Ultrasonic welding is a solid-state joining process that uses high-frequency ultrasonic acoustic vibrations, applied locally to workpieces that are held together under pressure.
Used for both plastics and metal welding, this technique is able to join dissimilar materials.
When applied to metals the temperature stays below the melting point of the materials, which means the properties of the metals are not changed as can be the case with higher-temperature joining methods.
Ultrasonic welding removes the need for connecting bolts, nails, adhesives, or soldering materials, making it popular for a range of applications from automotive and aerospace to medical and computing.
Early ultrasonic welding was only able to join rigid plastics and it was first applied to the toy industry. However, the first car to be made entirely from plastic was assembled with ultrasonic plastic welding in 1969. The automotive industry dropped the idea of an all-plastic car, but kept using ultrasonic welding as the technology was also taken up by other industries.