Ultrasonic cleaners use sound waves and the cavitation effect of rapidly collapsing bubbles in a liquid bath to thoroughly clean objects placed in them. While ultrasound and the cavitation bubbles it produces will produce a cleaning effect by themselves, they are most effective when used in conjunction with a cleaning solution added to the water bath.
Solvent Free Ultrasonic Cleaning
When you’re looking for an effective cleaning solution for your workplace, you might be thinking that your only options will include solvent based, offensive smelling and powerful chemicals. However, when you choose ultrasonic cleaning, you’ll be using a powerful cleaning system that is completely solvent free. Because many people are unfamiliar with the process of ultrasonic cleaning, it’s important to learn how this process can be so effective without solvents.
Learn more about solvent free ultrasonic cleaning and find out how you can use this cleaning tool in your workplace.
The Power of Cavitation the Ultrasonic Cleaning Solution
To effectively remove contaminants from your products, there are certain important steps that must be taken. For example, at the microscopic level you need to break the chemical bonds that allow contaminants to attach to a surface. In most cleaning processes, solvents are used to weaken these chemical bonds so that you can easily scrub contamination away.
Ultrasonic cleaners work on a different principle. Instead of weakening the chemical bonds through the use of solvents, ultrasonic cleaners use the power of cavitation.
Cavitation works by directing millions of tiny, high energy bubbles at the surface of a product. When the bubbles collide with the surface, they release their energy and break the chemical bond, which loosens the contaminants and cleans your machine parts.
At this point, you may be wondering how the bubbles produced during the cavitation process are able to hold together. The answer, simply, is surface tension, which also is what allows water to form droplets and soap bubbles to float.
The key to ultrasonic cleaning solutions is that surface tension is reduced in the cleaning tanks with a cleaning solution. This allows the small bubbles to hold more energy and also makes ultrasonic cleaning more effective.
Since the cleaning solutions, called surfactants, are designed to reduce surface tension instead of break chemical bonds, they are typically very mild and environmentally friendly.
Disposal of Solutions
Typically, ultrasonic cleaning baths and the solutions that are used in them are water based and environmentally friendly. While this isn’t the case for every cleaning solution, most are very easy to dispose of, as long as you consider the contaminants that are also being disposed.
Depending on the contaminant that you are cleaning, disposing of your cleaning solution may be difficult. Before disposing of your solutions, make sure that you check all of the contaminants so you are properly treating any environmental hazards.
How long can a solution sit on the shelf before it needs replacing? The quick answer is that it depends on the type of solution. Some solutions, like emulsifiers, are very powerful but have a very low lifespan because of quick oil saturation.
Other solutions, such as separating detergents, are much longer lived but they are not as effective at cleaning tough products.
As you can see, there is often a tradeoff when selecting what cleaning solution you would like to use. Omegasonic’s staff is very helpful and can work with you to determine the right balance of longevity and cleaning effectiveness.
Need Help Choosing the Right Ultrasonic Cleaning Solution?
A quick glance at the list of available ultrasonic cleaning solutions might have you confused as to which is the right one for you. Contact Omegasonic’s expert staff for help in getting the right solution for your cleaning needs.
One of the most important parts of your ultrasonic cleaner is the ultrasonic cleaning solution that you use. Ultrasonic cleaner solution is the medium that does the heavy lifting.
Solution composition and temperature are two of the things that can have an effect on the outcome of your cleanings.
Traditionally, solutions used in ultrasonic cleaning were made of some pretty nasty chemicals. Freon and trichloroethane were used to great effect in the process. With new green chemical regulations, specifically ones that target products like these organic compounds, solutions have been moving in an environmentally friendly direction.
There are now a wide variety of water based solutions available to use in your cleaning tank. Water is known as the universal solvent for a reason; it is excellent in the role.
It is hard to get more environmentally friendly than water. Water is also chemically inert, not poisonous and will not catch fire. The downside is, water which is considered contaminated can be hard to dispose of. Before using water based solutions for cleaning, make sure that you have a proper disposal plan in place.
To improve the performance of water, it is best to add detergents to the mix. This assists when you are attempting to rinse and dry already cleaned parts. Detergents also aid in loosening the bonds between the contaminate and the substrate you are trying to remove it from. They can also help to clean hard to reach areas that may not come clean with water alone.
The properties of water also allow it to compress more easily than organic solvents. This means you get more energy out of your tank than you would using other compounds.
Ultrasonic Cleaning Solution Temperature
Along with the type of solution that you are going to use, be very careful to monitor the temperature of the solution. There are a lot of things going on in the solution during cavitation that can cause unexpected and possibly even negative results.
Generally speaking the warmer the solution is, the better the cavitation results. The issue is when you start approaching the boiling point of the solution.
If we review some high school chemistry, you might remember that pressure can affect the boiling point. Even if you do not remember that, just look at the instructions for a package of noodles or rice at high altitudes. You will see at lower pressures, it is easier to boil water. What does this have to do with your ultrasonic cleaner?
What you are actually doing is creating little waves of energy in the solution. The front of the wave has increased pressure. This means at the back of the wave, there is decreased pressure. If the combination of the drop in pressure and the temperature of the solution exceed the boiling point of your solution, you can develop bubbles, reducing the effectiveness of your ultrasonic cleaner.
Omegasonics has a wide variety of ultrasonic cleaning solutions that cover any cleaning need you might have. Take a look and contact us today for your cleaning solution needs.
Next to the tank, the most important thing in ultrasonic cleaning is the solution. Over time, your ultrasonic cleaner solution can have a build up small gas bubbles in the liquid. These bubbles can cause problems with the operation of your ultrasonic cleaner.
Bubbles and Dissolved Gasses Make for Unwanted Partners
Ultrasonic cleaners work by creating waves in the tank. Think about a surface wave on a calm body of water; the high part of the wave inside the tank is a region of increased pressure.
The trough of the wave is a low pressure area. These low pressure areas will allow bubbles to form. When your ultrasonic cleaner solution has dissolved gasses in them, they will make their way into these low pressure areas.
Dissolved gasses in the low pressure areas will combine with the bubbles that are already there and make them increase in size. The larger bubbles will in turn start to absorb the smaller bubbles. This increases their surface area, creating larger air pockets in the solution.
Bubbles Act like Cushions
The way an ultrasonic cleaner works is by using very small bubbles to create a vibrating action to clean your item. If the large bubbles created from the dissolved gasses are allowed to form, they will create a barrier between the part you wish to be cleaned and vibrating bubbles.
This means that your cleaner will not be nearly as effective as it should be when operating at a particular temperature and frequency.
Along with the need to degas to increase cleaning effectiveness, you might also want to consider degassing in a few other cases:
- If you are measuring the size of cleaned off particulates, dissolved gasses can cause measurement errors
- Degassing lubricants can increase their effectiveness and reduce pump wear
How to Degas Your Ultrasonic Cleaner Solution
In order to degas your solution you will need the aid of a chemical additive. Degassing chemicals, called cleaning chemistry, will be added to the solution after you raise the temperature of the solution.
Degassing techniques work much better with your solution at a higher temperature. Remember to keep the temperature below the boiling point, as this will just add more gas to your solution.
Once you have raised the temperature, add your cleaning chemistry and begin to operate your ultrasonic cleaner. You will want to operate the cleaner for about 10 to 30 minutes. The time is mostly dependent on the size of your tank, as well as the amount of ultrasonic cleaner solution you are attempting to degas.
- Lower amplitudes work better for degassing
- A slight vacuum above the tank can assist in releasing gasses
- Avoid generating turbulence in the tank
Degassing can be an important step in not only keeping your cleaner running at top efficiency, but making sure you limit wear and tear on the unit. Omegasonics offers a wide range of cleaning products and ultrasonic cleaning devices. Contact us today!
In a previous article, we discussed the different types of contaminants that can be removed by various ultrasonic cleaning solutions. In this article, we’ll talk about the different types of materials that can be cleaned using these same solutions in our ultrasonic cleaners, and why choosing one over another may better suit our needs. Just as with contaminants, there may be more than one type of ultrasonic cleaning solution that may work with a particular material; final selection then will be based on the type of contaminant to be removed, as well as the relative speed or aggression with which we’d like the article cleaned. Even the finish of the part may affect our decision.
Prior to ultrasonic cleaners, many of the parts we needed to clean required harsh solvents that had safety and health risks associated with them, were harmful to the environment, and had to be treated as hazardous wastes when it came time to dispose of them. The ultrasonic cleaning solutions list presented here contains no such solvent-based cleaners. The detergents and cleaning agents used in ultrasonic cleaners are safe for our employees and safe for the environment.
Here is a generalized list of ultrasonic cleaning solutions, and the types of materials they clean effectively and safely:
Alkaline Solutions – Alkaline solutions have a pH of 10 or higher, with the higher pH solutions being more aggressive. They may or may not contain caustic soda, depending on the strength of the cleaner. Moderately alkaline solutions (pH 11.0 to 12.5) are great for almost all metals, including cast iron, steel, stainless steel, aluminum, zinc, copper, brass, and tin. They also work well when cleaning glass, ceramics, and most plastic materials.
High Caustic Solutions – High caustic solutions are a special case of alkaline solutions. They can be used if needed; however, we should always try more moderate alkaline ultrasonic cleaning solutions first. High caustic cleaners contain hydroxides and usually silicates as well, and are good for removing heavy grease, oils, and waxes from cast iron, steel, and stainless steel. When placing magnesium in our ultrasonic cleaners, a low caustic solution must be used if we are to avoid damaging the part.
Acidic Solutions – Acid-based solutions have a pH of around 5.0 or lower, with lower pH cleaners being the more aggressive versions. The use of acid solutions is usually material-specific, since some acids will destroy the base material while others will not. They are great for removing oxides from most metals, as long as the solution has inhibitors to protect the base metal.
Enzymatic Solutions – Enzymatic ultrasonic cleaning solutions are designed to remove protein-based contaminants from parts typically found in the medical and food industries. As such, they are typically used on stainless steel, titanium, brass, and aluminum, but can also be used on glass and most plastics found in laboratories.
De-ionized Water – DI water is safe to use on any material that can safely be placed in water, which means it will work on nearly every material. Metals, fabrics, glass, plastics, epoxies, and hard rubber materials are all acceptable. The type of part should be considered when DI water is used as an ultrasonic cleaning solution, since many parts will oxide quickly when removed from the solution unless they are subsequently placed in a wetting solution and immediately dried. Frictionless bearings, small servo motors, switches, and printed circuit boards are some examples of the parts requiring special post-cleaning treatment.
In addition to the general classes of ultrasonic cleaning solutions listed here, we need to remember that many also contain additives, such as sheeting agents, emulsifiers, and inhibitors, which perform special functions in the solution. The labels and product descriptions are accurate on these products, but it’s always best to test a small part first, or consult an ultrasonic cleaning consultant or the solution’s manufacturer to make sure we’re not making a decision that could adversely affect the part or the quality of the final cleaning. It’s always best to err on the side of caution, particularly with delicate or one-of-a-kind parts that may be difficult or impossible to replace. Regardless of the part or material, there’s almost always an appropriate ultrasonic cleaning solution that will safely remove contaminants from it.