Page 460 - NORTON cutting-off and grinding wheels - industrial

460 TECHNICAL INFORMATION
TECHNICALINFORMATION
ABRASIVES
BACKING
BONDS
SIZER COAT
MAKER COAT
COATED ABRASIVES
ABRASIVE TYPES
The ideal abrasive grain offers maximum resistance
to point wear, yet fractures before serious dulling
occurs, thereby satisfying both stock removal and
finishing requirements.
SYNTHETIC ABRASIVES
• Aluminium oxide is tough and well adapted to
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
• Silicon carbide is the hardest and sharpest of the
minerals used in coated abrasives. Its hardness
and sharpness make it the ideal abrasive for
sanding non-ferrous metals (aluminium, brass,
bronze, magnesium, titanium, etc.), rubber, glass,
plastics, fibrous woods, enamel and other relatively
soft materials. Silicon carbide is superior to any
other abrasive in its ability to penetrate and cut
faster under light pressure
• Zirconia alumina has a unique self-sharpening
characteristic which gives it long life on rugged
stock removal operations. Zirconia alumina is well
suited for heavy grinding of metals and planing
of wood, because the controlled fracturing of the
grain continuously produces sharp, new abrading
points
• 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 forged and carbon steels, high nickel
and cobalt alloys
NATURAL ABRASIVES
• Emery is a natural composite of corundum and
iron oxide. The particles are blocky in shape and
tend to cut slowly, thereby producing a polishing
action on the material being abraded. Used for
general maintenance and polishing of metals and
in very fine grits for highly technical polishing, such
as preparing metallurgical specimens requiring
very close tolerances. Emery products are black in
colour
ABRASIVE GRAIN DISTRIBUTION
There are two types of abrasive grain coverage on
the backing:
• Openly spaced distribution where between 30%
and 60% of the backing is covered leaving large
spaces between each abrasive grain. It is used
in operations where the grinding swarf would
otherwise ‘load’ or clog the surface, reducing
cutting efficiency and shortening the coated
abrasive life
• Closely packed grain distribution is where the
grain completely covers the backing. The greater
number of abrading points in a given area leads
to faster stock removal. It is recommended where
loading is not a problem and where smoother
surface finishes are desired
TECHNICAL INFORMATION
WHAT IS A COATED ABRASIVE?
Modern coated abrasives are the product of an extremely technical process developed through many
years of research and development. They remain, however, a product composed of three basic elements:
a flexible or semi-rigid backing to which abrasive grains are bonded by an adhesive.