Screw load monitoring using the SPASS® washer

Bolted joints ensure function and safety in industrial applications by achieving secure and long-lasting connections between components.  The necessary bolt tension is usually established using a torque wrench, but this is an approximation at best since over 90% of the torque reading is distorted by friction on the thread and the underhead region of the bolt.

In bolted joints that are critical for safety, as well as those in cost-intensive processes, torque readings are no longer sufficient as a method of monitoring the condition of the joint.    

The SPASS^®-Dremodisc fibre-optic washer is a new clamping force sensor with integrated optical fibre (LWL) which enables it to capture the full contact pressure and therefore the true tensile stress of the bolt.

The SPASS^®-Dremodisc is used instead of the usual washer. Wireless data transmission to the torque wrench (see Fig. 2) ensures the usual easy handling of the wrench. The torque wrench has a display that shows the respective tensile stress and indicates when the pre-set tensile stress has been achieved.

Direct data transmission to the control centre is also possible using appropriate interfaces.

Preventing fatigue in wind turbines using the SPASS^®-Dremodisc washer

In wind turbines the fibre-optic washers are used to monitor the static equilibrium of the foundation (bolted joints in the tower shaft), as well as overload protection in rotor blades which are particularly affected by material fatigue.

This innovative condition monitoring system helps to organise maintenance, which ultimately leads to optimised turbine availability.  

Further information:

REMBE^®FIBRE FORCE GmbH
Gallbergweg 21
59929 Brilon/Germany
T +49 (0) 2961 74 05 – 350
F +49 (0) 2961 74 05 – 359
email: us@rembe.de
www.dremodisc.de