Ultrasonic welding horns are specially tuned devices used to deliver ultrasonic energy to the plastic part being welded. They are tuned to match the welding system to which they are attached, usually to within ±30Hz of the machine's frequency.
Selection of the horn material (e.g. aluminium, titanium or tool-steel), the length and shape of the horn and profile of the tip are all fundamental to producing the correct longitudinal wave response in the horn.
Maximum size of the welding horn will depend on the material being welded. For example, with a material that requires low power for welding, such as polystyrene, the maximum horn size will be approximately 250mm (width/breadth ordiameter). For materials that are more difficult to weld, the maximum size will be approximately 90mm (width/breadth or diameter).
Manufacture of ultrasonic welding horns should be left to the ultrasonic welding equipment manufacturer who will design the horn to match both the frequency of their equipment and the profile of the component being welded.
See further information on polymer welding.