A Twist in Ultrasonic Metal Welding

Ultrasonic-based processes and electric vehicles have much in common: Efficiency, performance capability, reliability, connectivity, and eco-friendliness are among the essential characteristics that they both possess. The torsional ultrasonic welding procedure called SONIQTWIST® was developed by Telsonic AG in 2006 and quickly established itself as the joining procedure for a great variety of plastics and metals. Torsional energy is gently exerted to the area of the joint, thus suitable even for highly sensitive parts. On the other hand, even very strong forces may be applied in a very short time which is critical, for example, for joining aluminum or copper foils. Even painted plastic parts can be joined firmly and safely without leaving visible indentations.  The Telsonic innovative Torsional welding technique has created  breakthroughs applications that were impossible or not acceptable up to last decade. Now the technology  is increasingly specified by carmakers for use in EV for weight control, battery packaging, cable to terminal connections, bus bars, battery manufacturing and power electronics. 

Torsional Welder TSP for both Plastic & Metal

Telsonic Torsional SONIQTWIST provides the maximum movement (amplitude) in the  outer edge .    Torsional technology allow welding of larger size welds, more geometrical shapes, out of reach joining areas , and where gentle vibration is required . This has expanded the ultrasonic application spectrum significantly.  Many joining applications that were impossible by conventional longitudinal welding are now possible.  In fact, the Torsional welding is sometimes found to be the only solution for electric car battery manufacturers and in the termination of high-voltage cables. Other examples where torsional ultrasonic welding proves to be the superior method are bus bars, 3D terminals and integrated gate bipolar transistors (IGBT).  In plastic welding , Torsional process allows joining plastic parts with fine contours and openings, such as nozzles, valves or connectors, without damaging the parts themselves as well as  attaching plastic brackets to the inside of painted bumpers for holding distance sensors.   Since the closing movement of the welding system only takes place in the Z axis, the system is very easily accessible and enables short cycle times.

Benefits of SONIQTWIST® Welding

  • Very low vibration stress in the lower part. Only 1/10 of stress induced compared with                                        

conventional ultrasonic weld procedures (ideal for sensitive parts, electronics)

  • Very short welding time (often < 1 second)
    • Good accessibility as only one vertical movement is required
    • Very high weld strength can be achieved
    • Comprehensive control options of process
    • Far zone welds in centimeter range
    • No membrane effects in foils, tissues and thin parts (no energy concentration in centre of

foil and no hole effect)

  • Great welding depth possible
    • Rectangular shapes can also be welded securely. Parts do not have to be round in shape.
    • A power of up to 14,400 Watts possible
    • Foreign bodies in the welding seam do not impair process

      SONIQTWIST welding technology application overview for metal components

1. Ultrasonic welding pole – The application requires the welding to take place at the bottom of the cylindrical cell through the jelly roll, so the ultrasonic welding tool has to have a long reach.

2.  Connection bolt on current conductor – This is a 360°weld around the bolt that requires a recess on the ultrasonic tool. Connecting the bolt on the connector conductor allowed significant manufacturing cost reduction.

3. Cu washers welded to Al busbars to prevent corrosion.

4. Battery cap welding – The space is limited as the film-style electrical conductor must be welded into an embossed channel in the battery cap.

5. Stud welding on connectors or busbar is possible.

6. Electrical connection on IGBT – The Cu-plated ceramic printed assembly board in IGBT modules for welding the conductor. The gentle vibration allows more consistent welds without damaging the ceramics. The process is also very forgiving on the fine wire bonds on the DBC.

As product designers and process engineers continue to familiarize themselves with the torsional welding process and its capabilities, the technology is positioned to help propel the EV industry to even greater heights.   We will certainly learn more in time and innovative ideas will be introduced, but ultrasonic welding will no doubt be a part of the solutions to achieve the objectives in material cost, weight and space reduction, and less labor-intensive manufacturing processes.