How to use ultrasonic cleaning machine In China

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How to use ultrasonic cleaning machine

Description:

Ultrasonic cleaning apparatus according to the cleaning object and the production scale of claim very different composition and structure, can be complex, bulky equipment, can also be very simple structure. Here focuses on the ultrasound frequency power, transducer and ultrasonic cleaning equipment cleaning tank composed of a core part of the quality problems.

1.1 Choose ultrasonic transducer structure

Ultrasound in the low frequency band (20-100KHz), the vast majority of currently commercially single screw clamping sandwich-type piezoelectric transducer (transducer ‘), the difference mainly lies in the structure of the radiator (with stainless steel plate adherend aluminum block) take shape, one is cone speaker; another straight rod shape.

Trumpet-shaped transducer acoustic radiation efficiency than rod transducer high, that the same input power. In the cleaning tank to get a larger acoustic power

And less consumed by the electric power transducer, the transducer thus heat generation is also low. When the input transducer electrical power is the same, due to the area ratio of the rod-shaped radiating horn transducer large, so radiating sound intensity lower surface of the stainless steel plate bonded thereto cavitation corrosion is small. Cleaning tank (or immersion transducers) are living longer. Therefore, the use of trumpet-shaped transducer is better in general, in order to further improve the sound radiation efficiency, broaden the bandwidth, our country developed a semi-perforated structure wideband ultrasonic cleaning transducer

In some cases, such as deep cleaning screw. Should adopt high radiation intensity sound transducer, then the transducer body radiation often have tapered shape focus to improve radiating sound intensity. Such transducers are generally not adhered to the cleaning tank, but directly into the liquid for cleaning.

12 transducer cleaning tank in the distribution and bonding issues

Some current intensity ultrasonic cleaning machine merchandise, or glued to the bottom wall of the cleaning transducers distributed too close, a close arrangement of an input transducer electrical power strength of 2-3 watts per square centimeter, such a high On the one hand will speed up the stainless steel surface (surface in contact with the cleaning fluid) cavitation corrosion and shorten life, on the other hand because of the sound intensity is too high. Will generate a lot of large air bubbles in the vicinity of the surface of the steel sheet, increasing the sound propagation loss, weakening the cleaning action in a place far away from the transducer. Generally used in power intensity of less than 1.5 watts per square centimeter is appropriate (according to stick with steel transducer area calculation). If deep cleaning tank, in addition to the sticky bottom transducer outside the walls of the tank should also be considered bonded transducers. Transducer and cleaning tank adhesive quality on the quality of ultrasonic cleaning machine machine is great. Not only to cement, and requires a uniform layer, there is no shortage of plastic and does not allow the cracks, so to maximize the ultrasonic energy to clean transmission fluid, in order to improve the overall efficiency and cleaning effect. At present, some cleaning equipment to prevent falls from the transducer to the cleaning tank. Take the screw and glue fixation, this connection, although the transducer will not fall, but there are many hidden dangers. If the screw welding quality is poor, for example, is not perpendicular to the surface of the stainless steel plate, the layer is uneven, and even cracks or missing plastic, energy transfer will weaken; on the other hand, if a bad weld will affect the smooth stainless steel surfaces, resulting in accelerated cavitation erosion, and shorten life. One way to judge the quality of bonding, after cleaning tank is filled with water and turn it work for some time, temperature measuring transducer. If a transducer is particularly fast temperature rise in the number of transducers, it indicates that the transducer may be bonded well. Because the acoustic radiation is not good, most of the energy consumed by the electrical transducer to generate heat . Another approach is to individually measure the electrical impedance of the transducer size small signal conditions determine bond quality. Spot Welder

There are still some vague understanding in terms of performance ultrasonic cleaning machine: that the greater the power, the more the number of transducers, the better the performance, the higher the value, even this Lunjia this understanding is not comprehensive… As described above, transducer cloth too dense, the power density is too large, not only the cleaning effect is not good, and the groove bottom easy cavitation corrosion. On the other hand, is currently the subject of an ultrasonic cleaning machine power commodities mostly electric power instead of sound power, If the label refers to the power consumption of the power frequency, the ultrasonic cleaning machine quality will be judged by the efficiency. If efficiency is low, in the same cleaning effect is large power consumption, but increased user fees. Efficiency ultrasonic cleaning machine consists of two parts one ultrasonic frequency power efficiency that input transducer frequency electric power consumption of electric power engineering percentage frequency;. The other part is the electro-acoustic conversion efficiency, that is, into the cleaning solution acoustic power percentage of the electrical power input transducer. At present, China has not a simple method and apparatus for measuring the electro-acoustic conversion efficiency in industrial production. The subject of the power of the manufacturers of ultrasonic cleaning machine is ambiguous, there is an urgent need for a unified industry standard.

2. Factors affecting ultrasonic cleaning effect

The main mechanism of ultrasonic cleaning ultrasonic cavitation ultrasonic cavitation intensity and acoustic parameters, physical and chemical properties of the cleaning fluid and environmental conditions, and so to get a good cleaning effect must select the appropriate acoustic parameters and cleaning fluid. 21 sound pressure or sound intensity in the selection of the cleaning solution only sound pressure amplitude of the alternating negative pressure appears more than static pressure of the liquid. The intensity of the negative pressure must exceed the liquid to produce cavitation. Liquid cavitation minimum sound intensity or sound pressure amplitude threshold called cavitation. Various liquids with different cavitation threshold in the ultrasonic cleaning bath sound intensity is higher than the threshold of cavitation can generate ultrasonic cavitation. For ordinary liquids, cavitation threshold is approximately 1/3 watts per square centimeter (sound pressure thousand square than in sound intensity). When the sound intensity increases, the ratio of the maximum radius of the initial radius of cavitation bubbles increases, cavitation intensity increases, the sound intensity is higher, the more intense cavitation. conducive cleaning effect. The bigger the better, but not sound power, sound intensity is too high. Will generate a lot of useless bubbles, increased scattering attenuation, forming the sound barrier, but also increase the sound intensity increases nonlinear attenuation, so far away from the sound source will weaken local cleaning effect . For some hard to clean dirt, such as metal oxide surface, chemical fiber spinneret hole cleaning dirt, you need a higher sound intensity at this time is close to the sound source surface should be cleaned, then most do not using trough cleaner. The rod-like focus transducer directly into the cleaning fluid near the surface of the cleaning member for cleaning.

2.4 Effect of Ultrasonic cleaning effect of other factors

Cleaning fluid flow rate has a great influence on the ultrasonic cleaning effect. Preferably stationary during cleaning liquid does not flow. In this case the bubble growth and closing movement to fully complete. If the flow rate of the washing liquid is too fast, some cavitation nuclei are flowing liquid away some cavitation nuclei in no time left to reach the entire growth process closing movement of the sound field, thus making lower total cavitation intensity. In the actual cleaning process sometimes avoid dirt adhering to the cleaning member again. Cleaning fluid flow requires constant updating, and you should pay attention to the cleaning liquid flow rate is not too fast, so as not to reduce the cleaning effect.

Acoustic properties and arrangement of parts to be cleaned in a cleaning bath has a greater influence on the cleaning effect of the sound absorbing large cleaning member, such as rubber, cloth and other cleaning effect is poor, while the intensity of the reflected acoustic cleaning member, such as a metal member good cleaning effect of glass products. Cleaning pieces small area on one side towards the sound source emissions should be arranged to have a certain distance. Cleaning parts not directly on the bottom of the wash tank, especially heavy cleaning parts. To avoid vibration shadow groove floor, but also to avoid abrasions clean pieces cavitation plate accelerate corrosion. The best pieces are hanging in the wash tank, or with a metal Luo Sheng good hanging basket, but must pay attention to use a wire made of. And as far as possible to make a space large baskets with salty filaments to reduce the sound absorption and shielding .

Content of the gas in the cleaning solution for ultrasonic cleaning effect is also affected. In the cleaning solution, if there is residual gas (non-cavitation nuclei) increases the transmission loss, in addition to the diffusion in the cavitation bubbles during the movement to the gas bubbles, at the time of the collapse of cavitation bubbles will reduce the strength and weaken the shock wave cleaning action. So some ultrasonic cleaning device has a degassing, first performed in the boot below the cavitation threshold power level for the vibration, the vibration mode pulsed or intermittent degassing and the power applied to the normal level of cleaning power ultrasonic cleaning; Some ultrasonic cleaning device with a so-called vacuum suction means {degassed), whose purpose is also to reduce the residual gas in the cleaning solution.

Standing wave effects. The cleaning tank is limited space, the ultrasound to the liquid surface by the sound source propagates. At the interface of liquid and gas will be reflected back to form a standing wave. Standing wave is characterized by a minimum pressure in the liquid space of some parts of the sound, while in other places sound pressure. This will result in non-uniform cleaning of the phenomenon. To reduce the influence of the standing wave, sometimes cleaning tank made specifically to avoid the formation of irregular shape of the standing wave. Sometimes the way to take the sweep of work in terms of ultrasonic power, at a minimum so that the sound pressure is not fixed in one place but to keep moved in order to achieve a more uniform cleaning.

Select the 22 frequency

Ultrasonic cavitation threshold and is closely related to the frequency of the ultrasonic frequency, the higher the cavitation threshold, in other words, the higher the frequency, the liquid cavitation to produce the desired sound intensity or sound power greater; frequency low, cavitation prone, while at low frequencies, the effect of the liquid by the compression and rarefaction of a longer time interval. Before collapse of the bubble can grow to a larger size, increased cavitation intensity, beneficial cleaning effect. Currently operating frequency ultrasonic cleaning machine cleaning object according broadly divided into three bands; low-frequency ultrasonic cleaning (20 to 50KHz), high-frequency ultrasonic cleaning (50-200KHz) and megahertz ultrasonic cleaning (700KHz to 1MHz a) low-frequency ultrasonic cleaning. for large parts surface or the surface dirt and cleaning combined with high strength applications. The frequency of the low-end, high-cavitation intensity. Corrosive cleaning the surface, suitable for cleaning the surface finish of the parts, and the frequency of large .40KHz cavitation noise around, the sound at the same intensity, the number of cavitation bubbles generated when more than the frequency of 20KHz, strong penetration advised complex surface shape of the workpiece or blind hole cleaning, cavitation noise is small. but lower cavitation intensity, suitable for cleaning the surface to be cleaned of dirt and weak binding of the occasion, the high-frequency ultrasonic cleaning is suitable for computers. Fine cleaning microelectronic components, such as disks, drives, cleaning head, and a liquid crystal flat panel display glass, micro-component and polishing metal parts, etc. These objects require cleaning in the cleaning process can not be subjected to the cavitation corrosion. To be able to wash micron dirt. Megahertz ultrasonic cleaning is suitable for integrated circuit chip, wafer cleaning and book film. To remove micron, sub-micron contaminants and cleaning member without any damage. Because at this time does not produce cavitation. Its cleaning mechanism is the sound pressure gradient. Role acoustic particle velocity stream. Strong directional characteristic is clean, the cleaning member is disposed generally parallel with the beam direction.

Selection of Ultrasonic Power
Ultrasonic welding principle