COATED AND NON-WOVEN ABRASIVES Coated Abrasive Basics
Backing Types Backings are the base for the abrasive minerals and, combined with the adhesive bond, support and anchor the abrasive mineral. The backings used in the manufacture of coated abrasives are: Paper Due to the fine surface of paper, a consistent finish is produced. Paper weights include A, B, C, D, E and F weights with A being the lightest and most flexible and F being the heaviest and least flexible. A, B, C and D weight papers are used for hand sanding and light mechanical operations in the form of sheets, PSA (pressure sensitive adhesive) and hook and loop discs and sheet rolls. E and F weight papers are primarily used for more aggressive mechanical operations in the form of belts and discs. Cloth Cloth backings used for coated abrasives are identified by weight. Cloth backings are filled or “finished” with a variety of materials (glues or resins) to create various backing characteristics, most notably flexibility. Several cloth types are used: cotton, polyester, polyester/nylon and polyester/cotton blends, and rayon. There are three basic weights of cloth: J-weight or “jeans” is the lightest and most flexible. X-weight or “drills” is a heavier cloth that ranges in flexibility, strength and durability and is used on the broadest range of applications. Y-weight is a heavyweight drills cloth used on heavy-duty, high stock removal operations. Fiber Vulcanized fiber (cotton fibers which are chemically treated and then pressed under temperature and pressure to form a very durable backing) is used exclusively as the backing for resin fiber discs. Film Polyester film backing comes in 3 mil. and 5 mil. thicknesses, which have high strength and surface smoothness. They are used primarily in disc and roll applications requiring consistent surface finish, including powertrain applications. Foam Primarily used as backing for sponges, finer grit finishing discs, and buffing and polishing pads for cleaning and moist finishing applications. Mesh Mesh matrix backing comprised of thousands of tiny holes allowing for maximum dust extraction.
Coating Types There are two types of abrasive coatings used in the manufacturing of coated abrasives: open coat and closed coat. Glue, urea resin , and phenolic resin are the three basic bonding agents most commonly used. There are many size coat and make coat combinations, such as glue over glu e, urea over glue , and resin over resin . Glue over glue is the most flexible bond while resin over resin bond is moisture-resistant, harder, less flexible, heat-resistant and has superior grain retention. Bond Types An adhesive bond system is required to secure the abrasive mineral to the backing. All coated abrasive products are made with a two stage bonding process, the make coat and the size coat. The make coat is the first layer of bond applied to the backing. The make coat provides the adhesive base between the abrasive mineral and the backing. The size coat is the second coat , which is applied over the abrasive mineral and make coat to anchor the abrasive mineral and provide the desired physical strength of the finished product.
Open Coat With an open coat, 50% to 75% of the surface is covered by abrasive grain. There are evenly spaced voids between the particles of grain, helping reduce the effect of loading caused by wood dust or metal particles.
Closed Coat With a closed coat, the entire surface is covered with abrasive grain, with no voids between the particles. This is the most typical coating, permitting the greatest degree of stock removal and longest product life.
OPEN COAT (1/3 LESS GRAIN THAN CLOSED)
CLOSED COAT
Super Size Coating The Super Size coat is an optional final coat and grinding aid applied over the size coat to help maintain low grinding temperatures and prevent loading.
How to Read a Coated Abrasive Specification The Norton coated abrasive marking system includes both a generic and a technical marking, which identifies the actual components which make up the product. The markings identify the tradename, abrasive type, bond, backing, and any special features. An example would be: Norton Blaze R980P.
R 9 8 O P
Backing / Bond
Principal Abrasive
Coating
Random
Modifier
A = Lightweight Paper (A-D wts.) excluding Waterproof F = Fiber H = Heavy Paper / Resin Bond (E and F wts.) K = Cloth / Glue Bond (J and X wts.) M = Mesh PB = B-wt. Paper with Resin Bond and Latex Q = Various (e.g. Screen-Bak, Film, and Foam) R = Cloth / Resin Bond (H, J, X and Y wts.)
1 = Aluminum Oxide 2 = Aluminum Oxide 3 = Layered Aluminum Oxide 4 = Silicon Carbide 5 = Garnet
Odd = Open Coat Even = Close Coat
Designates different products within the same product group.
Additional description, often indicative of a product upgrade, i.e. "P" = Plus
6 = Crocus & Emery 7 = Aluminum Oxide 8 = Zirconia Alumina 9 = Ceramic Alumina
T = Waterproof Paper (A, C wts.) U = Lightweight Waterproof Paper/
NORaX Engineered Abrasive Resin Bond
EZ Essentials Stock Abrasives Program
www.nortonabrasives.com
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