Grinding wheel for grinders in factories

grinding

1. 1

2. 2
Purpose
Use of Abrasive Wheels & Grinding Machines in
construction operations.

To ensure Abrasive Wheels & Grinding Machines does not
give risks to Health and Safety regardless of:-
• Age
• Condition
• Origin

3. 3
This course will give advice on the
prevention of accidents when using
Abrasive Wheels, in particular:-
• Injury from breakage
• Injury from contact
• Injury from noise
• Injury from dust & Fume
The impact of Noise, Vibration and
Dust will also be discussed.

4. 4
The Risk of Breakage is inherent in every Abrasive Wheel
It is prevented by:-
• Care exercised in design, in manufacture and testing
• Safe measures by users.
• Injury statistics show that nearly half of accidents are
due to an unsafe system of work or operator error.

5. 5
Course Content Course Duration - 1hr
• Hazards and risks arising from use of Abrasive
Wheels and the Control Measures.
• Inspection and Test.
• Functions of Components - flanges, guards etc.
• Proper PPE/RPE.
• Health Risks - Noise Dust Vibration.

6. 6
Abrasive Wheel Classifications
An Abrasive Wheel is a wheel consisting
of Abrasive particles bonded together with
various substances:-
• Organic
• Inorganic

7. 7
50 m/s
WHEEL MARKING
63 m/s80 m/s100 m/s
Wheel Size
Max. speed in r.p.m
Standards & regulations
DSA : Germany
SUVA : Switzerland
KDM : Austria
A
B
R
A
S
IV
E
W
H
E
E
L
S
Manufacturer
Abrasive Wheel code

Max. working speed

8. 8
IDENTIFICATION OF ABRASIVE WHEEL
Order of
marking
Aluminium Oxide
Abrasive - A
Silicon Carbide
Abrasive -C
Coarse Medium Fine Very
fine
8 30 70 220

10 36 80 240

12 45 90 280
14 54 100 320
16 60 120 400
20 150 500
24 180 600

1
Nature of
Abrasive
A - C
2
Grain Size
36
3
Grade
L
4
Structure
5
5
Nature of
Bond
V
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
SOFT MEDIUM HARD
V - Vitrified
S - Silicate
R - Rubber
B - Resinoid
(Synthetic resin)
BF - Resinoid

(Reinforced
synthetic resin)
RF - Rubber Reinforced
E - Shellac
M - Magnesia
Spacing From The
Closest To Open
0 5 10
1 6 11
2 7 12
3 8 13
4 9 14

9. 9
TYPES OF GRINDING WHEELS
A
B
R
A
S
IV
E
W
H
E
E
L
S

10. 10
TYPES OF GRINDING WHEELS
A
B
R
A
S
IV
E
W
H
E
E
L
S

11. 11
A
B
R
A
S
IV
E
W
H
E
E
L
S
TYPES OF GRINDING WHEELS

12. 12
SAFETY - Wheel Breakage
Abrasive Wheel Manufacturers
carry out tests and inspection to
ensure the integrity of their wheels.
They will also reinforce wheels.
Resin coated glass fibre mats are
used in organic wheels to help
withstand high stresses and to
contain fragments

13. 13
SAFETY - Wheel Breakage
Breakage may occur in service due to:-
• Bad storage and handling
• Incorrect selection of wheel
• Improper mounting
• Excessive imbalance
• Excessive speed
• Grinding machine defects
• Malpractice
Two or more factors may act together.

14. 14
TAP
HERE
RING TEST FOR GRINDING WHEELS
If the wheel is a small one, suspend its from its hole by a small
pin or a finger.
If heavy, support it on a clean and flat surface.
Lightly tap with non-metallic tool.
45
o
45
o
Centre line
45
o
45
o
Centre line
A
B
R
A
S
IV
E
W
H
E
E
L
S

15. 15
Examination of Wheels
• Visual check
• Check classification for
suitability
• Ensure suitability for
grinder - depressed centre or flat?
• Ensure suitability for task
grinding or cutting?
• If in doubt consult Supervisor

16. 16

17. 17
HAZARDS
• Noi
se
• Du
st and Fume
• Vib
ration
• Co
ntact with
W
heel
• W
heel Breaking
• Ri
sk to others

18. 18
Noi
se
• Depe
nds on
wo
rkplace
• Depe
nds on
m
aterial
• G
rinders Always
Abo
ve 70db
• u
se protection
• t
hink of others in
a
rea
• m
anage PPE

19. 19
Du
st and Fume
• d
epends on
e
nvironment
• d
epends on material
p
aint removal
c
hemicals,
tempe
rature
• we
ar PPE/RPE

20. 20
Vib
ration
• u
se low vibration
tool
s
• keep
hands warm
• d
on’t grip too hard
• m
aintain circulation
• r
eport problems
• d
o not apply
ex
cessive
p
ressure

21. 21
Co
ntact with Wheel & Job
• pl
an the job
• get i
n a good balanced
po
sition
• d
on’t over reach or
s
tretch
• d
on’t use unsuitable access

22. 22
W
heel Breaking
• C
hoOse, right wheel for the
t
ask.
• d
on’t bend or stress wheel.
• e
nsure disc is compatible with
g
rinder.
• e
nsure disc is correctly fitted.
• we
ar correct PPE for the task

23. 23
Ri
sk to others
• pl
an the job
• c
onsider barriers
• u
se sheeting or tents if
po
ssible

24. 24
SPINDLE SPEED
• Peripheral speed on a fixed speed spindle
will decrease as diameter of wheel shrinks.
• Tendency to use more force - may cause
breakage, Change disc before it gets to low.
SPEED REDUCES
TEND TO USE MORE PRESSURE

25. 25
FLANGES
Stresses on an Abrasive Wheel
are greater nearer the hole.
Hence flanges are fitted.
Flanges should be at least one
third diameter of wheel.
Therefore if unreasonable side
force is applied disc may break
Or disintegrate near centre.
STRESS
INCREASES

26. 26
G
Type 41
G
Type 42
Reinforced resin bonded wheels
Cutting or Grinding
Flat or depressed centre
Up to 230mm diameter
Portable Machines
May have smaller flanges

27. 27
Securing the Wheel
Fit freely but not loosely - if tight,
spindle
could expand and crack wheel.
Central nut fixing - only tight enough
to
prevent wheel slipping
WHEEL
KEYS
After mounting
check speed
marked on
wheel
or blotter is not
exceeded by
that marked on
spindle.

28. 28
Summary of Wheel Mounting Procedures
• Trained Person
• Compatible Machine
• Inspect for damage
• Flanges correct for wheel
• Wheels and flanges free from
foreign matter

29. 29
GUARDS - three main functions
1.To contain wheel if it bursts
2. To prevent operator coming in
contact with wheel.
3. Also protects wheel from
damage
and prevents fitting of oversize
wheel.

30. 30
Guards - for portable machines
Enclosure 175
0
Front Lip 5mm

31. 31
PORTABLE AND
HAND HELD GRINDING/CUTTING
MACHINES

32. 32
PORTABLE AND HAND HELD GRINDERS
• Only organic bonded wheels to be used.
• Cutting wheels should have fibreglass
reinforcement.
• Machine guards must be securely in place
• Guard between user and rotating wheel.
• Serious often fatal incidents, when guard
removed to allow larger wheel to be
fitted.

33. 33
ELECTRIC GRINDERS
• Damaged cables are not to repaired
under any circumstances
• Plug and sockets compatible
• Regular Inspections by competent
electrician
• Do not try to repair, return to stores
• Always inspect daily before use

34. 34
SUMMARY OF PRECAUTIONS
• Training
• Housekeeping
• Mounting of Wheels
• Speed
• Guards
• Rests
• Lubrication
• New Wheels
• Stopping Wheels
• Overhang on Mounted Wheels