Integrated sensors keep an eye on bearings

German researchers have developed a technique for integrating thin-film sensors into the surfaces of bearings to measure their temperatures and stresses. The researchers, from the Fraunhofer Institute for Surface Engineering and Thin Films (IST), say that their technology will give more accurate and reliable readings than, for example, thermocouples attached to bearing shells.

The technology could help to avoid unplanned downtime in applications such as machine tools.

The multifunctional sensors (shown above) are made of a low-friction, wear-resistant amorphous (non-crystalline) carbon material with a diamond-like structure. The material - which the researchers have called DiaForce - can sense force, pressure and temperature. The values are measured as changes in resistance.

Holger Lüthje, head of the IST`s sensor technology group, says that the thin-film sensing technology is "setting new standards". The sensors, he adds, will "open up completely new fields of application, making it possible, for the first time ever, to obtain local measurements in direct contact with an anti-friction bearing".

For fixed installations, the sensors can be hard-wired, while for moving parts, wireless connections are possible.