What is flash in ultrasonic welding?

In ultrasonic welding, flash refers to the excess material that may be squeezed out of the weld area during the welding process. This excess material can be seen as a thin film or layer around the welded part. Flash can be caused by a variety of factors, including excessive amplitude, high welding force, or poor material control. Flash is typically undesirable as it can impact the strength and appearance of the weld. Therefore, it is important to optimize the welding process to minimize the amount of flash produced.