Page 489 - NORTON cutting-off and grinding wheels - industrial

TECHNICALINFORMATION
489
TECHNICAL INFORMATION
MOUNTING
A wheel should only be mounted onto the machine
for which it was intended. The speed of the spindle
on which the wheel is mounted should not under
any circumstances exceed the maximum RPM
speed specified for the wheel when it is full size.
The wheel should fit freely, but not loosely, onto
the spindle or spigot diameter of the flange plates.
Wheels, blotting paper washers and flanges should
be free from foreign matter. Certain wheels have
a positioning mark (Mount Down or Mount Up)
marked on them. Care must be taken to ensure
that this mark occupies the position stated by the
manufacturer.
REDUCING BUSHES
Where a removable bush is used as a means of
reducing the bore of an abrasive wheel, care must
be taken to ensure the bushes should not project
beyond the side of the wheel and the wheel blotter.
The clamping faces of the flange plates MUST
clamp on the mounting washers attached to the
wheel and not on any part of the reducing bush.
Reducing bushes should never be used on wheels
less than 6mm thick or on products with a back or
web of less than 6mm. Never use plastic bushes on
wheels used with portable grinding equipment.
MOUNTING WASHERS
Blotters should be used with all grinding wheels
unless there is a specific exemption. Blotters should
be slightly larger in diameter than the mounting
flanges and free from any scuffs, wrinkles or other
damage.
MOUNTING FLANGES
Mounting flanges are designed to clamp the wheel
to the machine and transfer the driving forces from
the machine spindle to the grinding wheel. They
should be designed to take the driving forces away
from the area around the grinding wheel bore and
generally should be not less than one third of the
grinding wheel diameter.
Flange surfaces should be flat, free from burrs,
bumps, bruises and other damage. Flanges should
be of equal diameter, have equal bearing surfaces
and be properly recessed or undercut.
The rear flange must be positively driven by the
machine spindle, being either keyed or shrunk onto
the spindle.
Flanges must run true to the machine spindle.
Clamping nuts (centre nut locking) should only be
tightened sufficiently to hold the wheel securely
without slippage and must not be over-tightened.
When flanges are clamped by a series of screws,
they should be tightened in stages uniformly in a
diametric sequence.
In most instances it is appropriate to tighten the nut
or screws by hand with the correct tool (spanner
or hexagonal socket key) until they stop turning.
By adopting this technique it is very rare that the
wheel would be under-tightened and impossible to
over-tighten the wheel. Bolts for mounting wheels
with inserted nuts should be long enough to engage
an adequate length of thread, i.e. equal to the thread
diameter, but must not protrude through the nut
insert.
For recommended designs of flanges, refer to the
FEPA Safety Guidelines.
CAUTION
After mounting or re-mounting a grinding wheel
on a machine, stand well clear, ensuring that there
are no persons in line with the wheel and allow the
wheel to run free for two minutes. A re-mounted
wheel should always be treated as if it were a new
wheel.
TYPE 06 CUP WHEELS ½ FIXED MACHINES
The diameter of the flange and paper washer inside
the cup must be smaller than the diameter of the
cup recess to avoid any risk of radial pressure
on the wheel. When used for work heavier than
light tool and cutter grinding, the back flange may
be larger than that inside the cup but the recess
diameter of both flanges must be equal.
MOUNTED POINTS & WHEELS
The spindle dimensions of the mounted point must
be suitable for the collet being used, and the spindle
overhang corresponding to the machine speed
should be observed.
TYPE 31 GRINDING SEGMENTS
Segments are held by special chucks with suitable
provision for adjustment to compensate for segment
wear. To prevent breakages segments should not
protrude more than 1,5 times their thickness from
the clamping chuck face, and should be mounted
with markings uppermost.