The process uses low amplitude, high frequency (ultrasonic) vibrational
energy. One of the two parts to be joined is fixed firmly within a stationary
holding jig, while the mating part is subjected to a sinusoidal ultrasonic
vibration normal to the contact area. As a result of the friction between the
parts and internal friction in the parts, heat is generated. This causes the
polymer to melt at the interface. When vibration stops, the weld cools down
and solidifies.
Ultrasonic welding has the advantage that the melted polymer is not exposed to
air, which can be important for materials that are susceptible to degradation
or oxidation. The product is exposed to vibrations during welding, which can
be a disadvantage for certain applications.
