The cleaning ability of the ultrasonic cleaning machine directly depends on the ultrasonic frequency, so it is best to calculate the ultrasonic frequency of the equipment in advance, but because the speed is different in different media, this brings difficulties to the calculation.

After repeated measurements, it was found that there are two main propagation forms of sound waves in solids, namely longitudinal waves and transverse waves, and the wave speeds of these two waves are also different. For example, in stainless steel, the longitudinal wave velocity is 5790 m/s and the shear wave velocity is 3100 m/s. Due to the poor sound transmission performance of polyethylene plastic, the longitudinal wave speed of sound waves in polyethylene rods is only 920 m/s, which is not as fast as the speed of sound in water.

The ultrasonic cleaning machine uses the indirect and direct effects of cavitation, deceleration and direct flow in the sonic liquid on the liquid and dirt, so that the dirt layer is dispersed, emulsified, and peeled off to achieve the purpose of cleaning. In the currently used ultrasonic cleaners, cavitation and direct inflow are used more.