Preload force measuring system flexSonic

The functional principle of a screw connection consists in pressing the parts to be connected together. The process force essentially results from the preload force of the screw. The preload force is the quality-determining parameter for every screw connection. Screw breakage or loosening of the screw connection are the two extreme consequences of an incorrectly set screw preload force.

It is generally accepted that the influence of the strain or stress caused by the preload force on the propagation times of ultrasonic waves offers the possibility to determine the preload force, the strain or the elongation of a bolt. In combination with the so-called "acousto-elastic effect", our flexSonic system controls the screwing tool depending on the screw preload force. You can use your standard screws and do not have to use any special (expensive) screws.


  • Evaluation of the ultrasonic propagation by using selected ultrasonic transducers
  • Integration of the ultrasonic transducer in the socket, taking into account the suitability for large-scale production
  • non-contact signal transmission module · automated measurement and evaluation
  • Control of the screwing tool or the screwing process based on the recorded runtime measurement results
  • continuous comparison with calculated characteristic

Technical details as well as descriptions of the system and the process are contained in the special EST flexSonic brochure.

Click here to request

Your contact
at EST Technologie


Phone: +49 7367 923 92-0
Mail: info@est-technologie.de

Our products

Versatile drive options for accurate
geometric requirements and
custom sensor technology for reliable results.

Schmid Maschinenbau Logo EST Logo Market CleanTec Logo Schmid Maschinery Logo