Ultrasonic cleaning is the direct and indirect effect of the cavitation, acceleration and direct flow of the ultrasonic wave on the liquid and the dirt, so that the dirt layer is dispersed, emulsified and stripped to achieve the cleaning purpose. In the ultrasonic cleaning machines currently used, cavitation and direct flow are applied more.
　　 Ultrasound is a sound wave with a frequency above 20 kHz in the human hearing range. The propagation of ultrasonic waves relies on elastic media. When propagating, the particles in the elastic medium oscillate and transmit energy through the medium in the direction of propagation of the ultrasonic waves. Such waves can be divided into longitudinal waves and transverse waves. In solids, both can be transported, while in gases and liquids, only longitudinal waves can be transported. Ultrasonic waves can cause particle vibrations, and the acceleration of particle vibration is proportional to the square of the ultrasonic frequency. Therefore, ultrasonic waves of several tens of kilohertz will generate a great force. When strong ultrasonic waves propagate in a liquid, acoustic cavitation will occur due to nonlinear action. The shock wave emitted when the cavitation bubble suddenly closes can generate thousands of atmospheric pressures around it, and the direct repeated impact on the fouling layer destroys the adsorption of the dirt and the surface of the cleaning member on the one hand, and also causes the dirt layer on the other hand. The damage is removed from the surface of the cleaning member and dispersed into the cleaning liquid. The vibration of the bubbles also scrubs the solid surface. The bubbles can also "drill" into the cracks to vibrate and cause the dirt to fall off. For oily dirt, due to ultrasonic cavitation, the two liquids are rapidly dispersed at the interface to emulsify. When the solid particles are wrapped by the oil and adhere to the surface of the cleaning member, the oil is emulsified and the solid particles fall off. The cavitation bubbles cause a circulation of the liquid itself during the vibration process, the so-called sound flow. He can make the surface of the vibrating bubble have a high velocity gradient and viscous stress, which can cause the destruction and falling off of the surface of the cleaning part. The high-speed micro-jet generated by the ultrasonic cavitation on the solid and liquid surface can remove or weaken the boundary layer. Corrode solid surface, increase the stirring effect, accelerate the dissolution of soluble dirt, and strengthen the cleaning effect of chemical cleaning agent. In addition, the ultrasonic vibration causes a large vibration velocity and acceleration of the mass in the cleaning liquid, and also causes frequent and intense impact on the surface of the cleaning member.
　　 Affect cleaning factors
　　 Cleaning medium: Ultrasonic cleaning, generally there are two types of cleaning agents, namely chemical solvents and water-based cleaning agents. The chemical action of the cleaning medium can accelerate the ultrasonic cleaning effect, the ultrasonic cleaning is a physical action, and the two effects are combined to fully and thoroughly clean the object according to the object.
　　 Power density: The higher the power density of the ultrasonic wave, the stronger the cavitation effect, the faster the speed, the better the cleaning effect, but for the precise surface smoothness of the object, the long-time high-power density cleaning will empty the surface of the object. Chemical, corrosion.
　　 Ultrasonic frequency: It is suitable for rough, dirty and initial washing of workpieces. When the frequency is high, the ultrasonic direction is strong, which is suitable for fine object cleaning.
　　 Cleaning high temperature: Generally speaking, the ultrasonic wave has the best cavitation effect at 50 ° C ~ 60 ° C, the cleaning agent is not the higher the temperature, the more significant the effect, there may be high temperature failure, usually when the ultrasonic wave exceeds 85 ° C The cleaning effect has deteriorated. Therefore, when the ultrasonic cleaning is actually applied, the operating temperature of 50 ° C to 70 ° C is used.