Ultrasound plastic welding technology is a fusion welding technology. The principle of this technology is to convert friction and vibration energy into heat. The high-frequency vibration generated by the ultrasonic system is transmitted to the parts to be jointed through the welding die under the action of pressure, which will lead to the relative vibration in the jointing area. Friction heat can cause micro-melting, which hinders vibration, absorbs vibration energy and converts it into heat, and ultimately causes welding contour to melt in a very short time, thus forming macromolecule compounds. Usually, the welding contour of the plastic parts to be welded must meet the requirements of the corresponding material type and joint.

The heat required for ultrasonic sealing is only generated in the thermoplastic sealing layer. The contour can concentrate on importing energy, so the sealing time is very short. When sealed by ultrasonic wave, heat is generated inside the film. Therefore, there is no need to supply heat from outside. The mould is kept at low temperature in welding process. The heat generated in the product is extremely low. The temperature balance between the carrier layer and the sealing layer is quickly carried out. This results in excellent hot fusion strength.