Ultrasonic Cleaners: Safety and Efficiency Basics – Part 1
Ultrasonic cleaning is a powerful and effective cleaning technology that’s effective for a huge range of industrial, commercial, and professional applications, from industrial machinery to delicate medical equipment.
But it’s not as simple as filling a tank with water, adding detergent, and powering up the machine.
To get the most from your ultrasonic cleaner, you need to understand a bit about how these cleaners work and how to use them safely and effectively. In this two-part series, we explore the fundamentals and best practices for using ultrasonic cleaners.

How Does Ultrasonic Cleaning Work?
Ultrasonic cleaning works by sending high-frequency sound waves through a cleaning solution in a tank. These waves create microscopic bubbles in a process called cavitation. As the bubbles implode, they scrub away grime and other contaminants from objects in the tank.
Read more about ultrasonic cleaning in our 101 guide.
Getting the best cleaning results depends on choosing a high-quality cleaner and finding the balance between factors like the temperature, ultrasound frequency, and cleaning time. You need to choose the right cleaning fluid and work out how to position the load in the tank. You also need to know how to operate and maintain the cleaner, so it continues to deliver great performance over many years.
Without this approach, you could damage the parts that you’re cleaning or the cleaner itself. You also might be providing an unsafe environment to work in, and you definitely won’t see the expected results from your investment in this technology.
Are Ultrasonic Cleaners Safe for All Materials?
Ultrasonic cleaning is safe for a wide range of materials, including most metals, plastics and composites, glass, ceramics, rubber and silicones, precious metals and stones, and hard-wearing textiles. Despite its power, ultrasonic cleaning is non-abrasive and gentle enough for delicate items, like printed circuit boards and medical equipment.
But some materials aren’t suitable for cleaning with ultrasonics.
These include materials that can be damaged by immersion in a fluid, reactivity to the cleaning solution, or from strong ultrasonic vibrations. For example:
- Porous materials like wood or paper – these materials can absorb cleaning solutions, leading to swelling, warping, and deterioration. Intense vibrations can also weaken these materials.
- Thin glass and gemstones with delicate structures and sensitivities – ultrasonic cleaning can cause cracking, discoloration, and surface damage, affecting the appearance and integrity of the materials.
- Microelectromechanical systems and other sensitive components – these can suffer mechanical damage, misalignment, and failure of tiny parts from the vibrations. Some cleaning solutions can react with sensitive materials, leading to corrosion or other chemical damage.
- Soft or delicate materials and finishes – some soft plastics may melt or deform, some rubber can degrade or become brittle, delicate fabrics may fray or lose structure, and some coatings or finishes may be damaged by ultrasonic vibrations.
We recommend consulting with an expert or testing a sample object before using ultrasonic cleaning for your application. We offer a free test service in our lab or can provide a rental machine so that you can test items on your site before deciding whether ultrasonic cleaning is right for your application.
Choosing a High-Quality Ultrasonic Cleaner
High-quality ultrasonic cleaners will deliver reliable and consistent performance for many years, even with the most challenging applications. Reputable manufacturers use superior components, providing better cleaning precision and reducing the risk of faults and costly repairs. These companies often offer better customer support and warranties.
Certifications like NRTL (Nationally Recognized Testing Laboratory) and CE (Conformité Européenne) play a significant role in ensuring safety and efficiency. When choosing an ultrasonic cleaner, check whether the manufacturer holds certifications such as these to ensure the equipment meets the rigorous safety and quality standards that are essential for reliable operation.
At UPC, for example, we use TÜV, an NRTL recognized in the USA, to test that our products meet stringent safety and reliability standards.
How to Get the Best from Your Ultrasonic Cleaner
There’s no one size fits all for ultrasonic cleaners.
You need to consider your application: the materials, type and level of contamination, required cleanliness, and object size and shape.
Many factors contribute to the cleaning process. Adjusting one factor might require changes to others to ensure optimum performance. For example, using a lower temperature for delicate objects might require a longer cleaning cycle.
The Right Cleaning Solution
Choosing the right cleaning solution – or chemistry – is key to effective cleaning.
It’s best to use cleaning fluids specially designed for ultrasonic cleaning. These solutions are designed to work effectively with cavitation and often contain surfactants, which make it easier to remove contaminants.
Different cleaning solutions are suitable for different purposes:
- Alkaline Detergents remove a wide variety of contaminants from many types of materials
- Acidic Detergents are used for polishing instruments, cleaning electronic parts, and removing oxides or mineral deposits such as limescale
- Enzymatic Solutions break down organic materials such as blood and starches
- Deionized Water is used for delicate materials or very light soiling
- Solvents can quickly dissolve residues such as grease, oil, grime, and carbon build-up
It’s important to follow the manufacturer’s instructions on diluting and mixing fluids to prevent damage to the items being cleaned.
Solvents contain volatile organic compounds (VOCs) and should only be used when no other solution can meet the cleaning requirements. They must be used in ultrasonic cleaners that are designed for the purpose and with strict health and safety procedures.
Cleaning Time, Frequency, and Temperature
The cleaning time, ultrasound frequency, and temperature of the cleaning solution are key factors to consider. They need to be adjusted and balanced together to give the best outcome.
- Cleaning time depends on the material, contamination, required cleanliness, and the size, shape, and density of the object. In general, heavily soiled items may need 5-10 minutes, while delicate items may be clean within 1-3 minutes. The cleaning cycle should be long enough to clean effectively but not too long as this can damage materials.
- Ultrasonic frequency determines the size and power of the bubbles created by the ultrasound waves. Lower frequencies (20-40 kHz) produce larger bubbles and aggressive cleaning for tough contaminants, while higher frequencies (60-80 kHz) produce gentler cleaning for delicate items.
- Temperature affectsthe efficacy of the process. Higher temperatures help speed up the chemical reactions but too high a temperature can lower the force of the scrubbing action and damage heat-sensitive items. Usually, 140°F is optimum for an aqueous solution.
Load Position
The way the load is arranged and placed in the tank is important. Objects must not be in contact with the bottom or sides of the tank or containers with immersible transducers. Loads are usually suspended in tanks using mesh baskets or with wire or string.
Objects shouldn’t obscure each other – it’s better to split multiple objects into separate loads rather than overload the basket or cleaner. It may be necessary to disassemble items with multiple parts to allow thorough cleaning.
The load must be completely submerged in the cleaning solution and all surfaces that need to be cleaned must be in contact with the fluid.
Objects with intricate details, such as crevices and recessed areas, need careful positioning to ensure that the cleaning fluid can reach all surfaces. Agitating or rotating items during cleaning ensures that all surfaces are exposed to cavitation bubbles by removing any trapped air pockets.
Next Time…
In the second article of this series, we look at the best practices for operating and maintaining your ultrasonic cleaner to ensure consistently good results over many years.
If you would like to know more about how we can help with your cleaning requirements, fill in our short form and one of our experts will be in touch with you shortly.