Bonded Abrasives Vs Coated Abrasives

There are two major types of abrasive tools used for surface finishing and material removal. They vary greatly in terms of uses, performance, qualities and their constructions. In this article, we will cover all the details regarding bonded and coated abrasives, their differences and how to choose between them.

WHAT IS BONDED ABRASIVES?

Abrasive grains bound together by a bonding agent make up bonded abrasives. This mixture is molded into shapes like wheels, stones, segments, or mounted points, then solidified. Common types include vitrified clay, resin, rubber, and metal. Key features of bonded abrasives are:

• Abrasive grains: these are the cutting particles that can be natural or organic, including emery or corundum, or they can be synthetic or created like aluminum oxide, silicon carbide, diamond, etc. 
• Bonding Agent: The bonding agent is crucial for an abrasive tool's strength and durability, as it's the material that holds the abrasive grains together. Common types include vitrified, resinoid, rubber, metal, and silicate bonds.

APPLICATIONS OF BONDED ABRASIVES

Bonded abrasives are a highly versatile tool and can be used for a wide range of applications, including removal of heavy stock, fine finishing, blending, polishing, and deburring of in various sectors, including metal fabrication, tool and die making, automotive and aerospace. The particular bonded abrasive type (material, grit size, bond type, and form) is chosen with care, taking into account the equipment being used, the material being treated, and the intended result.

WHAT IS COATED ABRASIVES?

Coated abrasives are made up of abrasive grains glued to a flexible backing material which can be paper, cloth, fiber, film, plastic, or a mix of these. Adhesives or bonds, sometimes in several layers, are used to stick the grains to the backing. The abrasive grains are available in various sizes (grits) and materials. The following are the key features of coated abrasives:

• Backing Material: This gives the abrasive its flexibility and structural stability. Common types of backing materials are paper, cloth, film, fiber plastic, and much more. 
• Adhesive (Bond): The adhesive (bond) in sandpaper has two main layers: the maker coat, which initially binds the abrasive grains to the backing, and the sizer coat, which adds rigidity and durability. Some specialized sandpaper also includes a top coat for properties like heat resistance or anti-clogging.