Ultrasonic Systems for Precise Cleaning Applications
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How Ultrasonic Cleaning Systems Are Used to Clean Industrial Lenses

May 29, 2018

Ultrasonic cleaning systems can clean hard surfaces such as glass lenses quickly and effectively, but if there are any special characteristics of the lenses, choosing the correct ultrasonic frequency, power and bath can be important. Low frequencies may wear away or pit surfaces and hot baths or baths with detergents may dissolve or etch even hard materials. Glass itself is usually not affected by ultrasonic cleaning but special coatings, surface treatments or plastic lenses may be damaged. When there is any doubt, it’s important to get the right ultrasonic cleaning system and use the appropriate frequency and power settings for your specific application.

How Ultrasonic Frequencies Can Clean Lenses

Industrial lenses made only of pure glass are ideal candidates for ultrasonic cleaning. An ultrasonic generator produces the high-frequency electronic signal and a transducer immersed in the ultrasonic bath converts the signal to ultrasonic waves in the liquid. The waves create cavitation bubbles in the pressure troughs of the ultrasonic waves and the bubbles collapse again in the wave pressure peaks. This creation and collapse of microscopic bubbles in time with the ultrasonic frequency produces a powerful scrubbing action against the hard surfaces of the lenses. Anything adhering to the glass is removed.

Lower frequencies produce larger bubbles and a robust cleaning action while high frequencies produce smaller bubbles for more delicate cleaning. The power of the ultrasonic cleaning system impacts the amount of time required for cleaning as well. For some contaminants, such as grease and oily residue, a mild detergent helps the cleaning action as does heating the bath to soften such deposits.

Robust cleaning with the addition of detergents and heat cleans pure glass quickly and completely but when the lens has a treated surface or surface film, these measures may cause damage. A more careful, customized approach is required.

Gentle Cleaning of Delicate Lenses

Measures to safely use ultrasonic cleaning systems on all kinds of industrial lenses start with choosing a system that will clean gently while minimizing the time the lens stays immersed in the cleaning solution. The required ultrasonic frequency has to be high enough to avoid damaging coatings that are softer than pure glass. At the same time, many lens coatings are sensitive to lengthy immersion in water, possibly absorbing water, changing color or detaching from the lens surface. The frequency therefore has to be low enough to clean effectively, rapidly removing the particular kind of contaminant that is present.

While the chosen ultrasonic frequency determines the intensity of the cleaning action, the power of the system influences how quickly cleaning takes place. If the power is too low, too few bubbles are generated and the cleaning process takes longer. Exactly the right power level produces the maximum number of bubbles and the fastest cleaning. Even higher levels of power are wasted and don’t influence the cleaning speed.

Heat and detergents are sometimes incompatible with delicate surface treatments of lenses. If the ultrasonic cleaning system is properly configured for maximum cleaning speed, it is often not necessary to add detergents to the cleaning bath or apply heat. The trade-off between duration of the cleaning process and the addition of detergents or heat can be based on the specific lens treatment that has to undergo cleaning. If the coating is very sensitive to exposure in water, heat and a specially formulated solvent may speed up the process and reduce water exposure. In general, cleaning at room temperature using deionized water is the least aggressive and default solution.

Kaijo Offers Ultrasonic Cleaning System Consulting

Custom ultrasonic cleaning solutions are often the most effective and least damaging when delicate surfaces such as those of non-reflective industrial lenses have to be cleaned. Kaijo can suggest the best ultrasonic systems for specific industrial lens cleaning applications based on the company’s extensive experience in the ultrasonic cleaner field. In addition to finding effective solutions for such cleaning tasks, Kaijo can supply components or systems from its complete line of ultrasonic equipment.

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How Long Will Ultrasonic Cleaning Take to Clean My Parts?

May 16, 2018

How long an ultrasonic cleaning system takes depends on the system, the part to be cleaned and the contaminants. For light cleaning action of a part with hard surfaces, a few minutes may be enough. Average cleaning times for common ultrasonic cleaning tasks may range from ten to twenty minutes. For cleaning substantial deposits of caked-on grease or carbon, cleaning may take substantially longer. Even for the most difficult cleaning applications, cleaning with ultrasonic cleaners is generally much faster and effective than traditional cleaning methods.

Powerful Industrial Ultrasonic Cleaners

The time required for an industrial ultrasonic cleaner to effectively clean a part depends on the frequency and the power of the system. The technology uses the action of microscopic cavitation bubbles in the cleaning solution. A high frequency such as 100 kHz and above produces small bubbles and gentle cleaning that takes longer. Low frequencies such as 20 to 40 kHz produce large bubbles and strong cleaning action that works quickly.

High frequencies are used for delicate parts such as semiconductors that could be damaged if the cleaning action of the ultrasonic system is too intense. Low frequencies are used for robust components such as metal car parts with hard surfaces that can withstand strong cleaning action. As a result, parts with soft surfaces or sensitive structures may take longer than to clean than tough, metal parts.

The power of the ultrasonic system also helps determine how quickly the system can clean. If the power is too low, there will be fewer cavitation bubbles to clean the parts and the cleaning will take longer. Just the right power for the size of bath produces the most bubbles possible and results in the fastest cleaning action.

How the Contamination to be Cleaned Affects Cleaning Speed

The speed with which industrial ultrasonic cleaners can remove dirt depends on how heavy the contamination is and the nature of the contaminant. The part to be cleaned also plays a role because cleaning speeds up if mild solvents or detergents are added to the cleaning solution or the bath is heated. If the part to be cleaned is sensitive to the chemicals or could be damaged by heat, these measures can’t be applied and cleaning will take longer.

Ultrasonic cleaners work especially quickly when the contamination is in the form of light dirt or particles. These can be dislodged quickly and rinsed away, leaving completely clean parts. Soft films or materials soluble in water are also removed rapidly. For materials that will dissolve in other chemicals, specific solvents or mild detergents can be used to speed up cleaning. Heat is used to soften contaminants such as hardened grease or oily deposits. In each case, the increased speed of the cleaning process has to be balanced against the ability of the parts to withstand the action of the added chemicals or heat without damage.

Comparatively Fast Cleaning

Although ultrasonic cleaners can take longer for some applications than for others, their overall cleaning performance is much faster than traditional methods involving soaking, scrubbing and pressure washing. Soaking, while it may be effective, is usually very time-consuming and requires the use of expensive, corrosive chemicals. Scrubbing can damage the parts and is labor-intensive. Pressure washing can only be used for robust parts and may not get hard-to-access surfaces clean. Ultrasonic cleaners clean comparatively quickly and completely, even cleaning dead-end holes, interior crevices and textured surfaces effectively.

Kaijo can provide free consulting services to help customers select the best high performance ultrasonic cleaner for their application. Kaijo’s cleaning systems work quickly and clean parts thoroughly. The company has unparalleled experience in field of ultrasonic cleaning technology and can provide expert advice with a quote from its complete line of industrial ultrasonic cleaning systems and equipment.

 

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