All thermoplastic resins can be welded using ultrasonics. Best are hard, amorphous plastics such as PC, PS, SAN, ABS, and PMMA. They have ideal transmission properties for ultrasonic energy, thus they are also easily weldable and achieve good results even with larger dimensions. Semi-crystalline plastics, such as PA, PP, PE, and POM melt generally faster. Consequently they can only be welded within the near field of the sonotrode (weld tool).
Ultrasonic welding is a fast and economical, but also complex technology. To evaluate a welding task you need experts. In the lab, our engineers test the feasability of the application: Is the material weldable? Is the component design adequate? Is there a proper energy director, that will focus the ultrasonic waves to define the melt initiation?
Ultrasonic engineering includes all services to ensure that the weld process is working properly and can be implemented trouble-free in your production. This begins with the determination of the process parameters and goes beyond the construction of the weld tools and equipment to complete integration solutions into existing machines/production lines.
The ultrasonic generator converts the supply voltage (50 Hz and 230V) into a high frequency voltage of 20, 30, or 35 kHz which is converted into mechanical vibrations in the converter. The wave increases itself on its way from converter through the booster to the sonotrode. The sonotrode is the actual weld tool, transferring the vibrations into the component.
The amplitude is the movement of the weld tool, and more specifically, the deflection at which the stack expands and contracts – between 5 and 50 µm. As comparison: The diameter of a human hair is only 100 µm. The frequency is the number of oscillations per second. With ultrasonic welding, frequencies between 20 and 35 kHz are used. 35 kHz equal 35.000 movements per second.