5 min read · Power Clean applications team
01How does an ultrasonic cleaner work?
An ultrasonic cleaner is a metal tank with ceramic piezo transducers bonded to its side or base. High frequency electrical energy is converted by the transducers into high frequency sound waves — ultrasonic energy — which create a scrubbing action within the liquid. That energy causes the rapid formation and collapse of minute bubbles: cavitation. The bubbles grow until they implode against the surface of the immersed part, releasing enough energy to lift contamination off the surface and out of the innermost recesses of an intricately shaped component.
02What is cavitation?
The rapid formation and collapse of millions of tiny bubbles, or cavities, in a liquid. They are produced by the alternating high and low pressure waves generated by high frequency sound. During the low pressure phase the bubbles grow from microscopic size; during the high pressure phase they are compressed until they implode.
03How do I get the best ultrasonic cleaning?
There are many variables, but three decisions matter most: choosing the proper cleaning solution, cleaning at the right temperature for the correct length of time, and choosing the right size and type of ultrasonic cleaner for the work.
04Why is a special solution required?
Soils adhere to parts — if they did not, they would simply fall off. The job of the solution is to break the bond between the part and its soil. Water alone has no cleaning properties. The primary purpose of the ultrasonic activity is to assist the solution in doing its job, and increased cavitation results from reduced fluid surface tension. Selecting the right cleaning media is critical and depends on several factors.
05What cleaning solution should I use?
Modern solutions are compounded from detergents, wetting agents and other reactive components, in a wide variety of formulations designed for specific applications. Proper selection is crucial both for acceptable cleaning and to avoid undesirable reactivity with the part. Your Power Clean representative can help identify the optimal stock formulation, or likely candidates to test and evaluate on your components.
06What should I never use?
Flammables and solutions with low flash points should never be used — cavitation energy converts to heat and kinetic energy, creating high temperature gradients and hazardous conditions with flammable liquids. Acids, bleach and bleach by-products should generally be avoided; where they are unavoidable they may be used with indirect cleaning in a suitable container such as a glass beaker. Acid and bleach will damage stainless steel tanks and create hazardous conditions.
07When should the solution be changed?
Replenish when you notice a decrease in cleaning action, or when the solution is visibly dirty or spent. A fresh batch at every cleaning session is usually not required.
08How long should a cleaning cycle be?
It varies with the soil, the solution, the temperature and the cleanliness you need. Visible soil removal should begin almost immediately once ultrasonic action starts. Cycle time is the easiest — and most often misapplied — factor used to compensate for other process variables; an experienced operator can approximate it, but it must be validated with your chosen solution on your actual soiled parts.
09What is the optimum cleaning temperature?
Heat usually enhances and speeds up the process, and most detergent solutions are designed to work best at elevated temperature. The best way to find the optimum is to run tests — but usually the best results fall within the 50 °C to 65 °C range.
10Is rinsing required after cleaning?
Rinsing is recommended, to remove chemical residue that could be harmful to the part. Parts can be rinsed in the ultrasonic cleaner itself using a clean water bath, or in a separate tub of tap, distilled or deionised water.
