Damage patterns of plain bearings – Part 1: Deformations

Lars Butenschön | 14. December 2022

Damage to plastic plain bearings is often the result of improper assembly, incorrect structural design or incorrect material selection. On the one hand, the nature and mode of operation of the plastic plain bearings place some demands on the dimensioning, design and assembly of the bearing point. On the other hand, compared to metallic bearings, a more flexible design of the component geometry and a “more creative” or potentially riskier design is possible.

The various damages to plastic plain bearings can generally be easily distinguished from one another. As a result of the appearance of the damage, e. g., deformation or cracks, its cause can be inferred. In this blog post, we give you an insight into the white paper “Typical damage patterns – How to avoid premature failures of plastic bushings” with an excerpt that goes further on the topic.

Detect deformations

Deformations occur mainly in case of overload. Overload deformations can often be recognised as relatively uniform deformations at the stressed points of the plain bearing. If the load applied by the shaft exceeds the permissible surface pressure of the bearings, or if excessive edge loads occur due to acting torque, the bearing is deformed in the direction of this load.

This is referred to as “creep” of the material. This creep occurs when the component is constantly under very high tension. Exposure to temperature – either due to excessive friction or external influences can promote and accelerate this process if it exceeds the thermal resistance of the plastic.

How we solve the problem

Fibre-reinforced polymers can generally take higher loads. In this respect, they are preferable for applications with high loads. Increasing the bearing diameter can also help to reduce the surface pressure. In addition, unwanted edge loads, e.g. as a result of misalignment, should be avoided by precise alignment of the components or by self-aligning.

In addition to the deformation, there are of course other types of damage that can be observed in practice. In our white paper “Typical damage patterns – How to avoid premature failures of plastic bushings” you will find more useful information on this.