These vibrations are then transmitted to the parts being welded through the booster and horn. A booster amplifies the mechanical vibrations being transmitted to the parts being welded. The ratio of amplification depends on the choice of booster. Choice of booster depends on the material, joint design and horn design. The horn is the tool that physically vibrates on the plastic part and causes the weld.
Horns come in a variety of shapes and sizes.
Typically, each specific weld requires a specific horn to transmit the ultrasonic energy to the weld point efficiently. Heat staking is a welding process that reforms a plastic stud so it will hold a part in place. Spot welding is used for tagging together plastics, generally sheets, for holding them together. Welding tips are available to improve aesthetics of a spot weld. Unlike glues and adhesives, ultrasonic welding is environmentally safe.