Robust pet-tracker with sensitive insides

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Bundled ultrasonic waves through step joint design

An advantage of ultrasonic welding is the directed application of energy. In order to focus the ultrasonic waves, the components have so-called energy directors: points or edges that are designed and molded from the outset. The spot- or line-shaped contact areas prevent full-surface coupling. The melt is formed directly between the components at the contact point of the energy director. With many components, correct joint design is absolutely necessary to ensure reliable process management. The type of joint design depends on:
  • Component design (wall thickness)
  • Material properties (amorphous or semi-crystalline)
  • Filler materials (e.g. glass fibers)
  • Requirements for strength and burst pressure
For the locating device GRETA, a step joint is used - this joint variant is easy to achieve and generates strong connections with increased shearing and tensile forces. It also assists self-centering of the components in the joining process.

Step joint before welding

Preliminary tests on a prototype with the step joint

Step joint after welding

Step joint welded: here one has a very good view of the molecularly bonded, tight connection

We asked qualified industrial designer Harald Kuhn, Technical Director at Prothelis, about finding industrial partners in the design phase.

- Mr. Kuhn, how did you find the suitable joining process?

- In the development phase, we first looked at mechanical processes like gluing, screwing and clipping. Then, in the conversations with different suppliers and possible producers for our half-shells, the key phrase “ultrasonic welding” came up. The advantages sounded promising; above all we were looking for something watertight and dust-tight, but cycle times also played a role.

- Why did you choose Herrmann Ultraschall?

- We did some research on the internet and came across Herrmann Ultraschall, the website of which provided good initial information. And then the chemistry and the consulting from Herrmann were just right: both at the initial contact with Dirk Loibl and in the laboratory at Herrmann, where Norbert Friedrich looked after us. We were very satisfied – with the successful initial tests and the assistance with the constructive design of the half-shells to make them suitable for ultrasonic welding.

Welding tool sonotrode

The sonotrode weld tool shows the negative of the application

Prothelis is a promising start-up with a smart idea: the universal locating device Greta. The Global Realtime Emergency Tracking Allrounder is a perfect companion for people with special protection needs. It is also suitable for the locating of pets and livestock, and the safeguarding of valuable items. The system works with two satellite systems: GPS and Glonass. Using an app, Greta users can for example locate their four-legged friend in real time – almost anywhere in the world. In addition, virtual fences (geofences) can be set up. As soon as the tracker goes outside the geofence, or the previously set speed or temperature is exceeded, a push message is sent to the smartphone or the user is called by the 24-hr alarm service. It is not for nothing that “protecting life” is the company motto. More information at:

Herrmann Ultraschalltechnik GmbH & Co. KG