Ultrasonic metal welding (USMW) is a welding technique often used in the electronic and automobile industries. However, the strength of the welds it produces is influenced by a large number of variables, making USMW difficult to monitor. There is therefore a need for monitoring parameters which can be used across a large number of influencing variables, and features which can help estimate the weld strength. The goal of this work is to investigate the usability of the horn and anvil vibrations at the welding frequency as such monitoring parameters, and whether features that strongly correlate with the weld strength can be derived from them.
In this study, the horn and anvil vibrations were tracked during welding of 120 welds using laser vibrometers. For each weld, the horn and anvil envelopes are compared to the weld strength and to the literature to identify welding stages. The results showed that the strength of a weld plateaus when it reaches its stage of maximum strength, and that this stage can be identified by both the horn and anvil vibrations. Then, features are extracted from the envelopes and used to estimate the strength of different welds.
Elie Abi Raad is currently a doctoral candidate at the Institute for Hearing Technology and Acoustics, RWTH Aachen, Germany. He previously completed a BE in Mechanical Engineering in 2015 at the American University of Beirut, Lebanon, and a MA in Mechanical Engineering with a specialization in Acoustics in 2017 at the Paris-Saclay University, France. His current research focuses on the use of structure borne and airborne vibrations to monitor and characterize Ultrasonic Metal Welding.