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Basic Concerns with Ultrasonic Cleaning | Part 7: Load

Ultrasonic cleaning is a versatile method for precision cleaning a broad range of objects. While it involves a simple process, there are several factors to consider for ensuring the best results. In this series of blogs, we’re examining seven key factors that can impact ultrasonic cleaning.

In this article, we look at the load that needs to be cleaned and how to make sure the ultrasonic cleaning process is as effective as possible.

Aqueous Cleaning

Characteristics of the Load

At the heart of an ultrasonic cleaning process is the load that needs to be cleaned. The material, shape, and size of the load and the contaminants that need to be removed all determine how best to set up and operate the cleaning process.


The object material is critical to consider when preparing for ultrasonic cleaning. For example:

  • Dense materials, such as metals, are good transmitters of ultrasonic waves with effective cavitation at their surfaces, making ultrasonic machines an excellent way to clean them. Materials, such as rubber and soft plastic, absorb more of the ultrasonic energy and dampen the cavitation effect, so it can be more of a challenge to achieve the required results.
  • The chemical composition of the material determines which cleaning fluids can be used in the cleaning process. Some materials can be damaged by strongly acidic or alkaline solutions and need to be cleaned with gentler solutions, possibly requiring a longer cleaning cycle time or a different frequency.
  • The durability of the material determines how vigorously the object can be cleaned. Sensitive and delicate materials can suffer damage and erosion from the cavitation process and may require shorter cleaning times at higher frequencies.

Size and Shape

The size and shape of individual objects and the overall load play a key role in the ultrasonic cleaning process.

Large objects or loads may require higher power or longer cleaning times to ensure that all surfaces are cleaned thoroughly. Objects with complex configurations or a large surface area, such as a heat exchanger with fins, generally take longer to clean than simple objects.

Care must be taken with objects that have complex shapes or intricate details, such as crevices, blind holes, and recessed areas. Ultrasonic machines excel at cleaning hard to reach areas, but the objects require careful positioning to ensure that the cleaning fluid and cavitation can reach all surfaces.


The type and amount of contaminant on the objects affects the cleaning process:

  • Contaminants with lower solubility or that absorb greater amounts of ultrasonic energy need more power or time to remove them.
  • Buildups of contaminant on the surface or in hidden cavities are harder to remove than if there’s an even coating over the surface of the object.

Positioning the Load

The load needs to be positioned in the tank so that all surfaces of each object can be cleaned effectively.

The load should be close to the transducers, but not in contact with the bottom or sides of the tank or with any containers containing immersible transducers. Contact impedes the ultrasonic energy from reaching the objects and can damage the objects and transducers.

The most common positioning method is to suspend the load in the tank using a mesh basket. Objects can also be suspended using a wire or string.

The load should be completely submerged in the cleaning solution within the ultrasonic bath. All surfaces that need to be cleaned must be in contact with the fluid.

Troubleshooting Load Cleaning Issues

If the cleaning process isn’t cleaning the load as well as required, here are some areas to investigate.

  • Is the load too big or dirty?

If the load is very large or there’s a significant amount of contamination to remove, the amount of ultrasonic cavitation may not be sufficient to clean effectively.

If there are multiple objects, it may be better to split the load for cleaning. Alternatively, investigate whether more power, a longer cleaning cycle, or a stronger cleaning solution can deliver better results.

  • Does the cleaning solution reach every part of every object?

If the objects have complex shapes or several objects are being cleaned at once, it’s possible that some surfaces are shadowed by other parts. This can prevent the ultrasonic waves from reaching the hidden surfaces.

Rotating or repositioning objects – either at the start of or during the cleaning process – can ensure all parts are cleaned effectively. Agitating objects can remove air pockets.

  • Are the other factors adjusted correctly?

If the cleaning process isn’t working as effectively as required, it’s worth experimenting with other factors, such as the cleaning fluid, temperature, time, and frequency to find the best combination for the application.

Wrapping Up

In order to achieve the best results possible, it’s important to consider the characteristics of the load to be cleaned and adjust the ultrasonic cleaning factors accordingly.

UPC can provide advice on how best to configure ultrasonic cleaners for the specific load and contaminants in order to achieve optimum results.

If you have questions about your particular application, please feel free to get in touch so we can determine the right course of action for you.

Ultrasonic Cleaners for Rent

We offer a range of our most popular ultrasonic cleaners for rent on a 30-day try-before-you-buy basis or as a long-term rental option. 

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Ultrasonic Cleaners for Rent

We offer a range of our most popular ultrasonic cleaners for rent on a 30-day try-before-you-buy basis or as a long-term rental option. 

Contact Us