Ultrasonic welding is the process of converting electric current into electric energy through ultrasonic generator.The converted high-frequency electric energy then converted into the mechanical motion of the same frequency again through the transducer, and the mechanical movement is transmitted to the welding head through a set of horn device which can change the amplitude. The vibration energy received by the welding head is transferred to the joint of the work piece to be welded. In this area, the vibration energy is converted into heat energy by friction, and the plastic is melted. Ultrasonic can be used not only to weld hard thermoplastic plastics, but also to process fabrics and films. Heat energy comes from the reciprocating movement of a work piece on another surface with a certain displacement or amplitude under a certain pressure. Once the expected welding degree is reached, the vibration will stop, and at the same time, there will still be a certain pressure applied to the two work pieces to cool and solidify the just welded parts, thus forming a close combination.