Other factors affecting the ultrasonic cleaning effect
The acoustic characteristics of the items to be cleaned and their arrangement in the cleaning tank also have a significant impact on the cleaning effect. Cleaning objects with high sound absorption, such as rubber and fabric, have poor cleaning effects, while cleaning items with strong sound reflection, such as metal parts and glass products, have good cleaning effects. The smaller side of the cleaning parts should face the sound source and be arranged at a certain distance. The items to be cleaned must not be placed directly at the bottom of the cleaning tank. Especially for heavier cleaning parts, it is necessary to avoid the vibration of the bottom plate of the groove and also to prevent the cleaning parts from scratching the bottom plate and accelerating cavitation corrosion. It is best to hang the cleaned items in a tank or hold them in a metal basket and hang them. But it should be noted that it should be made of metal wire. And as much as possible, use fine wires to make baskets with larger gaps to reduce sound absorption and shielding.
The flow rate of the cleaning solution also has a significant impact on the ultrasonic cleaning effect. It is best for the liquid to remain stationary during the cleaning process, as this allows the growth and closure of bubbles to be fully completed. If the flow rate of the cleaning solution is too fast, some cavitation nuclei will be carried away by the flowing liquid, while others will leave the sound field before reaching the entire process of growth and closure movement, thus reducing the overall cavitation intensity. In the actual cleaning process, sometimes to prevent dirt from re-adhering to the cleaned items. The cleaning solution needs to be constantly updated. At this time, it should be noted that the flow speed of the cleaning solution should not be too fast to avoid reducing the cleaning effect.
The content of gas in the cleaning solution also has an impact on the ultrasonic cleaning effect. If there is residual gas (non-cavitation nucleus) in the cleaning solution, it will increase the loss of sound propagation. In addition, the gas that diffuses into the cavitation bubble during its movement will reduce the intensity of the shock wave when the cavitation bubble collapses, thereby weakening the cleaning effect. Therefore, some ultrasonic cleaning equipment has the function of degassing. When starting up, it first performs vibration at a power level lower than the cavitation threshold, and degassing is carried out through pulse or intermittent vibration. Then increase the power to the normal cleaning power level for ultrasonic cleaning.
The influence of the physical and chemical properties of the cleaning solution on the cleaning effect
When the static pressure of the cleaning solution is high, cavitation is less likely to occur, so the effect of ultrasonic cleaning or treatment in a closed pressurized container is relatively poor
The selection of cleaning agents should be considered from two aspects: on the one hand, cleaning agents with good chemical effects should be chosen based on the nature of the dirt; On the other hand, it is necessary to select a cleaning agent with appropriate surface tension, vapor pressure and viscosity, as these properties are related to the strength of ultrasonic cavitation. When the surface tension of a liquid is high, cavitation is less likely to occur. However, when the sound intensity exceeds the cavitation threshold, the energy released by the collapse of cavitation bubbles is also large, which is conducive to cleaning. Liquids with high vapor pressure will reduce the cavitation intensity, and liquids with high viscosity are also less likely to generate cavitation. Therefore, detergents with high vapor pressure and high viscosity are not conducive to ultrasonic cleaning.
In addition, both the temperature and static pressure of the cleaning solution have an impact on the cleaning effect. When the temperature of the cleaning solution rises, the number of cavitation nuclei increases, which is beneficial for the generation of cavitation. However, if the temperature is too high, the vapor pressure in the bubbles increases, and the cavitation intensity will decrease. Therefore, the selection of temperature should take into account the influence on the cavitation intensity simultaneously. It is also necessary to consider the chemical cleaning effect of the cleaning solution. Every liquid has a temperature at which cavitation is most active. The most suitable temperature for water is 60-80℃, during which cavitation is most active.
