Ultrasonic Solution Selection Guidelines
“Solution” has two definitions: A liquid mixture and solving a problem.
Not coincidentally, two points apply when seeking desired ultrasonic parts cleaner solution for parts cleaning results. These are (1) a liquid mixture called an ultrasonic solution, chemical or soap, and (2) the ultrasonic parts cleaner equipment. Putting it another way, satisfactory ultrasonic solution results most likely occur when you select chemicals and equipment to solve the problem – the cleaning job – at hand.
These ultrasonic solution guidelines take you through the two points.
The Ultrasonic Solution as a Chemical
These are specially formulated to accomplish specific ultrasonic cleaning challenges.
Most ultrasonic solutions are available as concentrates and are biodegradable. These two features contribute to economy and reduce disposal concerns.
Regardless of the chemistry, an ultrasonic solution works by a process called cavitation. Details are found in our post Ultrasonic Cleaner Uses in Business and Industry.
A Closer Look at Ultrasonic Cleaner Solution Chemistry – What is pH?
What is pH? Wikipedia defines pH as a measure of hydrogen ion concentration; a measure of the acidity or alkalinity of a solution.
Although there are exceptions, ultrasonic cleaner solutions can be divided into three basic chemistries based on their pH: alkaline, acidic and neutral. Aqueous solutions at 25°C (77⁰F) with a pH less than seven are acidic, while those with a pH greater than seven are basic or alkaline.
The following paragraphs provide selected examples of ultrasonic solution chemistries and application examples. Tovatech scientists will provide recommendations to satisfy your particular requirements.
Acidic Ultrasonic Solutions
Acidic solutions remove corrosion and lime deposits, water damage, grease, oil and oxide layers from non-ferrous and light metals as well as PCBs, glass, plastics, tarnished brass and copper.
Stronger acidic solutions are also available for these materials along with nonferrous heavy metals, stainless steel, and cast iron.
Acidic cleaning solutions are exemplified by elma tec clean S1 with a pH of 1.6 in concentrate form. Recommended dilution is to 1 to 5% with water.
An important caution: Stainless steel ultrasonic cleaner solution tanks must be protected when using corrosive low pH solutions such as nitric, sulfuric, formic, or hydrofluoric acid. This is accomplished by using an acid resistant tub (offered in several sizes) along with other precautions described in our post on safely cleaning with acid.
Alkaline Ultrasonic Cleaner Solutions
A popular alkaline cleaning solutions is elma tec clean A4 with a pH of 13.4. It is widely used in labs and workshops. Diluted to 1 to 5% with water it removes grease, oils, soot, wax, combustion residues, and organic contaminants from engine parts, all metals, glass, ceramics, plastics and rubber.
A slightly milder alkaline formula is elma tec clean A1 with a pH of 10.8. Use it for removing light oils, fluxing agents, dust, grease and fingerprints from PCBs, electromechanical devices, electronics and fine optics. Recommended dilutions are to 3 to 10% with water.
Ammonia-containing elma tec clean A2 is an alkaline solution used to remove grinding, polishing and lapping media, grease and oil from nonferrous metals, precious metals, brass and copper. Its ammonia content leaves a bright shiny surface on brass and copper products. With a pH of 11, it is diluted to 5 to 10% with water.
When to Select a Neutral Ultrasonic Solution
An example of a neutral cleaning solution is elma tec clean N10 with a pH of 7.1 diluted to 2% with water. It is used to remove emulsions, residues of markings and labels, lime soaps, light greases and oils, fingerprints and dust from medical instruments and labware.
Another example of a neutral cleaning solution formulation is foam-inhibited elma clean 260 dip & splash that can be used either in an ultrasonic bath diluted to 2%, or for spray cleaning (1%) with tap or deionized water.
This formula is suitable for metallic surfaces including aluminum and light metal alloys as well as for glassy, ceramic and mineral surfaces. It removes aqueous cooling emulsions from mechanical treatments, deposited lime soaps and other contaminants.
Rust Protection
Surfaces subject to rusting should include elma KS in the cleaning or rinsing tank for temporary corrosion resistance.
Emulsifying and Demulsifying Ultrasonic Solutions
This distinction deals with what happens to the contaminants, particularly greasy contaminants, as they are removed by the cleaning process.
Demulsifying ultrasonic cleaner solutions cause oily contaminants to float to the surface of the cleaning solution. This makes them easy to skim off either manually or via spray bars and weirs for storage and later disposal.
The process reduces the potential for floating contaminants to adhere to the product while being removed from the bath and helps prolong the useful life of the ultrasonic solution. Demulsifying formulations are typically used in high-volume cleaning operations.
Emulsifying cleaning formulations hold contaminants in suspension and are used for low-volume cleaning operations.
Because contaminants remain in the solution rather than float to the top they build up over repeated cleaning cycles. In doing so they inhibit cleaning efficiency and, perhaps more important, may remain on the surfaces of cleaned products. This could necessitate post-cleaning rinsing operations.
With either formulation, hard particles such as chips, fines, shavings and plain old dirt fall to the bottom of the cleaning tank. These must be removed each time the solution is changed, otherwise they can damage the tank bottom.
Ultrasonic Solutions as Equipment
Benchtop Ultrasonic Parts Cleaner Solutions
Benchtop ultrasonic parts cleaners are offered in several models.
An economical choice for the shop or lab is the Elmasonic E Plus line. Available in 9 tank sizes from 0.25 to 7.5 gallons, it offers a Dynamic mode for powerful cleaning, to degas fresh cleaning solutions or to mix, dissolve and disperse samples. An Eco mode provides gentle cleaning of sensitive parts. Sweep frequency with power tracking assures consistent uniform cleaning.
Additional features are offered in the Elmasonic Select line in 11 tank sizes from 0.7 to 23.5 gallons. It offers 5 ultrasonic modes to optimize parts cleaning, sample preparation, and solvent degassing. Operators can save 4 programs for quick call up and reproducible results. The extra large digital display keeps track of the cleaning cycle and signals when it is completed.
Total control of the ultrasonic cleaning process, including frequency, power level, time, temperature, and ultrasonic mode is offered by the dual frequency 37/80 kHz Elmasonic P line in 6 tank sizes from 0.8 to 7.5 gallons. The P line has higher average and peak ultrasonic power than any ultrasonic bath on the market. Select from 4 ultrasonic modes for cleaning, intense cleaning, dissolving and degassing.
For heavy-duty ultrasonic parts cleaning with a benchtop unit, we recommend the Elmasonic xtra TT units in 4 tank sizes from 0.79 to 4.8 gallons. These units are designed to operate continuously up to 8 hours. They feature continuous Sweep for uniform cleaning and a dynamic mode to remove tenacious contaminants with boost of extra power.
Large Ultrasonic Parts Cleaner Solutions
Tovatech offers a wide selection of floor mounted large ultrasonic parts cleaners. These are floor-mounted mobile units offering multiple features best explained in our post large ultrasonic cleaner specification tips. The post provides useful guidelines on what to look for in these ultrasonic cleaners and links to applications where they are put to use.
Ultrasonic Cleaning using Volatile Solvents
In certain instances a volatile solvent such as IPA, acetone or toluene is recommended for ultrasonic cleaning operations.
IPA, for example, is used for cleaning medical instruments and surgical implants; acetone is a great solvent for degreasing and cleaning, both for the same reasons: they do not leave solution residues on parts being cleaned.
Requirements for cleaning with volatile solvents include the use of explosion proof ultrasonic cleaners located in an area where there are no ignition triggers from nearby electrical systems. When operating an explosion-proof ultrasonic cleaner you create what is called a National Electric Code hazardous location due to fumes given off and the possibility of spilled solvent.
If your operations require cleaning with volatile solvents contact Tovatech for information on the SOL-XP explosion-proof ultrasonic cleaner or other options along with information on how to comply with NFPA and related codes concerning hazardous areas. We also invite you to check out our post on cleaning with flammable solvents.
Post-Cleaning Points to Consider
Products that are painted, plated or powder coated are prime candidates for thorough post cleaning rinsing to ensure proper adhesion of the coating to the surface.
Post-cleaning rinsing steps can include washing with a water spray and immersion in an ultrasonic rinsing tank. These are used to flush away any residuals remaining due to what is called “drag out.”
In such cases, consider the Elmasonic xtra ST ultrasonic system with the hand-held rinsing option using either tap or demineralized water. There are customized units that can include cleaning and rinsing tanks followed by dryers.
Ultrasonic Solutions at Work
Here are a few examples of contaminants removed by ultrasonic parts cleaner solutions:
- grease, grime and grit on engine and drive train components
- mold support from 3-D printed products
- salt and other residues on scuba gear
- free iron and other contaminants on stainless steel (passivation)
- contaminants on new and reconditioned printed circuit boards
- burned on deposits on plastic injection molds
- finger marks and grime on cherished vinyl LP records
- contaminants on surgical and dental instruments
- oil and residues on finely machined parts
- contaminants on laboratory glassware and instruments
- tarnish or old paint on brass, copper and other surfaces
- powder residues and other contaminants on firearms
A Wrap-up on Ultrasonic Cleaning Solutions
We’ve touched on but a few examples on ultrasonic solution selection.
Contact Tovatech’s scientists for unbiased help in selecting the correct chemistries and equipment to efficiently accomplish your tasks.
