For many years, the Bruchsal-based company SEW-Eurodrive GmbH & Co. KG has been looking closely at Wiegand sensors, which are non-contact revolution counters that are self-sufficient in terms of energy requirements. One unique feature of Wiegand sensors is that they go beyond emitting signals and can actually be used as an energy source. They work by using energy-rich impulses, which are independent of the actual number of revolutions but are enough to run ultra-low power electronics. For example with electric motors, this makes it possible to measure axle revolutions without any external power input. At the heart of the sensor lies a Wiegand wire, which was originally patented by John Wiegand in 1978. Made of thin metal consisting of a ferromagnetic alloy, when a Wiegand wire is subjected to special cold forming processes it can adapt properties, allowing it to spontaneously change its magnetic axial orientation.
Working with the Steinbeis Transfer Center Material Development and Testing (WEP), the team at SEW-Eurodrive has successfully developed quality analysis methods that allow the firm to significantly improve energy yields, simultaneously optimizing the manufacturing process and delivering results that are entirely reliable. Using a specially developed preparation technique, the Steinbeis experts were able to map the different magnetic zones of wires and for the first time their results have been published in the world of research. Further experimentation was carried out with carefully prepared material samples to systematically analyze microstructures deep down inside Wiegand wires in order to yield insights into the complete range of properties (mechanical, thermal, magnetic). It was important to gauge the overall picture, but this was only possible by combining a large number of material testing techniques, all of which were offered by the WEP through the material testing labs at Pforzheim University.
The project partners have been working continuously on the initiative for some time and their increasingly close alliance has now been rewarded with the Steinbeis Foundation`s Transfer Award – Löhn Award. As a result of the collaboration, Wiegand wires can now be produced in unprecedented quality, offering every potential to revolutionize the angular position sensor market in the near future.
Prof. Dr.-Ing. Norbert Jost & Prof. Dr.-Ing. Gerhard Frey
Steinbeis Transfer Center Material Development and Testing (WEP), Wiernsheim