The reason is that when liquid flows across the surface of the workpiece, it forms a viscous film. At low frequencies, viscous films are usually thick and contain small particles. No matter how high the ultrasonic power (intensity), the cavitation bubble can not contact the small particles, and therefore can not remove the small particles; and when the ultrasonic frequency increases, the thickness of the adhesive film will decrease, and ultrasonic cavitation bubbles can come into contact with small particles and strip them from the surface of the workpiece. Therefore, low-frequency ultrasound removal of large particles of impurities is very good, but the removal of small particles of impurities is very poor. In contrast, high-frequency ultrasound is particularly effective in removing small particulate impurities.
Generally speaking, the 28KHZ frequency of the cleaning machine is used for cleaning hardware, machinery, auto, compressor, and other industries. Optical photoelectric cleaning, circuit board cleaning, and other use of 40KHZ frequency. High-frequency ultrasonic cleaning machine for computers, micro-electronic components of the fine cleaning. Megahertz ultrasonic cleaning for IC chips, silicon chips, and wave plate cleaning, can remove micron, and sub-micron scale dirt and will not cause any damage to cleaning parts. For some cleaning applications (such as LCD, semiconductors, etc.), the use of traditional frequency not only can not meet the cleaning requirements, and may cause damage to the workpiece.
