How can you measure forces acting between two components within a device without drilling holes or sticking on a sensor? Researchers at the Technischen Universität Darmstadt, Germany, have developed a simple solution: a screw with an integrated sensor.

The researchers say that adhesive compounds dissolve easily, and externally mounted sensors provided readings from “outside” but could differ from the forces actually acting in the interior of a machine or a component. So, they asked, why not combine a sensor and an machine component such as a screw using metal-forming?

The advantages are obvious: screws are available practically everywhere and could be replaced by their “sensing” counterparts in entire production chains. Their operation is very simple and the little “measuring device” is hardly prone to faults. The sensor is located exactly where the forces are acting and therefore works very precisely, so that designing and dimensioning can be carried out more efficiently.

The sensor screw can provide measurement data at certain points in time, but also continuously. Among other things, this makes precise quality controls possible. For example, if a workpiece that is deformed or whose thickness varies is being transported through a roll train, the sensor screws that hold the rollers would register it immediately. Until now, quality-reducing deviations often become apparent only during the final inspection after the entire production process, resulting in expensive rejects.

In order to be able to read and interpret the measurement data of the sensor screw, the researchers are developing suitable analysis software. The screw has passed through several stages, was made smaller, is approaching marketability and has been patented.