The energy of the high-frequency ultrasonic cleaning machine is very concentrated. Because the energy of the ultrasonic can penetrate the fine gaps and small holes, it can be cleaned with any components or assembly. When cleaning parts are precision components or assembly, ultrasonic cleaning often becomes the only way to clean its special technical requirements.
Introduction to high-frequency ultrasound cleaning technology
The definition of high-frequency ultrasound is equivalent to low frequency. As shown in Table 1, ultrasonic frequency below 50kHz is called low frequency. This frequency band is currently the most widely used in industrial-grade ultrasonic cleaning. Common frequencies include 28kHz and 40kHz. The ultrasonic frequency can be called high frequency in (51-199) KHz, and the common frequency includes 80kHz, 120kHz, and 170kHz.
Table 1 ultrasonic frequency classification list
Ultrasonic classification
Low frequency
High frequency
Micro-vocal wave
Stems
Frequency range (kHz)
20 ～ 50
51 ～ 199
200 ~ 499
500 ~ 999
Common ultrasound frequency (kHz)
20, 25, 28, 40
80, 120, 170
200, 430
750, 950
Studies have shown that the frequency of ultrasound directly determines the strength of the ultrasonic empty effect. The ultrasonic frequency is inversely proportional to the size of the bubble and the energy strength of the empty effect. As shown in Figure 1, the larger the size of the air bubble, the greater the energy released during the rupture.
In developed countries such as Europe, America, and Japan, high-frequency ultrasonic cleaning technology has been adopted in the areas that need to be cleaned. While obtaining good cleaning effects, it has eliminated the damage of low-frequency ultrasonic cleaning on the surface of the workpiece. In China, high-frequency ultrasonic waves are also used in cases of high cleanliness cleaning before the coating of optical components.
In addition, compared with low-frequency ultrasonic, high-frequency ultrasonic also has the advantage that can effectively remove smaller particles. As shown in Figure 2, when the flowing liquid is closer to the solid surface, the flow rate of the liquid is getting closer to 0. This flow speed is The thickness layer of the liquid close to 0 is called the fluid boundary layer. The larger the thickness of the fluid boundary layer, the larger the particle size hidden in the layer, and it is not easy to remove during the cleaning process. The higher the ultrasonic frequency, the more conducive to reducing the thickness of the fluid boundary layer, and more conducive to removing the fine particles hidden in the fluid boundary layer, the thickness of the fluid boundary layer of different ultrasonic frequencies (in the water agglomeration) and the best The size of the particle size is shown in Table 2.
Regarding the optimal application of the size range of the particles, the relevant interpretation is: for the ultrasonic of a specific frequency segment, it has a certain cleaning effect for particles beyond its upper limit range; for particles smaller than the lower limit range, there is no cleaning effect. Therefore, in the process of cleaning, the appropriate ultrasonic frequency must be selected for the size of the excess objects that the workpiece may carry to obtain the expected cleaning effect.
Table 2 Different ultrasonic frequencies The thickness of the fluid boundary layer and the size of the particle size
Ultrasonic frequency (K Hz)
40
80
120
170
Border thickness (& mu; m)
2. 82
2. 2
1. 75
1. 4
Best applicable particle size (& mu; m)
2 ~ 50
1 ～ 5
0. 5 ～ 3
0. 2 ～ 1. 5
Due to its excellent cleaning effect, ultrasonic cleaning has been widely used in many industries. But the lack of traditional low-frequency ultrasonic cleaning limits the application of components that have electrical contacts inside. With the emergence of high-frequency ultrasonic cleaning technology, while achieving a good cleaning effect, the original shortcomings of low-frequency ultrasonic cleaning are also overcome.
