The advantages of ultrasonic cleaning machine are: good ultrasonic cleaning effect, simple operation. The sound that people hear is the sound wave signal with the frequency of 20-20000 Hz. The sound wave with the frequency higher than 20000 Hz is called the ultrasonic wave. The transmission of the sound wave propagates longitudinally according to the sine curve, producing a large number of small bubbles. One reason is that the local tensile stress in the liquid forms a negative pressure, and the decrease of the pressure makes the gas originally dissolved in the liquid supersaturated, and then escapes from the liquid, becoming a small bubble; the other reason is that the strong tensile stress "tears" the liquid into a cavity, which is called cavitation.