Bonding - More than materials | Herrmann Ultraschall

André Husson, the sonotrode whisperer: on measurements, complex components, and black magic GOOD VIBRATIONS A sonotrode vibrates 20,000 times a second; that is 20,000 Hertz (Hz). Some sonotrodes even reach 35,000 Hz or more. Despite this, they move only thousandths of a millimeter up and down – that is the whole “magic” behind ultrasonic welding technology. Sounds simple, but it is not. There’s more to it, above all a feel for the vibration tools. André Husson, who is the same age as CEO Thomas Herrmann – they are, in fact, old school friends – has been part of the Herrmann Ultraschall family since 1990. He works in the sonotrode measuring laboratory. Countless sono- trodes have gone through his hands; no error escapes his eagle eyes. “Years of experience,” he says. “I immediately see at a glance what is not right about the sonotrode.” Sono- trodes, the tools made to vibrate by ultrasonics, have become part of his DNA. André Husson lives ultrasonics, something noticed by anyone who speaks with him about the topic. FROM EXTENSIVE TEST TO COM- PUTER-SUPPORTED METHODS What excites him most is how the de- velopment of sonotrodes has changed in all the years with Herrmann. “When I started out, things were very simple with regard to the measurements; the technical possibilities were simple. To be honest, we often didn’t know what exactly we were doing,” he says, laugh- ing, and continues: “Walter Herrmann once said that what went on here was like ‘black magic.’ For this reason, he worked actively on the technology and formed a development department. This gave us the space to better exam- ine how a sonotrode is made to vibrate so that it vibrates cleanly, has a long service life, and the amplitude distribu- tion is correct.” According to Husson, before that the designers were often fumbling around in the dark. Today, the sonotrodes are calculated meticulously on the computer before they come into manufacturing. Only when everything is right can the sonotrode weld the application. “TODAY, THE SONOTRODES ARE MEASURED PRECISELY USING LASER DOPPLER VIBROMETERS – AN IMPORTANT STEP TOWARDS WELD QUALITY.” 51 50