An ultrasonic welding system is provided. The ultrasonic welding system includes a support structure for supporting a workpiece. The ultrasonic welding system also includes a weld head assembly including an ultrasonic converter carrying a sonotrode. The ultrasonic welding system also includes a z-axis motion system carrying the weld head assembly. The z-axis motion system includes (i) a z-axis forcer for moving the weld head assembly along a z-axis of the ultrasonic welding system, and (ii) a z-axis overtravel mechanism disposed between the z-axis forcer and the weld head assembly.