Ultrasonic welding involves the use of high frequency mechanical sound energy to soften or melt the thermoplastic at the joint line. Parts to be joined are held together under pressure and are then subjected to ultrasonic vibrations usually at a frequency of 20 or 40kHz. The ability to weld a component successfully is governed by the design of the equipment, the mechanical properties of the material to be welded and the design of the components. Ultrasonic welding is a fast process (weld times are typically less than one second), can easily be automated and can produce hermetic seals. It is therefore ideally suited to welding components in mass production.