With very few exceptions, most coated abrasive applications require some form of support. The most popular form of backup for belt operations is the contact wheel. Contact wheels come in a variety of sizes, shapes, compositions and configurations. Most contact wheels or contact rolls are made of either metal, rubber, or cloth. Steel and Aluminum have limited application except for holding shape and tight tolerances and is rarely used because metal contact wheels accentuate grinding problems and poor machine conditions.
Rubber is the most widely used of the contact roll materials.
Rubber can be made either hard or soft. Generally, the harder the contact wheel, the more aggressive the cuffing action will become, but the finish will deteriorate. The hardness is determined by the number and size of plys per inch of wheel thickness and how they are stitched together. Cloth wheels are not as aggressive as rubber wheels and are generally used in polishing operations where stock removal is not the key issue. Smooth Wheels have no grooves cut into the face.