Ultrasonic welders are formed by two main parts: an electric part (generator) and an acoustic part (vibrating set). Both of them have to work in perfect tuning. The generator creates a series of pulses that are regular and perfect, while the acoustic part transforms them into vibrations. The tool that is welding (which will be called sonotrode) vibrates at a frequency that equals the frequency being emitted by the generator. The sonotrode is in charge of transmitting this extremely rapid and intense vibration to the plastic item, which will start melting. Furthermore, it is important to realize that the sonotrode will keep cold during welding, as it just transmits a vibration and not heat; this way, plastics will not lose their own technical features and the item will not get deformed.