The time for heating begins: polymer ball bearings from igus® defy extreme heat

Patrick Czaja | 27. October 2020

Plastics and hot temperatures in ovens do not have to oppose each other, as shown in the following application example of the Koppe company. This is because in their pellet stoves for private households, lubrication-free polymer ball bearings from igus are used successfully. The functionality of the stoves is ingenious, as the pellets burn without electricity via a mechanical drive unit. The polymer ball bearings ensure long operating times and smooth operation in the drive unit.

Polymer ball bearings for pellet stoves

In 2012, the Koppe company decided to launch a pellet stove on the market. The issue of sustainability played a major role, as alternative energy sources should not lead to a reduction in operating performance. A mechanical drive unit conveys the wood pellets into the combustion chamber without electricity. Burning time is around 24 hours at a heat output of 10 kW. The company was looking for a bearing for the drive mechanism that could withstand the adverse conditions.

igus quickly became the centre of attention with its xiros polymer ball bearings. Two ball bearings from igus are now used in each of the mechanical drive units, which impress with their stability. Wherever metal ball bearings quickly reach their limits, polymer ball bearings made of the company’s own xirodur materials implement many applications without lubricants or maintenance, and also do this successfully.

Koppe’s developments resulted in Gravity, a pellet stove that combines the convenience of a traditional wood stove with the comfort of pellet technology. With an efficiency of more than 80 per cent, it is the first stove of its kind to operate smoothly according to this system.

Differences to the classic wood-burning stove

Movements in the interior; this is the major difference to the pellet stove. A cylinder sitting on a roller transports the pellets from a storage container into the combustion chamber. The lubrication-free and maintenance-free xiros polymer ball bearings are used on the left and right of the roller. The temperature resistance comes from the material xirodur A500. This special variant of the material even allows short-term high-temperature applications of up to 315°C. In addition, the ball bearings are shock-resistant and guarantee long-term smooth operationas lubricating oils are not used. Metal ball bearings had no chance in comparison. Immediate seizure and a high noise level during operation were quick exclusion criteria. When it comes to smooth operation, service life, temperature resistance and insensitivity to dirt, igus is unrivalled in pellet stoves.

Why metal ball bearings are sometimes at a disadvantage: