Surface speed of iglidur materials

Surface speed
The peripheral speed is always important for plain bearings. The absolute speed is not crucial, but the relative speed between the shaft and the bearing.

The surface speed is expressed in metres per second [m/s] and calculated from the speed n [UPM] with the following formula.

Rotations: v = n d1 π/(60 * 1,000)[m/s]

Pivoting movements: v = d1 π 2 * β/360 * f/1,000[m/s]

In these equations:

Permissible surface speeds

iglidur plain bearings have been developed for low to medium surface speeds in continuous operation.

Tables 01 and 02 show the permissible surface speeds of iglidur plain bearings for rotating, pivoting and linear movements.

These surface speeds are limits assuming minimal pressure of the bearings.
In practice these limits are not often reached due to the alternating effect of influences. Each increase in pressure leads unavoidably to a reduction of the permissible surface speeds and vice versa.

The speed limit is determined by the bearing's temperature increase. This is also the reason why different surface speeds can occur for the different movement types.
With linear movements, more heat can be dissipated via the shaft as the bearing uses a longer area on the shaft.

Surface speed and wear

Considerations regarding the permissible surface speeds should also include the wear resistance of the plain bearings. High surface speeds automatically result in correspondingly high wear rates. With higher surface speed, not only the wear rate rises but also the absolute wear.

Surface speed and coefficient of friction

In practice the coefficient of friction of plain bearings is a result of the surface speed. High surface speeds have a higher coefficient of friction than low surface speeds. Diagram 01 shows this correlation by using the example of a steel shaft (Cf53) with a load of 0.7MPa.

Tested in the test laboratory for use in the real world