How Ultrasonic Cleaners Work: The Science Behind Ultrasonic Cavitation & Cleaning

Ultrasonic cleaners use high-frequency sound waves to create microscopic bubbles in a cleaning solution — a process called ‘ultrasonic cavitation’. These bubbles rapidly collapse, generating tiny shock waves that dislodge dirt, grease, and contaminants from surfaces. This method is highly effective for cleaning intricate objects like machine parts. 

What Is Ultrasonic Cleaning?  

Ultrasonic parts cleaning offers a highly effective, precise, and eco-friendly alternative to traditional parts cleaning. It provides consistent cleaning, even in tiny and tight crevices. It also removes tough contaminants including rust, scale, grease and carbonised dirt without damage to the parts.
 

How Do Ultrasonic Cleaners Work?  

Ultrasonic cleaning is effective because of a process called cavitation. Here’s how it works:  

1. The part being cleaned is immersed in a tank full of water-based cleaning solution.
   
2. A Piezoelectric transducer converts an electrical charge into sound. This creates high-frequency sound waves that pass through the liquid creating millions of tiny bubbles.
   
3. These bubbles implode in 0.4 milliseconds in a process called acoustic cavitation. This generates immense heat and pressure that dislodges contaminants.  The microscopic bubbles can penetrate even the most intricate geometries, reaching areas that traditional methods cannot.

The Piezoelectric Transducer  

Ultrasonic transducers are piezoelectric, meaning they convert electrical energy into mechanical vibrations using piezoelectric crystals. This generates ultrasonic waves for cleaning applications. 

Unlike other ultrasonic parts washers, Safetykleen’s Sonickleen Eco has its piezoelectric transducer on the side. This is because the loose dirt tends to settle at the bottom of the tank. In bottom-mounted setups, this dirt can accumulate and muffle ultrasonic waves, reducing cleaning efficiency. The strategic placement of a side-mounted transducer means that no area of the bath is shaded from cavitation and, as the transducer is easier to access, maintenance time can be reduced.

Who is Ultrasonic Cleaning for?   

Unlike traditional solvent-based or manual cleaning methods, ultrasonic cleaning is non-abrasive. This reduces the risk of damage to delicate parts. Various industries, including rubber and plastic manufacturing, metalworking, machinery and equipment manufacturing, and aerospace, widely use it.  

 Choosing the Right Ultrasonic Cleaning System  

Choosing the right ultrasonic cleaning system needs careful thought. You should consider the size, volume, and material of the parts you are cleaning. Also, think about the type of contamination. Key aspects to evaluate include:  

• Tank Size and Configuration – Picking the right tank size helps with efficient batch cleaning. Automated systems can also make operations easier.  

• Cleaning Solution Compatibility – Different contaminants require different chemical formulations to optimise cleaning performance.  

• Automation and Ease of Use – Opt for a machine that is easy to load and set up, including for timed or scheduled cleaning.   
• Energy efficiency – Energy efficient machines both reduce your operational cost and improve your sustainability efforts.   

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What Impacts Cleaning?   

What frequency do Ultrasonic cleaners operate at?  

Lower frequencies (20-40 kHz) generate larger, more forceful bubbles that are ideal for heavy-duty cleaning. Higher frequencies (60-80 kHz) create smaller, gentler bubbles suited for delicate, precision-engineered parts.  

What is the best liquid to use in an ultrasound parts cleaner?  

The type of cleaning solution used influences the effectiveness of cavitation. Safetykleen recommends one of three unique cleaning chemicals designed to tackle either carbon, rust and scale, or grease. Safetykleen mixes these cleaning chemicals with our unique purified water for improved efficiency.  

What temperature should I use?  

Heating the cleaning solution to 40-60°C improves cavitation efficiency. This is especially helpful for oils and greases that need higher temperatures to break down.  

FAQs  

What can you clean with an ultrasonic cleaner? 

Ultrasonic cleaners are ideal for removing oils, grease, carbon buildup, and fine particulate contamination from metal components, plastic moulds, and machine parts. 

How does ultrasonic cleaning remove rust? 

It uses cavitation bubbles and rust-removal solutions to break down oxidation, lifting rust from metal surfaces without abrasive scrubbing. 

What Not to Put in an Ultrasonic Cleaner? 

Avoid flammable liquids, parts with loose coatings, fragile plastic components susceptible to warping, and materials that can absorb cleaning solutions. 

Can you use tap water in an ultrasonic cleaner? 

Yes, but using distilled or deionised water with the right cleaning solution improves efficiency and prevents mineral buildup on industrial parts.

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