Abrasive wheels are used across many industries, this can include manufacturing, fabrication and construction.
The use of abrasive wheels can be extremely dangerous and as there are many different types of abrasive wheels and correspondingly uses of abrasive wheels. It is important that any one using an abrasive wheel, uses the correct wheel to do the correct function and fit it to the correct tool.
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One way of making sure this happens, is by selecting the correct type of abrasive wheel for your machinery and to select the correct abrasive wheel to carry out specific grinding or cutting actions.
Manufacturers of abrasive wheels assist you in choosing the right abrasive wheel by providing them with a marking system. The marking system in the UK conforms to the standard which is set by the British Standards Institution (BSI), and the marking system is specified in BS EN 12413, “Safety requirements for bonded abrasive products“. The marking system is also standardized by the European Standards which specify the type of information that must be included on abrasive wheel labels.
This labelling system which is used, indicates:
1. Manufacturers trade mark
2.Test Record
3. Any restrictions of use #
4. Expiry Date (for organic bonded wheels)#
5. Speed Stripe#
6. Dimensions#
7. Specification Mark#
8. Code number
9. Maximum Operating Speed#
10. Type (BSEN12413) #
#Safety Related Markings
Expiry Date – often overlooked
Organic bonded wheels for hand held applications have a “use by date” of three years from manufacture
Restrictions of use (annex A BS EN 12413(3) & BS ISO 525(5)
Indicates specific operating restrictions of the abrasive wheel
RE1 Not permitted for hand held grinding
RE2 Not permitted for hand held cutting off
RE3 Not suitable for wet grinding
RE4 Only permitted for totally enclosed working area
RE6 Not permitted for face grinding
These markings help ensure the safe use of abrasive wheels in grinding and cutting applications.
Maximum Operating Speed and Speed Stripes
The maximum permissible speed is show in revolutions per minute (RPM) and metres per second (m/s) specified by manufacturers and should be marked on every abrasive wheel larger than 80mm in diameter, or on the supplied blotter or identification label.
As it is difficult to mark smaller abrasive wheels, the maximum permissible speed in RPM of wheels 80mm in diameter or less should be stated in a notice and posted near abrasive wheel machinery, where it can be read by the operator. For speeds 50m/s and above, colour coded speed stripes will appear on the wheel.
The colours are:
50m/s – Blue
60m/s – Yellow
80m/s – Red
100m/s – Green
125m/s – Blue/Yellow
Dimensions
The dimensions of the grinding wheel are marked in mm. For example, 610 x 80 x 254mm. This represents the wheel’s diameter x thickness x hole size.
Specification Mark
The specification markings carry designations for different types of abrasives, bonds, grains sizes and hardness.
The information is always represented in the same order below.
1)Type of grit
2) Size of grain
3) Hardness of grain
4) Structure
5) Type of Bond
6) Manufacturers Record
Type of Grit
A – regular aluminium oxide
WA – white aluminium oxide
19A – mixture of A and WA
SD – synthetic diamond
ASD – synthetic diamond, metal coating
FA – semi-friable aluminium oxide
PA – pink aluminium oxide
SA (HA) – single crystal aluminium oxide
23A – mixture of A and SA
AZ – zirconium oxide
C – black silicon carbide
GC – green silicon carbide
RC – mixture of C and GC
| COARSE | MEDIUM | FINE | VERY FINE |
| 8 | 30 | 70 | 220 |
| 10 | 36 | 80 | 240 |
| 12 | 46 | 90 | 280 |
| 14 | 54 | 100 | 320 |
| 16 | 60 | 120 | 400 |
| 20 | 150 | 500 | |
| 24 | 180 | 600 |
Hardness of Grain or Grade
(Soft) (Medium) (Hard)
A B C D E F G H J K L M N O P Q R S T U V W X Y Z
Structure
Close Open
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Type of Bond
V – vitrified
B – resinoid
R – rubber
O – MgO
E – epoxy
M – metal
EP – electroplated
A30SBF as an example
Grit = Aluminium Oxide
Grain Size = 30 Medium
Hardness of grain = S which is Medium
Bond = B which is Resinoid
There are a wide range of tools and processes that use abrasive wheels and ensuring these are used correctly and safely is of paramount importance.
Applications range from hand grinding to disc cutting. They can be used at all stages of a work process, for making preliminary cuts and scores in materials, or for fine polishing and finishing.
Different wheels will have different properties and characteristics suitable for particular tasks. They also have different weaknesses and can pose different risks and hazards in handling and use.
For this reason, it’s important that you always select the right abrasive wheel for the job and use it with the right machinery.
If you or your staff work with abrasive wheels, then having the knowledge on markings is essential. But, all operators should be aware of the hazards in using abrasive wheels, knowledge on different types, methods of handling as well as proper storage, inspection and relevant control measures to safeguard their use in the workplace.
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