Ultrasonic Welding uses high-frequency ultrasonic acoustic vibrations which are applied to materials that are being held together under pressure to create a solid-state weld. This method is most commonly used to join thermoplastics and in joining materials that aren’t similar and does not require any bolts, nails, soldering material or adhesives that are needed to join the materials together.
Although ultrasonic welding uses vibration to create a weld, ultrasonic welding is a different method from “vibration welding” (also known as friction welding). In ultrasonic welding, both materials are held in place and a high frequency noise is applied to produce friction and then create a weld.
During the welding process, the materials to be welded are placed between a fixed shaped nest and a sonotrode which is connected to a transducer which produces a low amplitude acoustic vibration. The acoustic energy creates friction, produces heat, and then the parts are welded together in less than a second—making it one of the fastest welding methods in use today.
While vibration welding has the capacity for larger components, ultrasonic welding offers a far less complex process and presents less limitations for which materials can be joined together. These advantages for ultrasonic welding generally apply when it’s compared to other plastic welding processes such as adhesive welding, spin bonding, and hot plate welding. Having said that, ultrasonic welding has its limitations when joining together certain materials (see this chart).
Advantages of Ultrasonic Welding
Because ultrasonic welding requires no connective bolts or soldering materials to bind the two pieces together it saves on manufacturing and production costs. The welds created using this process are visually appealing since there are no visible seams which can detract from the finished piece. The process of ultrasonic welding is primarily an automated process that only requires the welder to pull a lever or push a button to produce the ultrasonic weld.
Since ultrasonic welding can be used to join wires and circuitry, it is perfect for use in industries that produce computer and electrical components. It is ideal because it creates reliable bonds without introducing any impurities or thermal distortion to the components being joined. The weld also dries rapidly because there are no adhesives or solvents to dry and, there is no need for the materials to cure.