At Fandeli recognize that an informed and educated abrasives user can better select and use our coated abrasive products. Therefore to help manufacturing users, we offer these background materials and technical tips.
The selection of the proper abrasive mineral is important to the productivity of coated abrasive applications. Although natural minerals were important historically, the demands for quality and productivity in manufacturing have required the extensive use of synthetic minerals that offer consistent coated abrasive characteristics. Each type abrasive grain has unique properties and selecting the best grains requires close attention to the type of work material being ground, the cost of the abrasive minerals and its performance under actual working conditions.
The ability of the abrasive grain to penetrate the article being abraded depends to a large extent upon the hardness, toughness and shape of the abrasive. The types of abrasives used in order of hardness are Silicon Carbide, Alumina Zirconia, Premium Aluminum Oxide, White Aluminum Oxide, Brown Aluminum Oxide and Emery.
SILICON CARBIDE This mineral is synthetically produced in electric furnaces to produce a glossy black color and a high degree of hardness. Due to its brittle characteristics it fractures into sharp sliver-like wedges having cutting edges that permit rapid stock removal. Recommended for finishing nonferrous metals such as brass, bronze, copper and aluminum; and other materials such as leather, glass, wood, rubber and plastic. It is also used to finish and polish automotive primers, lacquers and sealers in general.
ALUMINA ZIRCONIA This mineral is a mixture of Zirconium Oxide dissolved in Aluminum Oxide at molten temperatures. Coated abrasives use a micro-crystalline structure form of this mineral that is characterized as sharp, hard and extremely tough. Because of the structure and extreme toughness, smaller particles of grain break off in use and at a much slower rate than standard aluminum oxide. It produces superior performance on a wide variety of materials of both high and low tensile strength under high grinding pressures. Typical applications include grinding of carbon steel, stainless steel, tough bronzes, a wide variety of stainless steel and exotic alloys, grey malleable, ductile and nodular cast iron, aluminum, titanium, etc. Alumina Zirconia is excellent on high grinding pressure applications and very often it is equally effective at lower grinding pressure levels also.
PREMIUM ALUMINUM OXIDE This is a synthetic mineral that begins as fused Aluminum Oxide of high purity and is treated at very high temperatures to improve its hardness and friability properties. With these improvements, the grains maintain a sharp cutting edge that cuts cooler, resulting in longer life and lower grinding costs. It is used for grinding high tensile strength materials such as steel, stainless steel and tough bronzes. It is also very effective for rough grinding of many low tensile strength materials such as grey iron, low carbon steel, aluminum, and brasses when heavier grinding pressures are used resulting in longer life and lower grinding costs.
WHITE ALUMINUM OXIDE White Aluminum Oxide is a durable manufactured abrasive which is characterized by long life of its cutting edges. It is recommended for sanding of all types of wood.
BROWN ALUMINUM OXIDE This mineral has a grain with a large crystal size in its structure. It is characterized as sharp, hard, and tough. It is used for grinding and polishing high tensile strength materials such as steel, stainless steel, tough bronzes, etc. It is also very effective for rough grinding of many low tensile strength materials such as grey cast iron, aluminum, brass, etc. when heavier grinding pressures are used.
EMERY Man-made emery is a regular aluminum oxide containing a small amount of ferric oxide. This addition gives high durability. Emery is recommended for hand polishing of ferrous and nonferrous materials.
Cloth, resin fiber, paper, and a combination of these materials are the most popular backings used in the manufacturing of coated abrasives.
CLOTH includes "J", "X", and "Y" weights. "J" weight (jeans) cloth is used for polishing and finishing operations or where flexible products are required. "X" weight (drills) is a heavier, stronger and less flexible material that is used in heavy and medium duty operations. "Y" weight (sateen) is an extra heavy backing for heavy duty grinding.
RESIN FIBER backings consist of multiple bonded layers of impregnated paper. They are tough and strong for disc uses.
PAPER is used in "A", "C", "D", "E", and "F" weights. "A" weight is light and flexible. "C" and "D" weights are stronger and less flexible. "E" and "F" weights are still stronger mostly for rolls, belts, and discs where high resistance to tearing is required.
COMBINATION backing is a result of laminating "E" weight paper and light cloth. This is primarily for disc and drum sanding.
The primary forms of coated abrasives are: Sheets, Discs, Rolls, Belts, PSA (Pressure sensitive adhesives) discs, flap wheels, bodyfiles, specialties and non-woven.
Paper and cloth discs
Quick change discs
Flap wheels -- 4" to 8"
Body file sheets
Identifying the size of the grit to be used is very important, especially considering the large variety of grades available.
The following table compares the ANSI (American National Standards Institute) norm B74.18-1984, FEPA "P" (European Federation of Abrasives Producers) and JIS (Japanese International Standard) regulation. These three standards are compared with the average size of the particles in microns and with a simplified grading pattern (that meet two or more grits in one value).
This chart shows the five basic types of operations with its corresponding grade: Grading Systems Table