A method and apparatus for joining multiple layers of materials using an ultrasonic welding apparatus. The ultrasonic welding apparatus utilizes a sonotrode to perform a weld between at least the top and intermediate layer of the multi-layer member. Then, either the multi-layer member or the ultrasonic welding apparatus is rotated such that the bottom layer is positioned adjacent the sonotrode wherein the sonotrode forms a weld between at least the bottom layer and intermediate layer of the multi-layer member. The apparatus includes an ultrasonic welding gun having a C-shape frame including a base portion and a head portion. An ultrasonic welding device, including a sonotrode, is secured to the head portion and an anvil secured to the base portion. The ultrasonic welding gun is connected to a robot operative to position the ultrasonic welding gun to perform the welding operation.