Housings and Shafts
Housing
and shaft tolerances and surface finishes.
Metal
mating surfaces must be suited to the wear conditions encountered,
for example when operating in sandy conditions. Hard shaft surfaces
ensure longer shaft and bearing life. Designing bearings for
dirty
conditions required additional attention.
Hard chrome plated surfaces, seawater corrosion resistant stainless steel and admiralty and gunmetal bronze liners are generally satisfactory as mating surfaces for Vesconite.
Carbon steel and hardened steel shafts may be used as mating surfaces provided that they do not corrode under the conditions of use.
Metal
tolerances
Standard
steel tolerances can be used with Vesconite bearings.
Housings
: H7
Shafts
: h7
|
|
Housing / shaft diameter in mm (ISO tolerances) |
|||||||||
|
Diameter in mm |
10 - 18 |
18 - 30 |
30 - 50 |
50 - 80 |
80 - 120 |
120 - 180 |
180 - 250 |
250 - 315 |
||
|
Housing |
H7 |
Upper |
+ 0.018 |
+ 0.021 |
+ 0.025 |
+ 0.030 |
+ 0.035 |
+ 0.040 |
+ 0.046 |
+ 0.052 |
|
Lower |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
||
|
Shaft |
h7 |
Upper |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
Lower |
- 0.018 |
- 0.021 |
- 0.025 |
- 0.030 |
- 0.035 |
- 0.040 |
- 0.046 |
- 0.052 |
||
|
|
Housing / shaft diameter in inches |
|||||||||
|
Diameter in inches |
0.4 - 0.7 |
0.7 - 1.2 |
1.2 - 2.0 |
2.0 - 3.15 |
3.15 - 4.72 |
4.72 - 7.1 |
7.1 - 10.0 |
10.0 - 12.4 |
||
|
Housing |
H7 |
Upper |
+ 0.000 71 |
+ 0.000 83 |
+ 0.001 0 |
+ 0.001 2 |
+ 0.001 4 |
+ 0.001 6 |
+ 0.001 8 |
+ 0.002 1 |
|
|
|
Lower |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
Shaft |
h7 |
Upper |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
Lower |
- 0.000 71 |
-0.000 83 |
- 0.001 0 |
- 0.001 2 |
- 0.001 4 |
- 0.001 6 |
- 0.001 8 |
- 0.002 1 |
||
Surface
finish
Housings
The
surface finish on the housing is not critical as there is no movement
after installation. For the purpose of installing the bearing the cut
must not be too coarse. Lead in chamfers are required to ensure that
the bearing does not score when been installed.
Shafts
The
surface finish of the shaft is very important to ensure a correct
operation of the bearing.
A
good finish of the order of 2.5 µm Ra (20 micro inch Ra) should
be provided on shaft surfaces for an optimum wear life. For shafts
with an axial motion relative to the bearing, a finish of the order
of 0.5 µm Ra (20 micro inch Ra) should be provided on shaft.
Rough
surface finishes and corroded and scored shafts will cause wear of
Vesconite bearings and should be avoided.
| Click picture for Smoothness Table | Click picture for Hardness Table |
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Designing for dirty conditions
Updated Jun 01 2005
