This presentation discusses the advantages and limitations of using Dynamic Time Warping (DTW) to quantify the similarity between measurements of different weldings. In this project, machine vibrations and airborne sound occurring during Ultrasonic sheet Metal Welding are recorded, using two laser Doppler vibrometers and a microphone. The goal of the project is to get a better understanding of the processes that occur during this type of welding and, ultimately, to get better inline quality control.