Effective Rust Removal With an Ultrasonic Cleaner
With time and exposure to the elements, rust is inevitable on metal surfaces. It could affect parts of your car’s carburetor, small spare parts you keep, tools you are working with and other such objects. Rather than dispose of these pieces as unusable, a good cleaning in an ultrasonic cleaner can help redeem them.
Rust needs a bit of a vigorous cleaning hence you need a good quality ultrasonic cleaner. Your cleaner should be one that can run for at least half hour. Once you’ve figured the ultrasonic cleaner model that you want to use, the rest is easy. You only need to wipe off loose rust fragments from the surface of the material. Plug in the ultrasonic cleaner; fill the tank to the prescribed level with an appropriate cleaning solution, switch it on for a while to disperse the sound field throughout the liquid, and then submerge the pieces using a hanging basket. Let it operate for around half hour.
Millions of microscopic bubbles are created in an ultrasonic cleaning tank by alternating waves of expanded and compressed ultra sound. This process is known as cavitation. The bubbles are formed during the expansion cycle and implode during the compression cycle. A highly energetic liquid stream is released upon implosion, which strikes the surface of the object, dislodging the contaminants that adhere to it.
The ultrasonic cleaning process is able to do what manual cleaning cannot hope to achieve and that too in half the time and effort it would take. A microscopic view of the process will actually show you a vortex being created in the middle of the bubble. Fact is, ultrasonic cleaning is the only solution when you have objects with complex geometries and intricate structures that are hard or impossible to reach with manual tools.
Once done, take a look at the pieces. For stubborn rust stains, you may need to operate another cycle. If you still find small pockets of rust after the second round, you may have to sandpaper it manually. This solely depends on the piece being cleaned, its tolerance for abrasive treatment versus the comparatively gentler ultrasonic action. But this stage is rarely necessary. As far as possible, do not take an abrasive material to rust surfaces. After the cleaning, make sure you spray on an anti-rust primer to protect the surface.
It is extremely important that a right cleaning solution is used. Plain water can be used for cleaning, but it is advisable to use a surfactant that will bind and ultimately remove the dirt. Detergent powder is a common surfactant but for ultrasonic cleaning it is better to choose a solution that is suited for your type of object. In the case of rust acidic solutions are usually best. This would mean that its pH level would have to be 2 to 4. However, you need to weigh this in the light of what other compounds are present in your object. For example if your object contains plastic parts and aluminum surfaces, either disassemble the piece or manually remove as much rust as possible and then use a milder cleaning solution.
Ultrasonic cleaners are ideal for removing rust though care must be taken with objects that are composed of more than one material.
This article was written by Dr. Bob Sandor, a Director at Tovatech, a leading North American supplier of ultrasonic cleaners. When not busy running his company, he explores his fascination with the many aspects of various scientific & industrial devices. For more information on this article visit the Tovatech site from any of the above links.