Corrosion-free bearings for ring motors in underwater vehicles and boats

Profile

• What was needed: iglidur plain bearings
• Requirements: The ring motor and bearings are permanently under water. The bearings must therefore be able to function permanently despite high salt content and possible contamination. In addition, the lightest possible bearings were sought, as any additional weight would have to be compensated for by increasing the size of the drive.
• Industry: Shipbuilding
• Success for the customer: The polymer bearings proved to be the best solution for the application: in contrast to metallic solutions, they are corrosion-free and lightweight. And compared to ceramic bearings, they have a higher load limit and are highly wear-resistant. 

Problem

With ring motors (torque motors), there is no mechanical connection between the rotor and stator during operation. The magnetic ring (rotor) is only centred by the magnetic field of the stator and held in the magnetic field. A bearing for the magnetic ring is therefore only necessary during the start-up phase of the motor.
However, the demands on the bearing point are exceptionally high due to the special environmental and operational situation. This means that the ring motor and bearing points are permanently under water and are exposed to high salt content, corrosion and possible contamination. It was also important to find bearings that were as light as possible, as any additional weight in the water had to be bought at a high price by increasing the size of the drive.

Solution

The designers finally decided in favour of using iglidur bearings in the ring motors, which were able to solve the problems permanently. The polymer bearings are suitable for use in and on underwater vehicles and boats due to their corrosion resistance, low moisture absorption and lightweight property compared to metallic solutions. Compared to ceramic bearings, the iglidur bearings also offer the advantage that they have a high load limit and are highly wear-resistant. While initial tests with impacts caused problems with the ceramic bearings, the special bearings made from high-performance polymers remained dimensionally stable over the long term. Another important criterion for dynamic fields of application.