What is an ultrasonic transducer?
The ultrasonic transducer is a key component in an ultrasonic cleaning machine. An ultrasonic transducer is a device that produces sound above the range of human hearing, usually starting at 20 kHz, also known as ultrasonic vibration.
The ultrasonic transducer consists of an active element, a backplate and a radiating plate. Most ultrasonic cleaners use a piezoelectric crystal as the active element. Piezoelectric crystals convert electrical energy into ultrasonic energy through the piezoelectric effect, in which the crystal changes size and shape as it receives electrical energy.
The backing of the ultrasonic transducer is a thick material that absorbs the energy radiated from the back of the piezoelectric crystal.
What is an ultrasonic transducer?
An electronic ultrasonic generator is a power source. It converts alternating current energy from a power source, such as a wall outlet, into electrical energy suitable for powering a transducer at an ultrasonic frequency. In other words, the ultrasonic generator sends a high-voltage electrical pulse to the transducer.
The principle of operation of the ultrasonic generator is to send electrical energy pulses to the transducer, which converts the energy into mechanical (pressure) waves in the cleaning fluid, which performs a vibratory cleaning action.
While an ultrasonic frequency of 40 kHz is by far the most commonly used frequency for ultrasonic parts cleaning, certain applications do require lower or higher frequencies for best results. For example, larger, heavily contaminated items may use a frequency of 20 kHz, as this produces larger, more powerful cleaning bubbles, but fewer bubbles per second. On the other hand, some very small, delicate items may require a higher ultrasonic cleaning frequency of up to 200 kHz. typically, higher frequencies allow higher levels of intricate detail to be cleaned.
What is the difference between a high-quality ultrasonic cleaner and a low-quality "off-the-shelf" ultrasonic cleaner?
Let's look at some of the sacrifices:
The quality of piezoelectric crystal transducers varies greatly. Due to the nature of crystal formation, the transducer's ability to convert electrical energy into mechanical/acoustic energy naturally degrades over time (typically 3-6 years). Cheap, low quality transducers will decay much faster than transducers made with high quality crystals. This degradation or decay will drastically change the quality of cleaning in an ultrasonic machine. Cheap ultrasonic cleaners may seem to perform well when new, but will usually show degradation in cleaning quality in as little as 3-6 months.
Ultrasonic generators can be made from electronic components that lack the longevity expected by end users. Combined with accelerated piezoelectric transducer degradation, these low-quality ultrasonic generator components can lead to extreme changes in ultrasonic parts cleaner performance over time. This cleaning variability in turn leads to more scrap and reworked parts. Not only does this represent a major cost issue for organizations, but it can lead to processes failing validation protocols and specifications for medical devices, aerospace and other fields.
Low-power ultrasonic transducers can significantly reduce the cost of an ultrasonic cleaner, but this sacrifice also reduces cleaning results. Low-power transducers in ultrasonic cleaners can also affect the ability to uniformly cavitate the solution.
Tank thickness is important. Over time, frequent application of ultrasonic energy to the tank can lead to tank corrosion and possibly corrosion of the bottom of the tank. Signs of corrosion in ultrasonic cleaning tanks include the gray appearance of the stainless steel and pits in the bottom of the tank. Low-quality ultrasonic cleaners that use thinner gauge stainless steel can show wear within a few months.
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