The advantages of ultrasonic cleaning machine are: good cleaning effect and simple operation. The sound that people hear is a sound wave signal with a frequency of 20-20000Hz. The sound wave with a frequency higher than 20000Hz is called ultrasonic wave. The transmission of the sound wave is longitudinal in accordance with the sine curve, producing a large number of small bubbles. One reason is that tensile stress occurs locally in the liquid to form negative pressure, and the reduction of pressure makes the gas dissolved in the liquid supersaturated, and escapes from the liquid to become small bubbles; Another reason is that the strong tensile stress "tears" the liquid into a cavity, which is called cavitation.