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First, the principle of ultrasonic cleaning
Principle of Ultrasonic Cleaning: Ultrasonic cleaning machine is the ultrasonic generator will be higher than 20KHz frequency vibration signals are amplified by the electric power ultrasonic transducer (shock head) of the inverse piezoelectric effect to convert high-frequency mechanical vibration energy through the cleaning medium acoustic radiation, so that cleaning fluid molecular vibration and produce numerous tiny air bubbles along the ultrasound propagation direction in the negative pressure zone formation, growth, and rapidly closed in the positive pressure area produced thousands of high atmospheric pressure and blasting the moment, the formation of numerous micro- high-pressure shock wave acting on the surface to be cleaned. Namely ultrasonic cleaning in the "cavitation effect." Ultrasonic cleaning machine is based on the "cavitation effect" of the basic principles of work and, therefore, has the ultrasonic cleaning on the inside and outside the complex structure, micro-rough surface, slit, blind holes, corners, dead ends, the component parts are intensive features such as excellent cleaning ability, unmatched by other cleaning methods. As the ultrasonic frequency increases, the bubble bursting increases the number of less impact, equipment, therefore, especially suitable for high frequency ultrasonic cleaning of small particles of dirt without destroying the surface of the workpiece.
Second, the expansion of the cavitation bubble and the burst (the burst) put bubble in a liquid high-frequency (ultrasonic frequency), high intensity sound waves generated. Therefore, any ultrasonic cleaning system must possess three basic components: full bloom cleaning fluid tank, the electrical energy into mechanical energy of the transducer and the ultrasonic generator produces high frequency electrical signals.
Third, the ultrasonic transducer and generator cleaning system is the most important part of the transducer. Existing two transducers, one is the magnetic transducer, made from nickel or nickel alloy; a piezoelectric transducer, the lead zirconate titanate or other ceramics made. Put voltage of the piezoelectric material changes in the electric field, it will deform, and this is the so-called 'piezoelectric effect'. Relatively speaking, the magnetic transducer is changing the magnetic field in the deformed material. Whatever the transducer, usually produced by the most basic factor for the intensity of cavitation. Ultrasonic and other acoustic wave, is a series of pressure points, namely, a turn of compression and expansion waves. If the sound energy is strong enough, the expansion of the liquid phase in the wave is pushed, the resulting bubbles; in wave compression phase, these bubbles burst instantly in liquid, or implosion, producing a very effective impact, particularly for cleaning. This process is called cavitation effect.
Fourth, sound compression and expansion from the theoretical analysis, the bubble burst in the air will produce more than 10,000 psi of pressure and 20,000 ° F (11,000 ° C) heat, and in its moment of shock wave will quickly burst out radiation. Single cavitation bubble energy released is small, but there are several million per second cavitation bubble burst at the same time, the cumulative effect of it will be very strong, resulting in a powerful impact to the dirt surface spalling, This is all the characteristics of ultrasonic cleaning. If the ultrasonic energy is large enough, cavitation in the cleaning fluid throughout the production, so ultrasound can effectively clean the tiny cracks and holes. Cavitation also contributed to the chemical reaction and accelerated the dissolution of the surface film. However, only in a certain region within the fluid pressure below the bubble only when the gas pressure in the cavitation phenomenon in the region, it is generated by the transducer when the ultrasonic amplitude is large enough to satisfy this condition. Cavitation minimum power needed to be said short of the critical point. There are different in different liquid critical point of cavitation, so ultrasonic energy must exceed the critical point to achieve the cleaning effect. That is, only to produce more energy than the critical point of cavitation bubbles for ultrasonic cleaning.
Fifth, the importance of the frequency when the operating frequency is very low (in the range of human hearing) will produce noise. When the frequency is lower than 20kHz, the work becomes not only a great noise, and may exceed the Occupational Safety and Health Act or other provisions of the Ordinance limits the security of the noise. High power is needed to remove dirt without regard to the application of surface damage, usually selected from 20kHz to 30kHz frequency range of cleaning the lower frequency range of the frequency of cleaning is often used for cleaning large, heavy parts or high-density material workpiece. High frequency is generally used for cleaning smaller, more sophisticated parts, or clear the tiny particles. High frequency is also used by the application of surface damage is not allowed. Use of high frequency to improve the cleaning performance in several ways. As the frequency increases, the number of cavitation bubbles increases linearly, resulting in more intense shock wave so that it can enter into a smaller gap. If the power remains unchanged, the cavitation bubbles become smaller, the corresponding reduction in the energy released, which effectively reduces the damage on the surface. Another advantage is to reduce the frequency of the viscous boundary layer (Park Nuri effect), so ultrasound can be 'found' a very small particles.
Sixth, the advantages of ultrasonic cleaning 1. Precision: Because ultrasonic energy can penetrate tiny cracks and holes, it can be used with any component or assembly cleaning. Cleaned parts for precision parts or assemblies, the ultrasonic cleaning is often a special technical requirements to meet their unique cleaning method; 2. Fast: ultrasonic cleaning the workpiece relative to conventional cleaning methods in terms of dust cleaning much faster. Assembly can be cleaned without disassembly. Ultrasonic cleaning can be labor-saving advantages are not to be the most economical way of cleaning; 3. The same: to be cleaned Jian, whether large or small, simple or complex, single or in bulk or in the automatic assembly line, the use of ultrasonic cleaning can be uniform manual cleaning unparalleled cleanliness.
VII, ultrasonic cleaning process and the choice of cleaning fluid cleaning system before purchasing, make the following items should be cleaned Application: a clear piece of material to be washed composition, structure and number, analysis and clearly to remove the dirt, these are decisions What you want to use the cleaning method to determine the application of water-based cleaning fluid or solvent prerequisite. The final cleaning process needs to be done to validate the cleaning experiments. The only way to provide suitable cleaning system, designed cleaning processes and cleaning fluid.
Eight, the choice of cleaning solution cleaning solution taking into account the physical characteristics of the influence of ultrasonic cleaning, in which the vapor pressure, surface tension, viscosity and density should be the most significant factors. Temperature can affect these factors, it will also affect the efficiency of cavitation. Any cleaning fluid cleaning system must be used. Select cleaning fluid should be considered when the following three factors: 1. Cleaning efficiency: choose the most effective cleaning solvent, experiments must be done. Such as the introduction of the existing ultrasonic cleaning process, the use of solvents generally do not change; 2. Simple: by using non-toxic liquid should be safe, simple operation and long life; 3. Cost: the cheapest cost of cleaning solvent used is not necessarily the lowest. Must take into account the use of solvent cleaning efficiency, safety, a certain amount of number of parts cleaning solvents may be highest utilization and other factors. Of course, the choice of cleaning solvent cleaning effect to be achieved, and should be compatible with the cleaning of the workpiece material. Water is the most common cleaning fluid, so the system uses water-based solution is simple, low cost and wide application. However, some materials, and dirt does not apply to water-based solution, so there are many solvents are available.
Nine, both distinguished by the cleaning fluid cleaning system of different water systems: usually by exposure to trough, in which the workpiece immersion. And complex system composed by a number of slots, and are equipped with filtration system, shower tanks, dry tank and other accessories. Solvent system: Multi-gas division for the ultrasonic cleaning machine oil, often with a continuous waste recovery. The process of Ultrasonic oil vapor removal by solvent evaporation tank and the ultrasonic immersion tank consisting of integrated multi-slot system completed. Solvent in the hot steam and ultrasonic agitation together, oil, grease, wax and other impurities dissolved in the solvent was removed. After a series of cleaning processes after the workpiece material under the heat, clean and dry.
Ten, cleaning parts cleaning ultrasonic treatment is another consideration on the parts cleaning, cutting or cleaning parts of the tooling is placed on the design. Cleaning parts in ultrasonic cleaning tank, whether or cleaning parts cleaning parts are not touch bottom of basket. Pieces of the total cross-sectional area cleaning ultrasonic tank cross-sectional area should not exceed 70%. Rubber and non-rigid plastic will absorb the ultrasonic energy technology, it will be cautious of such materials for tooling. Cleaning items should also be insulated special attention. Clothes basket poorly designed, or the workpiece is too heavy Sheng, even the best ultrasonic cleaning system efficiency will be greatly reduced. Hooks, shelves and clean the pieces of the beaker can be used to support