54 / COATED ABRASIVES www.youtube.com/FlexovitEMEA THE TYPES OF GRAIN MOST COMMONLY USED ARE: COATED ABRASIVES INTRODUCTION Flexovit has a range of belts, discs, rolls, sheets and flap wheels for applications including heavy stock removal, dimensioning, grinding, deburring, cleaning, blending and finishing operations. WHAT IS A COATED ABRASIVE? When abrasive grain is strongly fixed to a flexible backing using adhesive, this is known as a ‘coated’ abrasive. The adhesive is applied with a minimum of two applications. The first, or ‘maker’ coat adheres the abrasive grain to the backing ensuring correct orientation. After curing, the second ‘size’ coat is applied. The sizer adhesive, united with the maker bond, provides final grain anchoring and the proper total adhesive level for the finished product. Some products have an ‘active grinding’ layer, a third coating that enables cooler cutting to minimize burn marks on the workpiece and reduce the need for rework. A stearate layer is also applied to some products to provide resistance to loading. This is known as ‘No-Fil® treatment’. ABRASIVE TYPES The ideal abrasive grain offers maximum resistance to wear, yet fractures before serious dulling occurs, satisfying both stock removal and finishing requirements. BACKING TYPES Whether paper, cloth, vulcanised fibre, a cotton or polyester film, the backing must be smooth enough for uniform adhesive coating, strong enough to withstand grinding pressures and flexible enough to conform to contours (if necessary). Aluminium oxide: tough grain for grinding high tensile materials, such as carbon steel, alloy steels, tough bronze and hard woods. Wherever toughness (ability to resist fracturing) is the main consideration, aluminium oxide out performs all other coated abrasive grains. A great solution for users looking for an affordable abrasive product. Zirconia alumina, unique selfsharpening grain for long life on demanding stock removal and heavy grinding operations. Ideal for planning wood, due to the controlled fracturing of the grain, which continuously produces sharp abrasive points. Has an excellent price vs. performance ratio. Ceramic aluminium oxide is a long-lasting, tough, dense abrasive due to its micro structure. The extremely small micron size particles break off during grinding, producing multiple new cutting edges. As it stays sharp, especially when used in medium and high pressure operations, it cuts at a higher rate than other abrasives. Recommended for use on harder materials such as forged and carbon steels, high nickel and cobalt alloys. The best solution for professional users sensible to high performance products and lower overall production cost. Backing Active grinding layer Abrasive grit Size coat Maker coat COATED ABRASIVES
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