| Key to Winterthur's Wheel Specifications |
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| 64A |
|
60 |
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H |
|
15 |
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V |
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P |
Index/Type
of Abrasive |
|
Grit Size |
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Wheel Grade |
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Wheel Structure |
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Type of Bond |
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Special Symbols |
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| Vitrified |
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very |
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extremly |
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natural |
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V |
vitrified |
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P |
porous |
| bonds |
|
coarse |
|
soft |
|
porosity |
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|
bond |
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|
structure |
| C |
|
12 |
|
C |
|
1 |
|
BW |
resin |
|
L |
low |
| 11C |
|
14 |
|
D |
|
2 |
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|
bond |
|
|
porosity |
| 27A |
|
coarse |
|
very soft |
|
3 |
|
BFW |
resin |
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M |
medium |
| 28A |
|
16 |
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E |
|
4 |
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bond |
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porosity |
| 29A |
|
24 |
|
F |
|
5 |
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reinforced |
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H |
high |
| 31A |
|
36 |
|
soft |
|
6 |
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porosity |
| 42A |
|
medium |
|
G |
|
7 |
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HH |
very high |
| 49A |
|
46 |
|
H |
|
8 |
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porosity |
| 53A |
|
54 |
|
J |
|
9 |
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GG |
very large pores |
| 57A |
|
70 |
|
medium |
|
10 (puddled wheel) |
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G |
large |
| 61A |
|
80 |
|
hard |
|
porous |
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pores |
| 62A |
|
fine |
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K |
|
structures |
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F |
fine |
| 63A |
|
90 |
|
L |
|
11 |
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pores |
| 64A |
|
100 |
|
M |
|
12 |
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FF |
very fine |
| 65A |
|
120 |
|
hard |
|
13 |
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pores |
| 67A |
|
150 |
|
N |
|
14 |
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SR |
special |
| 69A |
|
220 |
|
O |
|
15 |
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formula |
| 77A |
|
very fine |
|
P |
|
16 |
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| 92A |
|
240 |
|
Q |
|
17 |
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| 93A |
|
280 |
|
very hard |
|
18 |
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| resin |
|
400 |
|
R |
|
19 |
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fahren |
| bond |
|
500 |
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S |
|
20 (puddled wheel) |
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| C |
|
600 |
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T |
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| 11C |
|
800 |
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| A |
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| 31A |
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| 42A |
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| AC |
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| ZA |
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| resin |
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| bond |
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| reinforced |
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| C |
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| A |
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Hardness
The term "hardness of grinding wheels" does not refer to the abrasive grain, but designates the resistance odf the bond to grains being removed during the grinding process. |
Grain Size
The assignement of numbers to specific grain size distributions has been determined on the basis of an internationally applicable standard. Extremly fine grains (micro-grains: approx. grain 240) are otained by sedimentation. Finer grains are less brittle and harder to break out of a bond. For this reason, a wheel with fine grains appears harder than a wheel within the identical range of wheel hardness but with coarse grains. |
