Generally speaking, in respect to the ultrasonic frequency, for hardware, mechanics, automobile and motorcycle as well as compressor industries, the cleaning is mostly realized by cleaners with 28KHZ frequency. For cleaning optics and photoelectron device and circuit boards, the frequency of 40KHZ will be applied, high-frequency ultrasonic cleaners are suitable for the refined cleaning of computers and microelectronic elements, megahertz ultrasonic cleaning is suitable for integrated circuit chips, silicon wafer and wave thin films, which can remove the dirt of micron and submicron level and don’t damage the cleaning components. As for the selection of ultrasonic power, if the ultrasonic power is too high, at this moment, the cavitation strength in fluid is increased significantly, the relatively refined components will produce corrosion points, and the water point corrosion will be enlarged, if the vibration panel has suffered from cavitation corrosion, there will be severe cavitation corrosion for water bottom under strong power, lowering the equipment life, resulting in unnecessary damages. But if the ultrasonic cleaning power is set lower, much time will be consumer for removing the dirt, this is also not recommended.
In general condition, when the sound intensity increases, the ratio of the largest radius of cavitation bubble to original radius will increase, the cavitation intensity increases, then the higher the sound intensity will be, and the stronger the cavitation will be, which is beneficial for the ultrasonic cleaning function. However, it doesn’t mean that it is better for possessing higher ultrasonic power, for higher sound intensity, it will produce a large amount of useless bubbles, increasing the scattering attenuation, forming sound barrier, in the meantime, the increased sound intensity will promote the nonlinear attenuation, the cleaning effect for place far away from the sound source will be reduced. Therefore, the cleaning effect of ultrasonic is not directly proportional to the set power and working time, sometimes, the dirt can not be removed for utilizing the low power for a long time, if the power reaches certain value, then it is possible that the dirt can be eliminated immediately. If the ultrasonic power is too high, at this moment, the cavitation intensity in liquid will be increased significantly, the relatively refined components will produce corrosion points, the water point corrosion will also be enlarged, if the vibration panel surface has suffered from the cavitation corrosion, there will be severe cavitation corrosion for water bottom under strong power, the device life can be reduced, resulting in unnecessary damages, in the meantime, there will be severe cavitation for the vibration panel at the bottom of cleaning tank, the tank life can be narrowed.
First. The Ultrasonic Cavitation Threshold Value is in Close Relation with the Ultrasonic Frequency
The ultrasonic cavitation threshold value is in close relation with the ultrasonic frequency. The higher the frequency is, the bigger the cavitation threshold value will be. If the frequency is low, the cavitation threshold value will also be low, at this moment, there will be the cavitation effect easily. Besides, in low frequency condition, the time interval for fluid being compressed and diluted will be longer, allowing the bubble to grow into larger size, increasing cavitation intensity, which is conducive for ultrasonic cleaning
Therefore, low-frequency ultrasonic cleaners are suitable for larger components and cleaning workpiece with higher degree of adhesion for surface, such as the automobile valves and so on. But the low-frequency ultrasonic cleaners are easy to corrode the cleaning object surface, their frequency is relatively low, and producing relatively larger noises. Hence, the relatively low-frequency is not suitable for components with higher workpiece surface requirements and insufficient hardness.
The ultrasonic cleaners with higher frequency usually possess higher penetration capability, with the same sound intensity, they will produce more cavitation bubble amount than the low-frequency ones, therefore, they are suitable for cleaning the relatively refined components with complex surface structure and blind holes. Besides, the noise for high-frequency ultrasonic cleaners are relatively low, with relatively lower cavitation intensity, which are suitable for some refined components and the conditions where the degree of cohesion for workpiece surface is poor.
Second. What Matters Most is the Suitable Power
When the ultrasonic cleaner power becomes higher, the sound power will also be bigger, and the cavitation intensity will be stronger. Though it is helpful for the cleaning effect, the cavitation corrosion towards trough bottom is also more severe, at last, resulting in the shorter life for cleaners; However, if the cleaning power for ultrasonic is relatively lower, it will affect the cleaning time of objects, leading to the relatively longer cleaning time or poor cleaning effect.
Whether the power for ultrasonic cleaners are selected right or not, it plays a pivotal role for the cleaning effect and time of ultrasonic cleaners. The cleaning effect can be the best only with reasonable and suitable ultrasonic power.
