VIEW ISO 9000 CERTIFICATE

THE TECHNIQUE OF ULTRASONIC METAL WELDING

When joining metallic or ceramic materials using ultrasonics, the energy needed for welding is applied in the form of mechanical vibrations imposed on the materials. The welding tool (the sonotrode) is connected to the part of the joint turned towards it , which causes it to vibrate in the longitudinal direction. The other part of the joint does not move, as this is secured to a fixed anvil element. In order for a relative vibration movement to be incurred between the parts which are to be welded, the connecting surfaces of the sonotrode and the anvil must feature a specific structure.

An ultrasonic generator converts the 50 Hz mains current into a high frequency AC current with an operating frequency of 20-70 kHz. The power requirement depends on the application and can be between 500 and 10'000 W. The electrical vibrations are changed in the converter unit into mechanical vibrations of the same frequency, transferred via the booster (the transformer unit) and the sonotrode onto the material which is to be welded. A control unit controls and monitors the welding process and also allows for the electronic assesment of the relevant welding parameters.

In metallurgical terms, ultrasonic metal welding is classed as a cold welding process. Because of intense friction at the welding points the oxide skin is broken open and the two parts pressed together, while at the same time pressure is exerted. These processes trigger the action of atomic binding forces. The relatively small temperature increase is far below the melting temperature and makes little contribution to the bonding. As there are no structural changes to the base material, this process does not suffer from the adverse effects that such changes can bring.

Welding || Metal welding || Advantages || Applications || Continous Welding
Linear ultrasonic welding || Torsional welding || Ring welding