If you’ve used ultrasonic cleaning before, you’ve probably noticed that it’s hot stuff. We don’t mean results-wise (though ultrasonic cleaning is the best industrial cleaning technology available), we mean in terms of actual temperature. Most ultrasonic cleaners come with a heating system onboard and tank temperatures of 180°F are seen in some applications.
So what is the role of heat in ultrasonic cleaning, exactly? And how can you use it to your best advantage? Let’s take a look.
How does it work?
In most ultrasonic systems, one or more heating plates are mounted to the side of the cleaning tank. These plates transfer the output of simple electrically powered heating elements through the steel wall of the tank into the cleaning medium.
What is the usual temperature range?
Most ultrasonic cleaning units operate between 130° and 180°F, though some processes operate at as little as 90°F.
What’s the best temperature for cleaning?
This will depend on three factors: Your cleaning solution, the item being cleaned and the contaminants being removed.
- Cleaning solution—Some products carry a manufacturer’s recommendation for operating temperature, so be sure to account for this.
- Item being cleaned—Most ultrasonic cleaning targets can easily handle temperatures throughout the usual cleaning range, but others (such as circuit boards) can warp or suffer other damage in high temperatures.
- Contaminants—Some contaminants need to subjected to high temperatures to be removed in an efficient manner. More importantly, some contaminants become more stubborn when heated beyond a certain point. For example, proteins in blood will harden significantly above about 100°F. In cases like this, there should be little or no heating applied to the solution.
What factors need to be taken into account?
Obviously, the heat delivered into solution by the heating unit on the cleaner is predictable and easily controlled. But we also need to consider the heat created by the cleaning process itself.
The transducers also produce a small amount of heat. A 500 Watt group of transducers will produce around 90 Watts of heat at full intensity. So let’s say a 6 gallon tank configured with 500 Watts of ultrasonics has the heating system set to 140°F and is maintaining that temperature. If the ultrasonics is left on for 4 straight hours beyond that time, the tank’s temperature could increase to over 160°F.
For this reason, it’s important to monitor the cleaning process and ensure that the temperature in the medium doesn’t stray outside the envelope dictated by your cleaning medium, pieces and contaminants.
How does heat affect the process?
Heat has three main roles in the cleaning process.
- Increasing the effectiveness of soaking—In general, warmer liquids are more effective at removing a wide variety of contaminants.
- Gas removal—Dissolved air and other gasses inhibit cavitation; a warmer solution helps these gasses escape, increasing cleaning effectiveness.
- Reduced viscosity—Warmer liquids are less viscous, and lower viscosity means more effective cavitation.
Can we save energy or time when heating?
With the new Sonic Touch® II control system, it’s a simple matter to set up a weekly schedule that automatically heats solutions prior to the cleaning session. This saves time and labor. Plus, the advanced data collection capabilities of the Sonic Touch® II allow operators to analyze the performance of all cleaner subsystems. This makes it possible to determine how to achieve the best heat profile for optimal cleaning.
Contact our knowledgeable staff today and let us guide you through your ultrasonic cleaning questions.