Ultrasonic Tightening Bolt


A bolt gets longer when when tightened in proportion to the clamp load. The clamp load can be calculated by measuring the length of the bolt before and after the tightening procedure using ultrasonic measurements. It times the reflection of high-frequency sound waves from the head of the bolt to the end of the bolt, it’s difference in reflection time telling you the direct dimension for the clamp load.

Even though this method is an excellent way to measure the real clamp load, it isn’t used in production very often because the bolts need to be grounded on both ends before they can be used for ultrasonic measurements.


Therefore, Nedschroef invented the Nedsonic bolt. This bolt features a perfectly flat area on top of the head of the bolt in order to put an ultrasonic transducer on it without grounding. Furthermore, the end of the bolt is shaped in a special way to guarantee perfect soundwave reflections.


Nedsonic tackles another problem: The tool drive of a Nedsonic tightening device has an integrated ultrasonic transducer. It enables an accurate load measurement on every bolt during tightening throughout the whole tightening range. It also facilitates immediate correction in case the bolt hasn‘t been tightened within the tolerances aimed for. And it even supports load controlled tightening.




  • Improved reliability and safety

- The tightening process is not influenced by the friction
- Every Nedsonic bolt is tightened exactly to the predefined clamp load
- Decrease in recall, product liability, warranty and repair costs


  • Increased product performance

- Size and weight reductions due to use of fewer and smaller fasteners
- Increased engine performance from improved power-to-weight ratio
- Better fuel economy from decreased vehicle weight


  • Manufacturing cost reductions

- Savings in assembly time and direct labour costs
- Savings in fastener and fastener-assembly costs due to use of fewer and smaller   fasteners
- Nedsonic bolts are available to almost the same price as standard bolts