Friction and lubrication

Bearing friction torque

The friction torque of the bearing is made up of several components and is essentially determined by:
■ Bearing preload
■ Viscosity of the lubricant
■ Quantity of lubricant

Bearing preload

A lower bearing preload generates less friction and therefore lower temperatures, and is always better for high-speed applications. Here it must be observed that the bearing preloads are always sufficient for backlash-free operation of the bearing under load.

A higher preload provides higher rigidity but at the same time also adds more friction to the bearing.

Viscosity of the lubricant

The viscosity is dependent on the operating temperature and of course on the selected lubricant. An excessively low viscosity leads to mixed friction, in particular in case of low-speed or intermittent operation. Excessively high viscosity, on the other hand, leads to high friction, in particular in high-speed applications.

Lubricant quantity

Excessively high lubricant quantities increase the bearing friction significantly. myonic cages are designed to absorb as high a lubrication quantity as possible and to emit the lubrication directly onto the rollers during operation. During run-in or during relubrication, the appropriate run-in cycles must be adhered to.

Commissioning

In case of grease lubrication, a run-in cycle is to be run during commissioning in order to distribute the grease in the bearing. Only after complete distribution does the bearing achieve full functionality. In case of incorrect execution of the run-in cycle, high friction torques may occur which overheat and damage the bearing.

In case of existing temperature monitoring, the run-in cycles can be adapted. A maximum ring temperature of 60°C may not be exceeded. If you hear running noises, stop immediately and leave to cool down.
In case of slow-running swivel axes, the run-in cycle does not have to be conducted.

Relubrication

Relubrication briefly increases the amount of lubricant in the bearing until the grease is distributed and the excess amount has escaped from the bearing.

In the case of high relubrication quantities or unregulated relubrication, a run-in cycle must be run in order to distribute the grease in the bearing.

AXRY axial-radial bearings of the design EX, NGX, NGS as well as crossed roller bearings AXCR can be relubricated via a lubrication groove in the outer ring.

The NGX and NGS bearing types have an additional lubrication connection in the bearing screw mounting surface of the outer ring. This enables reliable lubricant supply even with a large clearance fit in the bearing seat or an unsupported outer ring. In addition, we offer the lubrication option via a lubrication groove on the inner ring with the suffix -SBI.

For relubrication through the lubrication groove of the outer / inner ring, we recommend to fill the lubrication groove completely with grease before assembly of the bearing. This way grease will enter the bearing faster in case of a relubrication process. The lubrication channel of the housing additionally should be close to the radial lubrication hole of the bearing.

The AXDR series can be relubricated via two grease nipples attached to the outer ring by the customer.

You can receive information on relubrication intervals and quantities from myonic application engineering.