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COATED
ABRASIVES
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ABRASIVE GRAIN SIZE
Abrasive grains are separated (graded) into standard particle sizes using screens carefully made from silk threads
of exact size and number per square inch to ensure extreme accuracy.
The grit number (mesh number) appearing on the coated abrasive backing represents the number of openings
per linear inch in the final screen. The European standard of grit sizes is the FEPA grading system. All FEPA grit
sizes are preceded with the letter ‘P’, i.e. P180 etc. However, some products are coated with non-FEPA graded
abrasives like Emery, Glasspaper, Flint and Ceramic.
Further information about the different abrasive grading systems is given in the table on the opposite page.
ABRASIVE BONDS
There are two common types of adhesives in use: one based on animal glue and the other based on synthetic
heat hardenable resins. The adhesive is applied with a minimum of two bonding applications. The first, or ‘maker’
coat, adheres the abrasive grain to the backing ensuring proper anchoring and orientation. After drying or curing,
the second or ‘sizer’ coat is applied. The ‘sizer’ adhesive unites with the ‘maker’ bond to provide final grain
anchoring and the required total adhesive level for the finished product.
BACKING TYPES
BACKINGS
Whether paper, cloth, vulcanised fibre or polyester, the backing must be smooth enough for a uniform adhesive
coating, strong enough to withstand grinding pressures and flexible enough to conform to contours.
PAPER
The lighter the backing, the greater the degree of flexibility; the heavier the backing, the greater the resistance
to tearing.
A-Weight (85g)
– Light and flexible, A-weight is used primarily for hand finishing operations both wet and dry.
Grits 80 and finer.
C-Weight (115-125g)
– Stronger and less flexible than A-weight. This backing is chosen for hand sanding,
dry or wet, and for use on small portable power sanders. Intermediate through fine sanding. Grits 60 through 180.
D-Weight (150-185g)
– Stronger and less flexible than C-weight. This backing is also chosen
for hand sanding and for use on small portable power sanders. Coarse through intermediate sanding.
Grits 36 through 80.
E-Weight (220-270g)
– Stronger and less flexible than D-weight, this backing is used primarilyon roll,
belt and disc applications where high resistance to tearing is needed.
F-Weight (270-300g)
– The strongest, least flexible paper backing utilised. Used for crankshaft lapping rolls,
tannery industry belts and rolls.
CLOTH
Cloth backings are more durable than paper, offering greater resistance to tearing, and can tolerate continual
bending and flexing during use.
The cloth backing has construction characteristics designed to make it ideally suited to specific applications.
Below is an explanation of the weights of cloth backing available in the Flexovit Range.
J-Weight
– The lightest and most flexible cloth backing, this backing is used where surface finish and uniformity
are more important than stock removal. It is ideal for finishing, blending and where flexibility is required,
such as when working on curved surfaces.
X-Weight
– This backing is strong and relatively stiff when compared to J-weight. Consistent productivity,
excellent finish and long product life are characteristics of products made using X-weight backings. Products
with a coarse grit and an X-weight backing are ideal for stock removal applications and the finer grits are more
suited to finishing and polishing applications.
TECHNICAL INFORMATION