Preload force measuring system flexSonic

The operating principle of a screw connection exists in pressing the parts to connect. The process force is mainly due to the pre-tensioning force on the screw. The pre-tensioning force is the quality-determining characteristic for each screw connection. Breaking the screw or having a loose screw connection are the two extreme consequences of an incorrectly adjusted screw pre-tensioning force.

It is generally accepted that the influence of the elongation or tension caused by the pre-tensioning force on the rotations of ultrasonic waves offers the possibility to determine the pre-tensioning force, the elongation or the extendibility of a screw. In combination with the so-called "acoustoelastic effect", our flexSonic system controls the screwdriving tool depending on the pre-tension screw force. Therefor you can rely on your standard screws and no need to use special (expensive) screws.


  • Evaluation of ultrasonic wave propagation using specific ultrasonic transducers
  • Integration of the ultrasonic transducer into the screwdriver nut with consideration of suitability for volume production
  • Non-contact signal transmission, automated measurement and data analysis
  • Control of screwdriver and screw driving process unsing the recorded run time measurement results
  • Continuous comparison with estimated characteristic diagram

For technical details and descriptions of the system and the process please refer to specific EST flexSonic brochure.

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Mail: info@est-technologie.de

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