Ultrasonic Systems for Precise Cleaning Applications
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How Ultrasonic Generators Work to Provide Optimum Cleaning Results

June 27, 2018

Ultrasonic generators produce the high-frequency electric signal that is required for an ultrasonic cleaning system to operate effectively. The devices are powered by normal 60 KHz electric circuits and use electronics to generate ultrasonic frequencies between about 20 kHz and 1 MHz. Piezoelectric or magnetorestrictive transducers convert the electric signal to ultrasonic waves in the cleaning solution. Ultrasonic generators are an important part of the ultrasonic cleaning system as they control the frequency, and also insure that the selected frequency and power output are maintained.

The Role of Ultrasonic Generators in an Ultrasonic Cleaning System

Ultrasonic cleaning systems work by using high-frequency sound waves in a cleaning solution to remove dirt and surface contaminants from a variety of parts and products. When the systems are selected with the right characteristics for an application, they work quickly and efficiently to completely clean items submerged in the cleaning tank. Even irregular parts and components with holes or crevices are cleaned wherever the cleaning solution can penetrate. The systems remove the need for corrosive chemicals, soaking and mechanical scrubbing.

The cleaning performance of ultrasonic cleaning systems depends on the action of cavitation bubbles created by the ultrasonic waves in the cleaning solution. These bubbles form in sound wave pressure troughs and collapse in the pressure peaks, delivering intense scrubbing action on the surfaces of the immersed parts. The transducers placed in the cleaning liquid create the sound waves by vibrating at the selected ultrasonic frequency produced by the ultrasonic generators. The whole system has to have matching characteristics with the frequencies, power, tank size and controls forming an integrated system that works together in a specific cleaning application.

In such a system, the ultrasonic generator plays a key role. Depending on the size of the parts to be cleaned, the nature of the parts, the type of contaminant and the projected use of the system, the generator voltage, power, frequency and other characteristics can be determined. Choosing the right generator affects the performance of the entire system.

How to Choose the Ultrasonic Generator

The ultrasonic frequency generator has to fit into the production environment while at the same time match the cleaning application requirements. Factors making it suitable for a facility include the operating voltage, the size and the type of use. For a particular cleaning application, the selected frequency, power and controls are important. Once the specific cleaning application requirements are defined, selecting the right frequency and corresponding transducers and cleaning tanks is clear.

If a cleaning system is always used the same way, to clean one kind of part made of the same material, a single-frequency generator is the most cost effective option. In manufacturing operations machined parts made from softer metals (i.e. aluminum) will require gentler cleaning from using a higher frequency generator at 78 kHz, while the same part made from a harder metal (i.e. steel) can be cleaned best using of a low frequency generator at 26 kHz. Generally, low frequencies produce intense cleaning action for parts or components made from harder materials while high frequencies provide gentle cleaning of parts or components made from softer materials. In all cases, the ultrasonic generator power must be high enough to fill the cleaning tank with ultrasonic waves, and the system design must ensure that the wave pattern is uniform for the most effective cleaning action.

Kaijo can Help Select the Best Generator

Kaijo’s generators are available as part of a complete ultrasonic cleaning system or as individual components. The complete line of generators ranges from small, desktop units to 1200 W industrial cleaners. Their advanced control systems ensure consistent and quick cleaning action even for difficult cleaning tasks. Kaijo can advise what generators and systems are best suited for a customer’s specific cleaning application and can recommend the corresponding equipment. For a free consultation or quote on using any of Kaijo’s products call 408 675-5575 or email [email protected].

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How an Ultrasonic Generator Works

August 17, 2017

How an Ultrasonic Generator WorksThe ultrasonic generator is at the heart of ultrasonic cleaning systems as it produces the high-frequency signal that the ultrasonic transducers convert to sound waves in the cleaning solution. In addition to generating the signal, the unit can control the frequency and the power, produce several or a range of frequencies and act as part of an integrated, turnkey solution or independently to power separate transducers. Ultrasonic generators need to be selected to match specific cleaning requirements in order for the system to work effectively. Key criteria for generator selection are the power and frequency of the generator and the matching transducers. In each case, the cleaning tank has to be large enough to hold the longest part to be cleaned, the power has to be high enough for the tank size and the frequency has to match the type of contaminant and the mechanical strength of the parts to be cleaned.

How It Works

An ultrasonic generator converts the 60 Hz facility power to high frequencies ranging from about 20 kHz to the 1 MHz range. Some models can generate only a single or a few frequencies while others can produce a wide range. Different levels of power are also available. For multiple-frequency models, operators can select the frequency that is most appropriate for their cleaning application.

In addition to producing the high-frequency signal, ultrasonic generators control the signal to maximize cleaning performance. Generators may automatically adjust the signal to compensate for heavy or light loading of the cleaning tank and they may “sweep” the signal, varying the frequency slightly to eliminate resonance or standing waves in the cleaning tank. For example, when a generator is operating at 38 kHz, varying the frequency randomly between 36 and 40 kHz eliminates hot spots and tank resonance that could damage the parts to be cleaned.

Selecting the Right Model

The right frequency is the key to effective ultrasonic cleaning. Low frequencies in the 26 to 38 kHz range produce large, energetic cavitation bubbles in the cleaning solution. The cleaning action is powerful but fragile components may be damaged and soft surfaces may suffer pitting. This range is suitable for items such as machined parts, glass and wires.

For the mid-frequency range of 78 to 160 kHz, the cavitation bubbles are smaller and the cleaning action is gentler. Hard disk drives, solar panels and ceramic parts can be cleaned at these frequencies. The most delicate components can be cleaned at the highest frequency ranges of 450 to 950 kHz. These frequencies are suitable for semiconductors, LEDs and fragile medical components.

If the ultrasonic generator is used with a single process and always has to clean the same kind of parts, selecting a single-frequency model makes sense. For general-purpose facilities, where the ultrasonic cleaning system may be used for many different cleaning applications, a generator that can produce many frequencies is a good choice.

Kaijo Ultrasonic Generators

Kaijo has a complete line of ultrasonic generators and offers free consulting to make sure customers select the type of system best suited to their cleaning applications. Generator models include the Quava high power, the Quava Mini and the Phenix Legend ultrasonic generators. Models are available as separate components or in turnkey packages.

The Quava high power models include generators that can operate at either multi-frequencies of 26/78/130 kHz or 38/100/160 kHz or ten different single frequency systems from 26 to 950 kHz. The Quava mini is a self-contained, compact tabletop system for small cleaning jobs. The Phenix Legend has 4 single frequency systems of 78kHz, 100kHz, 130kHz and 160kHz. Kaijo can help customers select the right ultrasonic components for a new process tank or help convert an existing tank.

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