As the science and technology develops rapidly, the ultrasonic technology has been applied in the various fields of human life. It can be utilized for distance measurement, velocity measurement, cleaning, welding, stone breaking and sterilization and disinfection. It is also applied extensively in medicine, military, industry and agriculture. Though it is known to all, people still have little knowledge of the application of ultrasonic device in cleaning industry.
First of all, the major definition for ultrasonic cleaner is to clean the dirt on the device.
The main principle for ultrasonic cleaner is to transform the acoustic energy of power ultrasonic frequency source into mechanical vibration through transducer, and making it pass through the cleaning slot wall. With the help of irradiated ultrasonic, the microbubble of the fluid in cleaning slot can maintain vibrated under the impact of ultrasonic. The ultrasonic of tens of kilohertz can produce enormous impact power, when the ultrasonic is diffusing in the fluid, the bubble will grow rapidly, then it will close suddenly, the direct and repeated explosion of impact power on pollution layer can clean the solid surface, in the meantime, the bubble will “drill into” the crack and vibrate, on the one hand, breaking the attachment on the surface of polluted materials and objects; On the other hand, leading to the damage on pollution layer, getting out of the object surface and making it scatter into the clean-out fluid.
1. Having a Knowledge of Ultrasonic
The ultrasonic can be divided into three types, namely, infrasonic wave, acoustic wave and ultrasonic. The frequency of infrasonic waves is below 20Hz; Its acoustic wave frequency is from 20Hz to 20kHz; The frequency of ultrasonic is above 20kHz. Among them, the infrasonic wave and ultrasonic cannot be heard by people. Due to its high frequency and short wavelength, the ultrasonic processes good diffusion direction and strong permeability, this is the reason for designing and fabricating ultrasonic cleaners.
2. How Does the Ultrasonic Accomplish Cleaning Work?
Ultrasonic cleaning means to take advantage of its socialization, velocity acceleration and direct inflow effects in fluid to exert direct or indirect influence on fluid and dirt, making the polluted layers become scattered, emulsified and removed, so as to reach the purpose of cleaning. At present, the cavitation and direct inflow effects are the most applied for ultrasonic cleaners.
(1) The cavitation effect: The cavitation effect means to utilize the ultrasonic with compressing force over twenty thousand times for each second to penetrate the fluid in the method of reduced pressure interactive high-frequency conversion. Under the impact of reduced pressure, there is a phenomenon of vacuum nuclear group bubble in fluid, with the impact of compressed force, the vacuum nuclear group bubble can produce strong impact force under pressure crushing, therefore, the dirt on cleaned object surface is removed, thus realizing the purpose of precise cleaning.
(2) Direct inflow effect: The flow phenomena produced along the acoustic diffusion direction by ultrasonic is called direct inflow. When the acoustic wave strength is at 0.5W/square centimeters, the direct inflow can be observed by human eyes, producing flow by maintaining perpendicular to vibrated surface, the flow velocity is about 10cm/s. The macro oil dirt on the cleaned object surface can be mixed with this direct inflow, the clean-out fluid on the dirt surface also produces convection, the solvent for dissolving dirt mixes with the new solvent, making the dissolving velocity become more quickly, which exerts great influence on the transfer of dirt.
(3) Accelerated velocity: The accelerated velocity produced promoted by liquid particles. For the ultrasonic cleaner with relatively higher frequency, the cavitation effect is not prominent, at this moment, mainly depending on the ultraprecise cleaning of accelerated velocity striking particles on dirt under the impact of fluid particle ultrasonic.
3. What is the principle of ultrasonic cleaner?
The ultrasonic transducer can transform the high-frequency vibration electric signal into high- frequency mechanical vibration, radiating in the clean-out liquid in the form of longitudinal wave. During the half-wave of radiation wave expansion, the compactness of clean-out liquid can be damaged and form numerous bubbles with the diameter from 50 to 500m. Such bubbles are filled with solution steam. During the compact half-wave, the bubbles will close quickly, producing partial liquid compact for hundreds of Mpa. Such phenomena is called cavitation effect. Under the constant influence of cavitation effect, the dirt on the surface of hidden part of workpiece will explode and drop. In the meantime, under the impact of ultrasound, the penetration capability of clean-out liquid becomes stronger; The pulsating mixing is intensified; The dissolution, scattering and emulsification is accelerated; Therefore, the workpiece will be cleaned up completely.
Int the field of hydrocarbon cleaning, the ultrasonic device is helpful. For the ordinary grease-removal cleaning, it can be realized by simple soaking and wiping. But for the condition with blind hole and heavy dirt, the ordinary soaking and wiping can not realize the cleaning effect, and some precise components have extremely high requirements for the cleanliness of workpiece surface, the ordinary cleaning can not achieve the desired effect. Therefore, when the ultrasonic device appears, it brings great convenience for cleaning field. With the constant development of manufacturing industry, there is increasingly higher requirements for the precision of precision-removal components, the high precision cleaning device as vacuum ultrasonic device was born at the right moment.
4. What are the composing parts for ultrasonic cleaners?
The ultrasonic cleaner is primarily composed of two parts of ultrasonic cleaning trough and ultrasonic generator. The cleaning trough is made of high quality stainless steel with hard, elastic and corrosion resistance nature, the ultrasonic transducer vibrator is installed at the bottom; The ultrasonic generator can produce high frequency and pressure, transmitting to transducer by means of cable connection wires, the transducer can cooperate with the vibration panel to produce high frequency and sympathetic vibration, thus making the solvent in cleaning trough to clean the dirt under the impact of ultrasonic.
5. What are the characteristics of ultrasonic cleaners?
Comparing ultrasonic cleaning with various chemical, physical, electrochemical and materialized cleaning methods, it possesses the following unique advantages:
It can clean the various dirt on the workpiece surface quickly and completely.
It can clean the precise components in complicated shapes with cavity and trough.
Don’t damage the workpiece surface.
Various solvents can be applied.
The cleaning can be accomplished at room temperature or certain warmer temperature (about 60℃)
The one-piece structure is easy to move.
Saving solvent, cleaning paper, energy, working field and manual work.
6. The ultrasonic cleaner effect
It will certainly be effective, but there are some factors such as cleaning medium, power density, ultrasonic frequency and cleaning temperature will influence the final effect
Cleaning medium: Two kinds of clean-out fluid can be applied for cleaning, it will also be acceptable without them. Generally speaking, chemical solvent and water-base clean-out fluid can be selected. The chemical function of cleaning medium can promote the quick cleaning effect, thus assisting the original physical function of ultrasonic cleaning, then it can be cleaned completely and sufficiently.
Power density: The cavitation effect will become stronger with higher density for machinery power, quickening the velocity, thus improving the cleaning effect, but for precise objects with higher surface cleanliness, the application of high power density cleaning for a long time will produce cavitation and corrosion on the object surface, therefore, ultrasonic cleaning can not be applied for the fallowing objects: cymophane, pearl, jadeite, tanzanite, malachite, emerald, ruby, lapis lazuli, coral, organic gemstone, opal, turquoise, emerald, untrimmed and micro-trimmed jewelry, pearl jewelry, jade, and stones with severe cracks.
Ultrasonic frequency: The high frequency will always lead to high ultrasonic directionality, which is suitable for the cleaning of refined objects.
Cleaning temperature: The temperature range from 50°C to 60°C has the best effect, but it’s worth noting that some clean-out liquid will lose efficacy at high temperature. Generally speaking, when the working temperature exceed 85°C, the effect will become worse. So while utilizing the machine, the water temperature should be controlled around 50℃.
7. Will the ultrasonic cleaning damage the cleaning materials?
Ultrasonic cleaning is safe for most workpieces. The internal explosion of thousands of bubbles for each second can produce enormous energy, however, because the energy is concentrated in the extremely tiny regions, therefore, the whole cleaning process is safe. It should be cautious enough for selecting the clean-out fluid considering the safety. The potential damage on certain workpiece surface by clean-out fluid will probably increase due to the application of ultrasonic. Ultrasonic cleaning can not be applied for the following jewels: cymophane, pearl, jadeite, tanzanite, malachite, emerald, lapis lazuli and coral.
