Surface speed of iglidur materials

Calculating surface speed at bearing points with rotating movement

For applications in which the shaft performs complete rotations in the bearings, the peripheral speed at the bearing's inner diameter must be calculated. The diameter of the bearing and the number of rotations per unit of time (ideally rpm) are necessary for this.

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

Formula: v(u) = π d n

Since the standard units used for plain bearings are mm and rpm, the formula requires conversion factors:

Formula with conversion: v(u) = ( π d n ) / ( 1000 * 60 )

Example

For a bearing with a 20mm diameter (d) and a rotation speed (n) of 100rpm, the calculation for surface speed is:

v(u) = π d n => v(u) = 3.142 0.02m 1.667rpm = 0.1m/s (figures rounded to two decimal places)

Surface speed at bearing points with pivoting or oscillating movement

Another frequent plain bearing operating mode is swivelling or oscillating movement. This occurs in hinges or applications with other types of pivoting movement. The shaft rotates in alternating directions at the bearing point. The angle representing the difference between the two end positions is the pivot angle. In these applications, movement frequency and pivot angle are often the only known quantities. However, the calculations for these applications also require peripheral speed, or the speed at which the shaft moves relative to the plain bearing. The formula takes into account the angle and is therefore a bit more complicated.

The formula: v(u) = (n ꞵ d * π) / 360

Here, ꞵ is the pivot angle. Adapted to bearing diameter in mm and pivot cycles per minute:

v(u) = (n ꞵ d π) / (60 1,000 * 360)

This formula can be used to calculate the surface speed for pivoting applications.