An ultrasonic stir welding device provides a method and apparatus for
elevating the temperature of a work piece utilizing at least one
ultrasonic heater. Instead of relying on a rotating shoulder to provide
heat to a workpiece an ultrasonic heater is utilized to provide
ultrasonic energy to the workpiece. A rotating pin driven by a motor
assembly performs the weld on the workpiece. A handheld version can be
constructed as well as a fixedly mounted embodiment.