Ultrasonic welding (UW) technology is an ultra-fast joining process for joining thermoplastic composite structures that provides excellent joint strength. There are two types of ultrasonic welding: ultrasonic plastic welding and ultrasonic metal welding. Ultrasonic plastic welding uses heat generated by high-frequency mechanical motion to join or modify thermoplastics. It is accomplished by converting high frequency electrical energy into high frequency mechanical motion. Ultrasonic metal welding is defined as a solid-state welding process that uses a high-frequency vibrator (frequency of >20,000 Hz) to generate heat and pressure to join metals. No filler material or filler bars are used in the ultrasonic welding of metals.