Herrmann Ultrasonics Sealing Ultrasonic welding of films Film welding is important for the packaging industry, for instance. Here, fine films can be welded with each other or with other materials. This is how coffee capsules, drinks packaging and much more are made. The special feature in the ultrasonic welding of films: The heat is generated within the material and not applied from outside. This means that the required temperature is not too high and the film is not damaged. Film shrinkage is prevented.