Principle: Sound waves propagate longitudinally according to a sinusoidal curve, that is, one layer is strong and the other layer is weak, and then they propagate in turn. When the weak acoustic signal acts on the liquid, it will produce a certain negative pressure on the liquid, that is, the liquid volume increases, the molecular gap in the liquid increases, and many tiny bubbles are formed. When the strong acoustic signal acts on the liquid, it will produce a certain positive pressure on the liquid, that is, the volume of the liquid is compressed and the tiny bubbles formed in the liquid are crushed. Studies have proved that when ultrasonic waves act in liquid, the rupture of each bubble in liquid will produce a shock wave with huge energy, which is equivalent to a high temperature of several hundred degrees and up to several thousand atmospheres in an instant. This phenomenon is called "cavitation", and ultrasonic cleaning is to clean and scour the inner and outer surfaces of the workpiece by using the shock wave generated by the bursting of bubbles in liquid.
The cause of buzzing: ultrasonic wave propagates in the liquid, which makes the liquid vibrate with the cleaning tank at ultrasonic frequency. When the liquid vibrates with the cleaning tank, it has its own natural frequency, that is, the frequency of sound waves, so people hear buzzing.
Supplement: The sound people hear is an acoustic signal with a frequency of 20-20000Hz, and the acoustic wave above 20000Hz is called ultrasonic wave.