For 3-D shapes such as the daytime running light, the ultrasonic Sonotrode is separated in two elements: a Composite Sonotrode with individually fixed single Sonotrodes, referred to as screw-in studs; every individual stud represents a small vibrating Sonotrode. The studs with different heights adjust exactly to the part and each stud has to be designed and manufactured as a stand-alone sonotrode. In order to guarantee correct vibration, the Composite Sonotrode is calculated by means of the Finite-Element-Method (FEM) and gauged for frequency, idling power and amplitude. Every individual stud must also be gauged for frequency. This is where the know-how of the ultrasonics specialist Herrmann Ultrasonics comes in, for the studs are designed in various lengths and for different interfering contours, i.e. for leaving a cutout for lettering on a component. This has an influence on the vibrating behavior.
In order for the single Sonotrodes (studs) to vibrate correctly, they are individually mounted and adjusted in a difficult manual process. This requires experience and a lot of skills. Under load simulation, the completed Sonotrode is laser-gauged and the required corrections are performed by machining processes. Software which was specifically developed for this purpose, measures up to 100 measuring points to create the amplitude profile. If necessary, tension corrections will be made. However, the right frequency, no load power and amplitude have to be reached.