RND: Everything You Need to Know About Ultrasonic Cleaners

What is ultrasonic cleaning?

Ultrasonic cleaning is a method that can be used to clean almost anything, but it is particularly useful for cleaning objects and devices that may have crevasse or intricate parts, and be tough or even impossible to clean by hand. Ultrasonic cleaning is useful in a variety of industries such as electronics, healthcare, jewellery, aerospace and automotive. 

For manufacturers, technicians and engineers, ultrasonic cleaning offers huge benefits that can help maximise the longevity and lifespan of parts and ensure that downtime is reduced with effective cleaning.

Read on to find out why the procedure is so effective and widely used across a range of different disciplines.

How does ultrasonic cleaning work?

The technique is called cavitation. Cavitation refers to the use of mechanical vibrations which produce sound waves in a solution, creating microscopic implosions of bubbles that   bash against the item continually, dislodging and removing contaminants and dirt without the need for harsh chemicals. 

The ideal way to use the tanks is by placing parts in a basket, tray or glass beaker and then immersing them into the cleaning solution. Cavitation affects the whole bath and means that all areas of the component that are submerged will be cleaned thoroughly and evenly, even reaching crevices and tight areas that other cleaning techniques would not extend to. The cleaning solution used can either be water-based or solvent-based. The former is a bit more limited in terms of cleaning effectiveness, but is a greener option for the planet.

What parts make up an ultrasonic cleaner?

An ultrasonic cleaner consists of three parts:

• The generator
• The transducer
• The tank

The generator

In simple terms, the generator is the power supply. It transfers AC power from a wall into an electrical signal to energise the transducer. 

The transducer

The transducer is responsible for generating ultrasonic vibrations, which are at a frequency range above the level of human hearing. Most ultrasonic cleaners in Europe and Asia use piezoelectric crystals to convert electrical energy from the generator to ultrasonic energy. The crystals change size and shape when electricity passes through them and produce linear vibrations. In the past a lot of transducers were metallic, but nowadays most ultrasonic cleaners have ceramic transducers as they offer a gentle clean and are more effective. The transducer is situated under the tank to cause the vibrations above it.

The tank

This is where the part and the cleaning solution is placed, as well as the basket, tray or glass jar used to submerge the part. Tanks can range in size depending on the amount of solvent they can contain. Some tanks, including the range from Distrelec’s very own brand, RND, are fitted with a basket and include temperature control and timer functions. 

Benefits of using an ultrasonic cleaner

1. Gentle cleaning – For more delicate items such as small mechanical parts, ultrasonic cleaners are perfect. This is because the items need a thorough but delicate clean. The cavitation effect used by the cleaners helps to reach crevices and remove unwanted residue without causing damage. 
2. Versatile – Ultrasonic cleaners are ideal for a variety of applications. Automotive shops use them to remove any lubricants or residue from parts, dentists use them to clean small dental instruments and laboratories use them to clean glassware. 
3. Efficient – Compared to other cleaning methods, ultrasonic cleaning is one of the most efficient. It uses less water than most hand-cleaning methods or conventional equipment washing machines. It’s more energy efficient and it works much quicker. 
4. Safer – As well as preventing workers inhaling toxic fumes, the ultrasonic cleaner also eliminates the chance of workers harming their hands on sharp parts or objects. 
5. Convenient and easy – Ultrasonic cleaners are easy to use, as the operator just needs to add the part and detergent into the tank. They’re convenient too as they can be left whilst the operator works on something else. 

Why choose an RND ultrasonic cleaner? 

With an automated and consistent process, RND’s ultrasonic cleaners offer high specification with high performance. The brand’s range provides increased functionality through a three-tiered model of power modes, as well as fluid temperature and cleaning cycle timer controls, included as standard. Take a look below at some of the features of RND Ultrasonic Cleaners:

• Easy-to-read digital display.
• Robust tanks made from stainless steel.
• Time selector for an automated and consistent process.
• Heat selector for more suitable temperatures.
• Energy-efficient (lower water consumption).
• Comes with a basket and lid as standard.

The cleaning procedure

Cleaning modes  

All of RND’s ultrasonic cleaners have three cleaning modes to help achieve the best performance for the task: degas, delicate and full. 

Degas

It is recommended to run a degas cycle before putting the item in the tank. Degassing removes any gas from the liquid. This ensures that surface tension is improved and a more effective clean is carried out. 

Delicate

Delicate mode should be used for a gentler clean, as the power is halved. It is recommended to use this mode combined with an ultrasonic solution for sensitive materials and parts. 

Full

Most suitable for heavily soiled items as this mode uses the ultrasonic cleaner’s maximum power. When used in conjunction with temperature control and an appropriate solution, this mode will ensure a powerful clean.

How to clean 

General cleaning

For lightly soiled objects it is recommended to use warm water with the temperature set to 40°C. Run degas mode and then set a time based on the item to be cleaned, usually 2-10 minutes is long enough to clean items thoroughly. Certain items might need to be cleaned twice depending on the amount of contaminants on them. 

Some machines have longer cycle times, which is ideal for those who require a machine that needs minimal supervision. 

Enhanced cleaning

If the parts require a deeper clean it is recommended to use an ultrasonic solution mixed with the water, you can also set the temperature higher, between 40°C and 60°C.

Extensive cleaning

For particularly heavy soiling, such as hard carbon deposits or rust on non-plated metal, use an extensive clean. Pre-soak the objects in the bath with a strong concentration of solution and then choose full mode at a high temperature.

How to choose the best ultrasonic cleaner for your application

Ultrasonic cleaners can be expensive so it’s essential that you make the right decision when choosing the right one for the task in-hand. Before selecting the appropriate ultrasonic cleaner, take into account the following:

Size

Ultrasonic cleaners come in various sizes, depending on the application or components that need to be cleaned. Prior to purchasing equipment, determine the size and quantity of components you want to clean. Even if the part you want to clean is small, a bigger ultrasonic cleaner would be more suitable if there are multiple parts. 

Particular attention should be paid to the size of the baskets which hold the objects in the tank. During cleaning, parts often need to be fully submerged in the liquid, so it’s important that the user knows the working depth of the cleaning fluid. This refers to the distance between the surface of the liquid and the inside bottom surface of the tank. 

If you require an ultrasonic tank that will fit longer objects then look no further than RND’s 10L tank. It has been specifically designed for longer tanks. 

Ultrasonic frequency

The majority of ultrasonic cleaners operate between 35kHz and 45kHz, which is the perfect range for most cleaning operations. However, a lower frequency of 25 kHz will be more suitable for rough cleaning such as removing polishing paste or lapping abrasives.

The lower the frequency, the bigger the cavitation bubbles that are produced. Bigger bubbles have more powerful implosions, helping to remove the toughest of foreign objects. For more delicate parts like soft metals or intricate electronics, frequencies should be between 80 and 130. Take a look below at the full breakdown of ultrasonic frequency powers:

25kHz – This is great for removing strong pollution and is the most powerful. Do NOT use this frequency on sensitive materials such as glass. 

40kHz – This is the standard frequency power and is effective at removing contaminants on a variety of materials. 

80kHz – Perfect for items with complex geometry and tight spaces as cavitation bubbles can squeeze into small areas to remove pollution. 

120 kHz and megasonic – The main use for this frequency is in precision optics to clean very sensitive parts. It can also be used on clean parts to eliminate any dust in final cleaning. 

Ultrasonic temperature

Using a heated solution can contribute to cleaning tasks being carried out quickly and efficiently. Some ultrasonic cleaners come equipped with thermostat-controlled heaters which can be adjusted to provide heated solutions to boost cleaning results.

Accessories for ultrasonic cleaners

On the Distrelec webshop you can find a range of ultrasonic cleaning accessories from RND. Some of the main ones that are used are baskets and beakers. 

Baskets

All of RND Ultrasonic Cleaners come with the matching basket size and additional baskets can also be bought separately. A wire mesh basket should be used as it helps to minimise and reduce ultrasonic hot spots during the cleaning process. All baskets have convenient handles which overhang the bath lip for safe and easy repositioning during the cleaning cycle. 

Glass beakers

Beakers are the perfect container for small parts like electronic components and jewellery. Beakers are suspended in the tank with the appropriate basket, and the solution is only required in the beaker. Separating parts to individual beakers enables the user to group components together, and use two different solutions at the same time, whilst lowering the amount of solution needed. The beakers are made from borosilicate glass, which is a type of glass that is more resistant to rapid temperature changes. Using the jar means that items don’t get lost and cleaning is faster.

Glass beaker baskets

The Distrelec webshop also sells baskets for the glass beakers. The glass beakers can be placed in these baskets so they can be held safely in the tank and prevent spillage. They are also available in bundles with the glass jars.

How to maintain ultrasonic cleaners

Here are some maintenance tips that will keep your ultrasonic cleaner in fantastic condition:

• Don’t operate the ultrasonic cleaner when the solution is too low as this can damage the transducer. 
• Don’t allow the item to touch the bottom of the tank as this can cause it to scratch the machine.
• Don’t use solutions with high levels of acid or alkaline. 
• Don’t slope the solution to prevent it from running into the device. 
• Make sure the machine doesn’t sit on a wet surface. 
• Regular and proper maintenance of the ultrasonic cleaning machine will help you to get the best performance possible. 

Recommended products

RND Ultrasonic Cleaning Tank 36L

Borosilicate Glass Cleaning Beaker 300ml

RND Ultrasonic Cleaning Basket for 36L Tank