plaquette MACHLINE - Ntn-snr.com
plaquette MACHLINE - Ntn-snr.com
plaquette MACHLINE - Ntn-snr.com
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VG 15<br />
VG 150<br />
VG 68<br />
VG 46<br />
VG 32<br />
VG 22<br />
- Coefficient a 3<br />
Coefficient for correcting calculations according to<br />
operating conditions: contamination, lubrication,<br />
temperature... Please note that coefficients a 2<br />
and a 3 are not independent.<br />
- Coefficient a 3pol<br />
Contamination can reduce service life, depending<br />
on its type and the level at which the rotating<br />
parts are loaded.<br />
In most cases, a spindle bearing operates in<br />
maximum cleanliness conditions, and coefficient<br />
a 3pol will thus equal 1.<br />
For other types of<br />
applications which are<br />
Filtration<br />
< 3 µm<br />
a 3pol<br />
1<br />
less well protected,<br />
5 µm 0.95<br />
coefficient a 3pol can<br />
10 µm 0.90<br />
have the following values:<br />
- Coefficient a 3lub<br />
Bearing service life is influenced by the efficiency<br />
of lubrication, which, amongst other things, is<br />
characterized by the oil film thickness. Elastohydrodynamic<br />
theory shows that this latter value<br />
depends almost entirely on oil viscosity and<br />
speed. The graphs below can be used to determine<br />
coefficient a 3lub .<br />
Kinematic<br />
viscosity<br />
(cSt<br />
or mm 2 /s)<br />
Graph 1: viscosity-temperature<br />
SAE 50<br />
SAE 40<br />
SAE 30<br />
SAE 20 W<br />
SAE 10 W<br />
ISO<br />
viscosity<br />
16<br />
VG 680<br />
VG 460<br />
VG 320<br />
Operating temperature (°C)<br />
21
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