What is ultrasonic wave: wave can be divided into three kinds, namely infrasound, sound wave, ultrasonic wave. Infrasound frequency is below 20Hz; sound frequency is 20Hz ~ 20kHz; ultrasonic frequency is above 20kHz. The infrasound and the ultrasonic wave are inaudible to the human ear. Because of its high frequency and short wavelength, the ultrasonic wave has good directivity and strong penetration, which is why the ultrasonic cleaning machine is designed and made.       

                                                                                                  

                                                                                       
The sound you normally hear is a 20-20,000 hertz sound wave. The sound waves above 20,000 hertz are called ultrasonic waves. The sound waves travel in a longitudinal direction along a sinusoidal curve, when a weak acoustic signal is applied to a liquid, it produces a certain negative pressure on the liquid, that is, the volume of the liquid increases, the molecular gap in the liquid increases, and many tiny bubbles are formed, when a strong acoustic signal is applied to a liquid, it produces a positive pressure on the liquid, i. e. the volume of the liquid is compressed and reduced, and the tiny bubbles formed in the liquid are crushed. Studies have shown that when Sonication in a liquid, the bursting of each bubble in the liquid creates an extremely powerful shock wave equivalent to hundreds of Baidu temperatures and thonds of atmospheres at once, this phenomenon is called"Cavitation", ultrasonic cleaning is the bubble in the liquid produced by the burst of shock wave to achieve the cleaning and washing of the workpiece inside and outside the role of the surface.
The sub-ultrasonic wave propagates in the liquid, causing the liquid and the cleaning tank to vibrate together at the ultrasonic frequency, and the liquid and the cleaning tank vibrate at their own natural frequency, which is the acoustic frequency, so people hear the hum.