Grease life for the relubrication-free variant
- the operating temperature [°C]
the speed factor A = n dm
A = speed factor [mm/min]
n = rotational speed [r/min]
dm = bearing mean diameter [mm] (table 1)
An SKF ConCentra roller bearing unit with a plummer block housing is required for an industrial air handling unit. The following application information is known:
- required grease life L50h = 100 000 hours
- equivalent dynamic bearing load P = 7 kN
- rotational speed n = 1 800 r/min
- shaft diameter da = 60 mm
- environmental conditions: relatively clean
- expected operating temperature: 55 °C
Based on the shaft diameter provided and the plummer block housing requirement, the SYNT 60 bearing unit is selected. As the application is an industrial air handling unit in a relatively clean environment, the relubrication-free variant would be a suitable choice.
From the product table, the basic dynamic load rating C = 156 kN and
when C/P = 156/7 = 22,3
then P = 0,045 C
Therefore, the bearing unit meets the conditions of use for relubrication-free variants, where P ≤ 0,05 C.
For dm = 85 mm (table 1)
A = n dm = 1 800 x 85 = 153 000 mm/min
Using diagram 1, the intersection point of the calculated speed factor and expected operating temperature of 55 °C is located in the shaded area.
The SYNT 60 FW (or SYNT 60 LW) bearing unit meets the grease life requirement and is therefore suitable for the application.