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Piezo Transducer For Cleaning Use |
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16 Mar, 2015 |
Ultrasonic Transducer |
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The piezo transducer plays significant role in cleaning use, as we know there are many advantages of using ultrasonics in cleaning process, it can greatly enhance cleaning speed with less cost and without the contact of the labors. Besides, do you understand the working of piezo transducer in cleaning use?
Let's read the following texts to find the answer of question.
Piezo transducer components
In common cleaning applications, piezo ceramics are used to transmit 70% to 90% of applied energy into the cleaning liquid. The piezo meterials of PZT-4 or PZT-8 are now widely used in manufacturing transducers because of their low cost and stable capability.
The assembly of such a piezo transducer is shown in Fig1. It consists of a bolt, two piezo ceramic rings, two metal electrodes, a steel back plate and an aluminum radiating cone.
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In order to deliver more power to desired direction, the mass of aluminum cone is taken smaller than steel back plate, which allows higher amplitude displacement through the aluminum.
We use horn-type transducers in general due to their larg action area. In addition, the straight type transducers have characters of small radiating surface but high sound intensity, applicable for the occasions of great distance cleaning such as deep screw hole. So we can select the suitable structure of piezo transducer for specific cleaning use. |
Cleaning principle of piezo transducer
The Fig2 shows a simple ultrasonic cleaning system, which consists of an ultrasonic generator, several piezo transducers and a tank.
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The piezo transducers are mounted at the bottom of the tank which is made up of stainless steel. The cleaning liquid, which may be either aqueous or solvent, is filled in the tank.
The ultrasonic generator provides a suitable a.c signal to the cleaning transducers to drive the transducer vibrating in its resonant frequency. The vibrations are transferred into the liquid medium through the stainless steel tank.
So that, the formation of cavitations takes place. Due to the collapse of cavitations, a tremendous amount of energy is released. These energies produce an intense local scrubbing action on the material, which is immersed in the liquid. |
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Frequency of piezo transducer
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Generally speaking,
frequency of 20 ~ 40khz can meet the requirement of most industrial cleaning.
However, for some specific precision cleaning such as LCD, semiconductors, optics, etc, traditional frequency not only can't achieve the cleaning requirements, but also may cause the damage of the workpiece. At this point, the high-frequency ultrasonic cleaning provides the solution for us.
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Why high-frequency cleaning can help us to avoid injury? In fact, the strength of cavitation effect is very relevant to the frequency. Higher frequency generates the smaller the cavitation bubbles, so the energy is weak. For example, the cavitation intensity of 40khz is only about one - eighth of 25khz. Besides, at the same sound intensity,
high frequency can generate much more cavitation bubbles than the low frequency, it's very suitable for the workpiece with complex shape or blind hole.
In brief
, appropriate frequency of piezo transducer is of great importance to cleaning result.
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