc.

THE PRINCIPAL ELEMENTS OF BONDED ABRASIVES

1.     ABRASIVE GRAINS

Grit, often known as abrasive grains, comprises particles of artificial materials. The physical characteristics of each grain, including its form, sharpness, hardness, and friability (the tendency to break down), are determined by its chemical structure. When creating bonded abrasives, common grain types include:

• A - ALUMINIUM OXIDE - This complex, blocky grain is utilized to cut metals and other materials with high tensile strength without breaking too much.
• C - SILICON CARBIDE - An extremely sharp and strong abrasive that works well on non-metallic materials like concrete.
• Z – ZIRCONIUM - A thick, wonderful crystalline grain that can be utilized to remove rough stock.
• SG – CERAMIC - A particular type of aluminum oxide that is three or twice as durable as regular aluminum oxide

2.     BONDING AGENT

The glue that binds the grains together determines the wheel's resistance.

3.     REINFORCEMENT

The reinforcement material offers strength to handle lateral pressure applied during use and to run the abrasive product at the indicated maximum RPMs. The product's structural strength is determined by this crucial component, which is invisible to the unaided eye.

INTEGRATING THE ELEMENTS

These three elements are mixed throughout manufacturing to create an abrasive tool. An automated hydraulic press measures, mixes and presses the grains and bonding ingredients.

SELECTION OF BONDED ABRASIVE GRAINS

Bonded abrasives are preferred for industrial grinding and finishing hard materials such as metal and ceramic alloys. When choosing an abrasive system, the first thing to consider is the type of workpiece you have. Commodity alumina (Al2O3) may meet standard material finishing criteria. However, the surface quality finish frequently needs to catch up to expectations. Poor bulk particle characteristics, such as broad particle size distributions (PSDs) and coarse grit sizes, typically cause this. It might also be related to microstructure, chemistry, or other phenomena. 

A bonded abrasive solution with precisely tailored granules is needed for a finer surface quality for rigid substrates. For these kinds of applications, alumina is still advised, although high-purity monocrystalline alternatives are favored over lower-quality commodity materials (such as brown-fused alumina). Although alumina-zirconia is only compatible with resin bond systems, compounds of alumina-zirconia likewise compare favorably regarding aggressive material removal rates with good surface uniformity with high-purity monocrystalline alumina.

Therefore, choosing the finest bonded abrasives requires careful evaluation of several material and commercial factors. To help you better understand the requirements for choosing bonded abrasive grains, we will provide some suggested materials here, broken down by application.

BONDED ABRASIVES APPLICATION

• FOUNDRY: In the rigorous conditions of metal foundries, durability is essential. For foundry grinding wheels, abrasive grains such as ZF Alundum® are perfect. It is made of high-density alumina-zirconia with an ultra-blocky profile.
• HEAVY INDUSTRY: Applications requiring high alloy and stainless steels with substantial stock removal can profit from the additional anti-friability of alumina-zirconia. Because ZS Alumina Zirconia grains have a high cutting action at lower applied pressures, they are particularly well-suited to conditioning and finishing in heavy industry.
• THIN WHEELS: Application is the primary factor in selecting the appropriate bonded abrasive for thin wheels. No grain can equal seeded gel abrasives for material removal rates or long-term performance in grinding and notching.
• TRACK GRINDING: Rapid cutting activities help hasten returns to service for rail surfacing, a crucial technique to cost. 
• PRECISION VITRIFIED: The grain composition of precision vitrified products is carefully designed to achieve optimal material removal rates while maintaining a superior surface finish.