Development of Finishing System Using Acoustically Levitated Abrasive

Based on the acoustic levitation phenomenon, we propose and develop an acoustic levitation / positioning system to control the movements of free abrasives to finish inner surfaces. Described in this paper are the theoretical analysis of levitation forces generated in a standing wave field and the results of experiments involving levitation and positioning. We first calculate the wave amplitude and frequency required to levitate the abrasives. Based on the results, we develop a system consisting of a sound transducer (speaker), a reflector (an aluminum plate), an amplifier, and a function generator, and we successfully not only levitate but also position actual abrasives in a tube. We find that the relation between the size and density of the abrasives and the strength of the acoustic field (wave amplitude and frequency) basically agree with the theoretical prediction. In addition, the kinetics of levitated abrasives, including their positions and movements, are precisely controlled by varying the wave frequency and switching from one node position to another.