A system for use in ultrasonic additive manufacturing processes, comprising a milling machine or the like and a weld assembly. The milling machine further includes a spindle adapted to receive a milling tool, wherein the spindle is capable of moving in the z-axis direction; and a table positioned beneath the spindle, wherein the table is capable of moving in the x-axis direction and the y-axis direction. The weld assembly is adapted to be mounted on the spindle of the milling machine and further includes an ultrasonic weld head; a tapered tool shank adapted to connect the weld assembly to the spindle; and a unique mating collar disposed between the ultrasonic weld head and the spindle, wherein the mating collar is operative transfer thrust loads associated with ultrasonic additive manufacturing processes from the ultrasonic weld head to the z-axis of the spindle without damaging the spindle or other components of the machine.