Abrasive grain types
Aluminium oxide. This abrasive is commonly used in most applications involving discs used on angle grinders. It is tough, blocky abrasive and is wear resistant, although loss of sharpness may be critical when working on hard metals and stainless steel. More friable white abrasive is used in conjunction with thin (less than 2mm width) discs for reducing cutting times. Often competitively priced compared to other abrasives. Versatile can be used for grinding and sanding of most metals and wood. Often designated by the letter A or WA in the specification of the disc.
Zirconia aluminium oxide. It has a unique self-sharpening characteristic which gives it long life on rugged stock removal operations. Ideal for use on most metals and wood its long-lasting cutting characteristics and controlled fracturing of the grain make it especially suitable for use in flap discs on stainless steel. Often designated by the letter Z or ZA in the specification of the disc.
Silicon carbide. Harder yet more friable than conventional aluminium oxide is ideal for sanding glass, non-ferrous metals (aluminium, brass, bronze, magnesium and titanium), rubber, plastics, fibrous woods, leather, enamel and many stone based materials. Silicon carbide is superior to any other abrasive in its ability to penetrate and cut faster under light pressure. Often designated by the letter C or GC in the specification of the disc.
Ceramic aluminium oxide. 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. Ceramic abrasive can be used on most metals and woods.
Diamond. The abrasive is the hardest of all abrasives and is ideally suited for cutting and grinding of many stone based materials. Special diamond cutting discs are also available for use on reinforced concrete. However diamond abrasive should not be used for cutting or grinding of ferrous metals as it causes extreme abrasive wear.
Resinoid bond. Type 27, 41 and 42 discs are usually resin bonded with a fabric reinforcement. Resinoid bonded discs are based on thermosetting phenolic resin. 'Fillers' may be added to improve the mechanical strength or to act as grinding aids on dry grinding operations. Resinoid bonds are cured by heating in ovens under carefully controlled conditions at selected temperatures between 150C and 200C.
Resinoid discs are tougher and less rigid than vitrified wheels. Their inherent toughness makes them ideally suited to heavy duty operations at high operating speeds. (80 M/S).
Vitrified bond. Vitrified wheels have a high modulus of elasticity therefore highly rigid and brittle. This bond is not suitable for use with angle grinders except under carefully controlled conditions.
Adhesive bonded discs and wheels. Referred to as a coated abrasive, adhesive bonded discs and wheels have a backing that may be composed of paper, cloth or vulcanised fibre depending on the severity of the application. Paper backed discs are generally not used with angle grinders due to the high grinding forces imposed during grinding or sanding.
Electroplated bonded discs and wheels. A single coat of diamond particles is plated on to a steel form where it is held in a layer of nickel. The particles stand well proud of the surface and electroplated wheels provide free machining on materials such as GRP, fibreglass, carbon fibre and ceramics.
Abrasive grain size.
The grain or grit size is most important in determining a disc or wheel's ability to achieve the required surface finish and remove stock. The size is designated by a number which increases as grain size decreases. For example 10 grit has a median size of about 2.00 mm and 60 grit 0.25mm.
Standard sizes are used in all Abtec discs as specified in the European Standards laid down by FEPA. Coated abrasive size is preceded by the letter 'P'.
Typical grain sizes of discs used on angle grinders.
Coarse< 16, 20, 24, 30, 36, 40, 46, 50, 60, 80, 100, 120, 150 > Fine