Smart screw connection – Wireless and energy-autonomous monitoring solution

The remotely monitored screw connection detects the preload force – wirelessly and with an energy-automomous supply. A thin-film sensor system integrated into the screw detects minimal variations of the preload force and transmits them wirelessly to a control body.
© Fraunhofer IIS
The remotely monitored screw connection detects the preload force – wirelessly and with an energy-automomous supply. A thin-film sensor system integrated into the screw detects minimal variations of the preload force and transmits them wirelessly to a control body.
Das 9. Ziel für nachhaltige Entwicklung der UN: Industrie, Innovation und Infrastruktur.

Challenge

A drop in the pre-tensioning force can have serious consequences for load-bearing elements that are subjected to heavy mechanical or thermal loads. Safe operation can then no longer be guaranteed. For this reason, a screw connection should be developed as a completely integrated IoT device for energy-autonomous, wireless, tamper-proof monitoring.

Solution

At the Fraunhofer IST, a thin-film system for force and temperature measurement was deposited on the surface of washers. This system was integrated into screw connections and combined with wireless transmission technology and energy harvesting technologies. The thin-film system consists of the piezoresistive DiaForce® layer and the electrically insulating and wear-resistant SiCON® layer. These are deposited by means of the PACVD process. In between are sensor structures made from chromium and manufactured by means of microstructuring. The total thickness of the system is approx. 10 µm.

Added value

With the “intelligent screw connection”, wireless, eenergy-autonomous monitoring of the preload force is possible with the help of a retrofittable sensor system for DIN screws during assembly and operation. Deviations can be detected immediately via remote maintenance and downtime or maintenance times can be avoided – a complete control of critical screw connections.

Monitoring of screw connections – wireless, energy-autonomous and retrofittable.
© Fraunhofer IIS
Monitoring of screw connections – wireless, energy-autonomous and retrofittable.
Changes in the preload force can easily be read out wirelessly.
© Fraunhofer IIS
Changes in the preload force can easily be read out wirelessly.
Washer with thin-film system manufactured at the Fraunhofer IST. Three force measuring points are structured.
© Fraunhofer IST
Washer with thin-film system manufactured at the Fraunhofer IST. Three force measuring points are structured.
Schematic of the multifunctional coating systems.
© Fraunhofer IST, Falko Oldenburg
Schematic of the multifunctional coating systems.

Further information

 

Interview

Watch this interview on the most important questions regarding the “Smart screw connection”, for example which technologies are utilized, what the advantages of their use are, and which applications can be considered:

 

Project website

Funding reference

This solution is being developed within the framework of the Fraunhofer research center IoT-COMMs in collaboration with the Fraunhofer institutes IIS, IST, LBF and AISEC. FIoTCOMMs is part of the Fraunhofer-Gesellschaft's cluster initiative CCIT (Cluster of Excellence Cognitive Internet Technologies).

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