Cavitations produced in a liquid by high frequency – or ultrasonic – sound waves result in streams of liquids essentially “power washing” objects on a microscopic level. What role does temperature play in the process?

As temperature increases, the number of cavitation bubbles at first increase before falling off.

At the liquid’s boiling point, cavitation produced by ultrasonic sound waves introduced into the liquid stops completely.

In addition to a decrease in the number of bubbles, the size and energy of the streams they produce decrease as well. This can be demonstrated by a foil test, where a piece of foil is placed in industrial ultrasonic cleaners. The size and distribution of the holes produced in the foil reveal the characteristics of the cavitation taking place.

At higher temperatures, the holes in the foil are smaller and more evenly distributed. While the force of the cleaning stream is reduced, the overall coverage is increased. Finding the right temperature of operation may involve balancing these characteristics.

A figure of 60 degrees Celsius for a water bath is typically used. Generally, a figure of 65% of the boiling point of the liquid is used. The choice of temperature is often determined by the detergent used in the solution, if any. The detergents often have an optimum temperature, which takes precedence over the optimum temperature for agitation. If an acid is being used as a cleaning fluid, temperatures need to be kept as low as possible to prevent the acid damaging the stainless steel tank used in ultrasonic cleaning.

Next, we examine the effect of frequency on ultrasonic cleaning. The final installment looks at the need and advantages of varying the frequency.

If you would like to learn more about ultrasonic cleaners, feel free to contact one of our ultrasonic cleaning experts toll free at (888) 420-4445 or visit our website.

The ultrasonic process does a more thorough job of cleaning. Contents restoration companies recover more contents for homeowners. Insurance companies save millions of dollars in total loss claims. Restoration companies are more profitable due to increased efficiency.

But what happens when those surfaces are highly sensitive metals and require specialized care?

Because aluminum is such a soft metal, it is susceptible to the cavitation implosions that ultrasound cleaning produces.

The cavitation bubbles can actually scar and slightly etch away the top surface, leaving what looks like star bursts. Couple this with a polished chrome finish, and the scarring looks even more pronounced in comparison.

To protect this very delicate finish, a few alterations to the general ultrasonic cleaning process must be implemented:

• Reduce the temperature of the ultrasonic bath to no more than 130°F;
• Use a reduced pH ultrasonic soap with aluminum buffers;
• Don’t leave the parts in the bath for as long as you normally would when cleaning other metallic items; and;
• Adjust your ultrasonic washer to operate at a higher frequency. Washing the item while alternating between a standard frequency (40 kHz) and a higher frequency (68 kHz – 170 kHz) will give you the best of both worlds — thorough, yet gentle, cleaning.

These modifications will help clean your parts without inflicting visible damage.

Case in point… Forgiato wheels found on Ferraris, Lamborghinis, and other luxury speed cars are often cleaned via ultrasonics because of their sensitivity. In order to get the most efficient cleaning possible without damage to the pristine surface; a mix of 40 kHz and 170 kHz is commonly used. This coupled with a tightly controlled bath temperature, and just the right length of time, produces a clean custom rim. Finished with a quick dip in a hot reverse osmosis bath and you are ready on race day!

To uncover how to optimize these elements, we use our state-of-the-art testing lab located in Simi Valley, California.

We think of our testing lab sort of like a “CSI crime scene lab” and even refer to ourselves as “chemistry detectives”.

Omegasonics has a large library of ultrasonic cleaning protocols for a variety of parts. However, if we get a call regarding an item that we have never tested before, we will have the client send us their dirty and contaminated parts.

That will enable us to test different batches in different chemistries to find the most effective combinations. Time, temperature and orientation are all experimented with and varied. This information is cross-examined by an ultrasonic cleaning process sheet. A process sheet is a detailed series of instructions regarding temperature, time, etc… on how to clean an item along with a cleaning recipe.

After extensive research is conducted, Omegasonics isolates the best ultrasonic cleaning protocol, document the method, and send the items back to our customers along with the correct ultrasonic cleaning process. We can even put the testing on camera and upload it onto YouTube for real time observation.

If you or anyone else knows of an industrial tool or part with an unidentified cleaning process, contact us immediately! We love using our top notch test lab to uncover more ultrasonic cleaning mysteries. It’s elementary, my dear Watson it’s the smarter choice!