Ultrasonic Horn Vibration


An “ultrasonic horn” is the device which concentrates this energy and applies it to a process. They come in many different sizes and configurations depending on the task for which they are designed. As the tip of the horn (or contraction area) is brought in contact with a part at a certain pressure, frictional heat is generated causing the material to plasticize locally, creating an insoluble connection between two parts within a very short period of time.

As the energy is removed, the part will cure, creating the bond. It is important for the operator to precisely control the motion characteristics of the horn in order to maintain product consistency and integrity. Periodic measurements of horn frequency and amplitude are therefore required. For this measurement MTI Instruments offers a unique non-contact fiber optic vibration sensor, the MTI-2100 Fotonic Sensor. It features advanced fiber optic and electronic technologies for precise measurements of displacement, position and vibration.

Being non-contact, it does not affect or influence the target motion or dampen the vibration amplitude. A fiber optic probe contains a set of light transmit and light receive fibers, available in several different configurations. The light intensity is monitored, which is proportional to the distance between the probe tip and the target being measured. The LCD display provides peak to peak amplitude measurements of the horn in both English and metric units while and a rear panel BNC connector provides “real-time” output waveform data. This waveform can be analyzed to determine frequency, amplitude and consistency of the horn output, which is helpful in analyzing new horn designs as well as detecting horn defects. A general purpose probe module, such as the MTI-2062R, offers a frequency response of 150 kHz, a small target footprint of 1.2 mm and an output resolution of 2.5 nano-meters. For horn applications where the tip is thin or tapered MTII offers a unique “Edge” probe. It creates a “curtain” of light that is projected onto the horn tip.

As vibration occurs, the amount of light received modulates and the MTI-2100 converts this modulation to a peak-to-peak displacement.