Robust maintenance-free polymer plain bearings
The photovoltaic specialist uses lubricant and maintenance-free plastic plain bearings from igus® GmbH in all its solar tracking systems. In “s:wheel” they take on a centering function above all. And in the pivoting axis of the “s:track” horizontal tilting system, they prove their strengths in many ways. Pressed into a fully galvanized standard tube, combined with a steel shaft, they must work reliably despite the prevailing installation tolerances. At the same time they tilt daily by +/- 45°. Above all this comes down to insensitivity during assembly, smooth handling and a long service life.
The systems are not always aligned to the last millimeter. “You have to take tolerances into account in steel constructions,” says Dirscherl. High forces are generated in this case, which the polymer bearings must be able to withstand. Added to that are difficult environmental conditions: accordingly, dust, sand, rain and heat must not have any effects on the functional capability of the overall system. All components must hold their own outdoors over the long term. “Should, for example, the plastic bearing assembly happen to fall onto the dusty ground during assembly, that does not play any part in its functional capability,” says the head of development. “With a sensitive ball bearing assembly, on the other hand, we would experience serious problems by now at the latest. “
Endurance tests conducted in advance
“At the focus of our overall systems is the simplicity for the user,” explains development head, Dirscherl. “Our customers are spread all over the world. We cannot replace the bearings every few months. Furthermore, we give our customers the guarantee that they can operate their plants for at least 25 years. ” The igus® technical sales consultant, Bernhard Hofstetter, reports on a service life calculation that was carried out in advance in this respect. “We incorporated all the critical plant parameters, such as temperature, friction and stress. We were able to prove that the service life of the polymer bearings far exceeds even the service life of the plant. With these results we are in a position to show that the machine elements work out for the customer. “