Ultrasonic welding

Ultrasonic welding welds metal using ultrasonic vibrations as the energy source. This type of welding can be used for both metals and non-metallic materials. It is used in seam, spot, and contour welding. In this case, bending and longitudinal mechanical vibrations are used. Ultrasonic welding welds metal using ultrasonic vibrations with a frequency of 20-60 kHz. These vibrations are generated by applying current from an ultrasonic generator to the winding of a magnetostrictive transducer, which is assembled from thin 0.1-0.2 mm plates. The material of these plates allows for changes in geometric dimensions when exposed to an alternating magnetic field. Directing the magnetic field along the plate stack facilitates the shortening or lengthening of the magnetostrictor, converting high-frequency electrical vibrations into mechanical vibrations.

Ultrasonic welding method

The ultrasonic welding method includes the following:

• the parts to be welded are fastened together under pressure;
• are subjected to high-frequency oscillation, vibration occurs, which causes tension at the connection point;
• as a result of such a docking, heat is generated on the surface due to friction, the force of the vibration vector to the surface is directed at a right angle;
• High-frequency electrical energy is converted into vertical mechanical movement.

High-frequency vibrations occur during dry friction of particles in the surfaces being welded, which destroys surface oxide films. After this, pure friction begins, which is stronger, and friction points form. Grains begin to form between the two metal surfaces, creating a common boundary.

The ultrasonic welding method is performed:

• by relief;
• overlapping;
• by joining a flat element with a round one;
• by crushing the edges;
• multilayer parts and films.

The oscillation amplitude and mechanical oscillation system are crucial technological parameters of a welding system, as they transmit ultrasonic energy to the workpiece. For effective operation, an amplitude of 30-70 µm is required.

Ultrasonic metal welding

Ultrasonic metal welding is a type of true welding. Metal crystals are brought together to within atomic distances, creating a powerful attraction and a strong weld joint without heating the metal to its melting point. This welding process requires no solder, no connecting wires, and no subsequent surface cleaning. It is an environmentally friendly method of joining metals.

Advantages of ultrasonic metal welding:

• there is no need to clean the surface to be welded, only from grease;
• limited, localized heating;
• accessible in difficult places;
• no harmful emissions;
• fractions of a second from heating to welding;
• Very thin sheets up to 0.001 mm are welded.

Disadvantages of this type of welding:

• the thickness range is very limited;
• high cost of ultrasound generators;
• additional external compression.