For joining complex injection molded thermoplastic parts, ultrasonic welding machine can be easily customized to fit the exact specifications of the parts being welded. The parts are sandwiched between a fixed shaped nest and a sonotrode (horn) connected to a transducer, and a ~20 kHz low-amplitude acoustic vibration is emitted.. When welding plastics, the interface of the two parts is specially designed to concentrate the melting process. One of the materials usually has a spiked energy director which contacts the second plastic part. The ultrasonic energy melts the point contact between the parts, creating a joint. This process is a good automated alternative to glue, screws or snap-fit designs. It is typically used with small parts such as cell phones, consumer electronics, disposable medical tools, toys, etc., but it can be used on parts as large as a small automotive instrument cluster.
Ultrasonic welding can be used for both hard and soft plastics, such as semicrystalline plastics, and metals. Ultrasonic welding machine also has much more power now. The understanding of ultrasonic welding has increased with research and testing. The invention of more sophisticated and inexpensive equipment and increased demand for plastic and electronic components has led to a growing knowledge of the fundamental process. Scientists from the Institute of Materials Science and Engineering (WKK) of University of Kaiserslautern, with the support from the German Research Foundation, have succeeded in proving that using ultrasonic welding processes can lead to highly durable bonds between light metals and Carbon-fiber-reinforced polymer (CFRP) sheets.