 |
The
recommendations of this document are only a
summary of the most important precautions. All
users must strictly follow the safety
instructions existing in the laws, decrees and
technical standards of their country and in
machine instructions.
|
| Grinding wheels are
breakable, it is imperative that users take
sensible precautions. |
| Abrasive wheels
damaged, improperly mounted or used are
dangerous and can cause serious injuries to any
person in the vicinity. |
| The terms grinding
wheel or wheel used in this text mean any shape
of bonded abrasive product used on a machine:
grinding wheel, disc or segment. |
| For detailed
information about grinding wheels used on hand
held machines please see : Straight cut-off
wheels and depressed center wheels used on hand
held machines. |
| |
|
|
| 1 . Reception,
handling and storage |
| Upon delivery, the packages must
be carefully inspected, any deterioration shall
lead to a special examination of all products. |
| Always handle grinding wheels and other
bonded abrasive products with the utmost care.
They should never be dropped, knocked or rolled
along the floor without some cushioning between
the wheel and the ground. They should always be
stored at moderate temperature and humidity in
such a manner that mechanical damage is avoided
and that the items concerned are not subjected
to the damaging influences of moisture, frost,
uneven heating or cooling or aggressive
media. |
| For resin bonded wheels, use the
oldest first. |
| The illustration below
shows an example of how grinding wheels and
other bonded abrasive products should be
correctly stored. |
Rack design
suitable for storing a wide variety of grinding
wheels and other bonded abrasive
products |
 |
| |
| 2 . Selection
of the wheel |
| Carefully read the label or the
indications on the wheel and make sure that: |
| - The wheel is suitable for the
application and has the correct dimensions.
|
| - Check the max. RPM of the machine spindle on
which you will mount the wheel never exceeds the
max. RPM printed on the wheel label or on the
grinding wheel. |
| - On variable speed machines,
the speed of the wheel in RPM may be increased
as the wheel wears provided the maximum
peripheral speed (in m/s) marked on the wheel is
never exceeded. |
| Consequently, when
mounting a new wheel on such a machine, insure
that spindle speed is set at a level not
exceeding the maximum RPM marked on the new
wheel. |
| Follow any restriction of use and
any specific instruction which may be indicated
on the wheel or on attached documents. (For
instance, see pictograms on last page). |
| |
| Colour
Stripes |
| To make the identification of
the maximum surface speed easier, the wheels for
operating speeds 50 m/s and above, or their
label, are marked with diametrical colour
stripes in addition to the maximum operating
speed in RPM and m/s. |
COLOUR |
SPEED |
BLUE |
50
m/s |
YELLOW |
63
m/s |
RED |
80
m/s |
GREEN |
100 m/s |
BLUE |
YELLOW |
125
m/s |
|
| The maximum peripheral
speed corresponding to the colour stripe shall
never be exceeded. |
Side Grinding :
do not
use a straight wheel wich has a thickness of
less than 10% of the wheel diameter for side
grinding. |
| |
| 3 . Visual
inspection and ring
test |
Always carefully inspect the
grinding wheels and bonded abrasives before
mounting for possible damage.
Certain
types of wheels - particularly vitrified wheels
exceeding 80 mm in diameter - can be subjected
to a sound test. To make such a test lighter
wheels are held on a mandrel or finger and
heavier wheels are stood on a firm base and are
tapped at several points with a non-metallic
object. |
| Example of
tapping points for a ring test |
 |
| Wheels that are in good
condition ring clearly but wheels that are
damaged give a dull or chattering sound. |
| |
| 4 . Mounting |
| This operation
shall performed by a qualified trained
person. |
No
modification shall be made to the bore and/or
recess of a grinding wheel after
delivery
Follow the indications of the
machine manual and, in addition, take the
following steps: |
4.1 Machine
Inspection
Make sure that there is no
risk of accidental starting of the spindle.
Carefully inspect the mounting devices:
they must be in good mechanical condition and
free of foreign bodies such as pieces of old
blotters or grinding swarf. |
4.2 Wheel
Mounting
Certain wheels have a
positioning mark on them. Care must be taken to
ensure that this mark occupies the position
stated by the manufacturer (see examples
below). |
| Examples of the
positioning mark |
 |
4.3 Type of
mounting
Depending on the type of wheel
or other bond abrasive product, it must be
mounted by one of the following systems : |
4.3.1 Clamping flanges for
wheels that have a central bore
It should
be checked that the clamping flanges are of
equal diameter and have similarly formed
abutment faces.
The abutment faces of
the flanges must be clean, flat and without
grease. Flange diameter is generally at least
one third of the diameter of the wheel (1/4 for
straight cut-off wheels on fixed machines), and
must be recessed around the center
hole. |
 |
The wheels should be
placed on the machine shaft or securing system
without the application of force.
Where
the wheel has to be clamped between flanges by
means of bolts, they should be tightened
diagonally, using a torque wrench whenever
possible. Make sure that the nuts and bolts are
clean and in good condition in accordance with
the machine operating instructions. |
Blotters
Where grinding wheels
are mounted between flanges, blotters of soft or
flexible material such as plastic, cardboard or
rubber have to be fitted between the abutment
faces of flanges and the wheel. In the case of
fine grain grinding wheels used with a coolant
and remaining a long time in operation, it is
advisable to use blotters made of plastic or
rubber. |
| Blotters need not be fitted in
the case of grinding wheels tapered on both
sides, semi-flexible abrasive discs, straight
cut-off wheels with a thickness T not exceeding
1 mm, grinding wheels cemented to a plate, small
wheels with a diameter D not exceeding 20 mm and
honing stones. |
Reducing bushes
Where a removable bush is used as a
means of reducing the bore of a grinding wheel,
care must be taken to ensure that the annular
abutment faces of the clamping flanges do not
contact the reducing
bush. |
| Examples for the
correct use of reducing bushes |
 |
| 4.3.2 Fixed support flanges
for bonded abrasive products with central thread
inserts |
| These flanges must not be
recessed. Blotters must not be fitted. |
| Mounting system for a
type 11 tapered cup wheel with a central plug
thread insert |
Mounting system for a
type 16 with a blind hole thread insert |
|
|
|
| When bolting the wheels to the
plate the bolts must be of such a length that
they do not reach the end of the blind threaded
insert or contact the recess in the abrasive
wheel (see the above picture for type 16). |
| 4.3.3 Segments mounted on a mounting
fixture |
| Where the segments are not
provided with their own mounting elements,
blotters must be fitted to ensure that there is
no direct contact between the segments and the
supporting face of the mounting fixture. It must
also be ensured that the unsupported length Lf
of the segments does not exceed 1.5 time their
thickness
C. |
 |
| 4.3.4 Mounting of
disc wheels and cylinder wheels on support
plates |
| Disc wheels and
cylinder wheels are either cemented to or have
threaded inserts by means of which they can be
bolted to a support plate. Blotters must not be
used. When cementing abrasive wheels to the
plate care should be taken that the adhesive
applies no stress to the
wheel. |
 |
| Grinding wheel
cemented to a steel
plate |
| When bolting the wheels to the
plate the bolts must be of such a length that
they do not reach the end of the blind threaded
insert or contact the recess in the abrasive
wheel (see the picture
below). |
 |
| Grinding wheel
bolted to a backplate |
| Veiller à ce que les vis
utilisées pour les écrous noyés ne soient pas
trop longues et ne viennent jamais toucher le
fond des écrous ou des trous pratiqués dans la
meule. |
 |
| Correct nut and
bolt arrangement |
4.3.5 Fitting of
mounted wheels and points
It must be
ensured that the spindle of the mounted wheels
and points is firmly held in the chuck or
collet. |
 |
| The length of spindle in the
chuck or collet L3 for 3 and 6 mm spindles shall
be at least 10 mm and 15 mm for 8 and 10 mm
spindles. The overhang Lo applicable to the
maximum permissible speed of the mounted wheel
shall not be
exceeded. |
| |
| 5 . Before
Starting |
| Make sure that all adjustable
machine parts are set in the right position
according to the machine instructions manual. |
| Adjust the balancing device, if any, for
minimum out of balance. |
| Make sure that
the part to be ground is firmly secured. |
| The wheel guard must be adjusted to
fit the wheel to be mounted, closed and
locked. |
Personal
Protection:
Eye protection is mandatory
and, depending on the application: safety shoes,
gloves, dust masks and ear protection may also
be required.
In addition, for certain
operations, it is also necessary to wear face
protection and a leather apron. |
| |
| 6 . Operating the
Machine |
Truing and
dressing
When applicable, true the wheel
only with specially designed wheel
dressers.
If it is necessary to partially
open the guards in order to be able to dress the
wheel on the grinding machine, suitable measures
must be taken to avoid the risk of injury from
flying particles or the possible breakage of the
grinding wheel. |
Coolants and
draining
Where coolant is used, once the
grinding operation is completed, the coolant
supply should be turned off and the grinding
machine kept running at no-load until
centrifugal force has drained all the coolant
from the wheel.
If the grinding machine
is not to be used again for any length of time,
it should be ensured that the coolant is
prevented from being absorbed by the grinding
wheel.
Where resinoid-bond wheels are
used for wet grinding, it should be ensured that
the coolant has a pH value not exceeding 9 and a
temperature not exceeding 40 deg.C. |
Tape or wire bindings
Where
cylinder wheels or cup grinding wheels are
fitted with tape or wire bindings (as shown in
the illustration below), these must only be
removed once the wheel has been worn down to the
level of the tape or wire binding. |
| |
| 7 . Safety at the
Workplace |
All safety devices provided
with the grinding machines such as guards and
covers, should be utilised and should not be
modified in any way.
Where flying sparks
could prove a hazard, screens should be set up
to provide protection. Hand held grinders should
be used in such a manner that sparks fly away
from the operator's body.
Equipment
should be provided to keep the air around the
workplace clean where it would otherwise be
possible to breathe in hazardous concentrations
of dust, vapour or aerosols.
The
necessary equipment should be used to ensure
reliable extraction of grinding dust without the
risk of causing fire or explosion if the dusts,
vapours or aerosols concerned could be of a
flammable or explosive nature. |
| |
Note :
Additional safety
recommendations may be found in the FEPA Safety
Code for the use of bonded abrasives. |
