COATED ABRASIVE
Coated Abrasives are similar to grinding wheels but are two dimensional in structure as in sand paper which has a single layer of abrasive. The main component are shown as below. unlike a grinding wheel which has a three dimensional layer of abrasive. The operation of material removal with coated abrasives is called sanding instead of grinding with bonded abrasives.
The mechanics of material removal in sanding with coated abrasives is similar to bonded abrasives.

 

COMPONENTS OF COATED ABRASIVES
Coated abrasives products have mainly 3 components, a backing which is flexible, a bond which is strong and flexible, and a single layer of abrasive. The main components are shown below. 

The make coat is the first coat of adhesive which is applied on the backing and this is followed by the abrasive which is placed with a desired orientation on this make coat. After curing this coat in the space between the abrasives a size coat of adhesive is applied which helps the grain to get firmly anchored. Coated abrasives are made with grains which are longer and tougher than bonded abrasives. This ensures that the abrasive particles penetrate deeper with lesser forces and withstand very high pressures on the grain.

The main components are hence:
· Backing
· Grain
· Bond

Backing supports or provides the foundation for the abrasive grain and because it is flexible allows the abrasive grain to be applied in the job in a variety of ways.
The Adhesive holds the abrasive grain in place till it is used up in the proper position in the backing
The Abrasive grain forms the cutting edge to grind, remove or polish material. Each grain in turn has a number of cutting edges, which form basic wedges for material to be removed.

TYPES OF BACKINGS
· Paper
· Cloth - Cotton, Polyester and Rayon
· Vulcanized Fibre
· Combination - Paper and cloth laminated
· Wide mesh cloth - Screen Bak
· Polyester film

TYPES OF COATED ABRASIVE PRODUCTS:

FIBRE DISCS
Fibre discs also called Sander Discs are used in sanding and polishing on portable sander polishers.

                                                          

These products use Vulcanised fibres as backing materials and are used mounted against a backup pad made of rubber or Phenolic plastics. They can be used for very fast material removal rates without generating heat. They are made fully or partial coated with grain in round or Rossette shapes.
AVOS Discs are new discs made by Norton which enables operator using discs to see the job he is grinding. This ensures no over grinding.
These discs are made with specially shaped holes in octagonal shape.