The torsional process is advantageous in that only a small part of the vibrations is transferred into the area surrounding the weld seam. On the one hand this is gentler on any delicate components and surfaces and on the other hand this achieves greater energy density in the area of the weld.
Usually, the welding system is arranged vertically. However, the torsional welding system is a high-frequency friction welding process. The vibrations are transferred tangentially; the sonotrode activates the upper part and moves it horizontally in relation to the lower part. The high vibration frequency of 20 kHz, the amplitude and the welding pressure create a melt between the parts to be joined.
The torsional movement of the sonotrode generated by the ultrasound has practically no impact on the area surrounding the weld area. For this reason, the torsional process is particularly suitable for delicate applications where vibrations outside the weld zone could cause damage. Examples are foils, fabrics, thin injection moulded parts (parts with springs attached, grilles with thin webs), ceramic and electronic components. In some cases it is also possible to join different types of plastic.
The torsional process is suitable for welding plastics and metals. The accessibility of the system is very good and enables short cycle times, because the feed movement of the welding system is restricted to the Z axis.