Page 492 - NORTON cutting-off and grinding wheels - industrial

492 TECHNICAL INFORMATION
TECHNICALINFORMATION
SAFETY ADVICE
SAFETY IN THE STORAGE & USE OF GRINDING WHEELS
Stringent safety standards are maintained throughout the manufacture of Norton Grinding Wheels.
To reduce the risk of accidents further, the law requires that certain basic precautions are taken
in the storage and use of abrasive wheels.
RECEIPT
On receipt, grinding wheels should be thoroughly
examined to see if they show any signs of damage,
such as chips, cracks or discolouration. Damaged
wheels must not be used.
HANDLING
Any mishandling that results in the wheel being
subjected to any shock loading can damage all
grinding wheels. This can occur if the wheel is
inadvertently dropped, knocked over or banged
against any other object. This is equally true if
the wheel is secured on a pallet, which has been
dropped heavily from a forklift truck.
Any grinding wheel subjected to such mishandling
should be carefully examined for signs of damage.
If in any doubt – do not use.
STORAGE
Small wheels up to 80mm diameter, together with
cones, plugs, mounted points and wheels may be
stored in suitable bins, drawers or boxes. Type 02
cylinder wheels, type 06 straight cup wheels, type
12 dish wheels and type 13 saucer wheels should
normally be stacked on flat sides with cushioning
material between them. Thick rim and hard grade
cylinder and straight cup wheels may be stored
on their periphery as for plain wheels. Soft grade,
straight cup wheels, and all type 11 taper cup
wheels, should be stored base to base and rim to
rim, to prevent chipping of edges and cracking of
walls. Thin plain wheels, such as cutting-off wheels
or saw sharpening wheels should be stacked on a
flat surface of steel, or similar rigid material. Other
plain or shaped wheels of appreciable thickness,
are best supported on their periphery in racks. The
racks should provide cushioned, two point, cradle
support to prevent the wheels from rolling.
STORAGE CONDITIONS
During storage, grinding wheels must not be
subjected to:
• Exposure to humidity, water or other liquids
• Freezing temperatures
• Any temperature low enough to cause the
formation of condensation on the wheels
when moving from storage to an area of high
temperature
SHELF LIFE OF RESINOID
& VITRIFIED BONDED WHEELS
The outer surfaces of certain organically bonded
wheels may be affected by oxidation if they are
stored for long periods. These types of wheel should
not be stored for more than three years and proper
stock control should ensure that older wheels are
used first. In use, a three year old Resinoid product
will act considerably softer than a brand new wheel
(wheel will wear away more quickly).
The glass bonding system used in vitrified wheels
is very inert and generally only attacked by certain
acids. Cold temperatures can result in a vitrified
wheel cracking if wheels are put away wet and are
subjected to freezing temperatures. It must be
remembered that the longer a product is in storage
the chances of it becoming damaged increases.
Provided vitrified wheels are stored correctly,
thoroughly examined and mounted correctly they
will last for many years.
RING TEST
The ring test depends upon the damping
characteristics of a cracked wheel to alter the
sound emitted when it is lightly tapped. The test
is applicable only to vitrified bonded wheels.
To perform the ring test; support the wheel gently
with a finger through the bore section. Using a light
non-metallic implement (a file handle is ideal),
gently tap the wheel about 45° each side of the
vertical centre line. Rotate the wheel 45° and
repeat the test.
The sound and undamaged wheel will omit a clear
tone. If cracked, there will be a dead dull sound
– not a clear ring – and the wheel should NOT be
used. The ring test should be carried out in a place
where the ring can easily be heard.