Key Guidelines Pertaining to Ultrasonic Cleaning Equipment and Process Performance W hile there are few specific rules for benchmarking the performance of an ultrasonic sys- tem, there are some general consid- erations regarding the overall need for a new system, or evaluating the day-to-day performance of your present system. Following are some general guide- lines about ultrasonic cleaning equipment and performance: How do I know when it’s time to advance to ultrasonic cleaning? If you are evaluating whether to switch to ultrasonic cleaning, you also need to evaluate how you are cleaning the item(s) in-question now, and what are the results. Results can be measured in terms of the labor, time and cleanliness of the workpieces you are cleaning now. It can also be measured in terms of safety— the risk via expo- sure to solvents and other harsh chemicals that may be harmful to workers and the environment. In a majority of instances, ultra- sonic cleaning is much more effi- cient and cost-effective than manu- al cleaning or other methods of degreasing. Frank Pedeflous, of Simi Valley, Calif.–based Omegasonics, recounts a recent instance when his firm performed a comparison for a bottler who had an employee working solely on cleaning filler valves with a power- ful acid. This manual work required him to suit-up and wear heavy gloves to clean the valves with a brush. Because there were so many of these relatively intricate valves to clean, the man put in extensive overtime. “We brought in an ultrasonic unit and proved that the task could be accomplished better, much quicker and with no exposure to the caustic solvent,” Pedeflous explained. “It not only made good economic sense, but it also removed a safety issue.” How do I know what size ultra- sonic cleaner is best for my oper- ation? Pedeflous advises those who are thinking of purchasing ultrasonic systems—either for the first time, or an additional unit—to talk with sup- pliers who carry a full range of equip- ment sizes and models. “In many instances, an opera- tion can do fine with a tabletop model at one or more loca- tions. That gives them production flexibility,” Pedeflous said. “In other applications, feature–rich models with capabilities such as ‘set-and-forget’ tanks may help boost productivity.” In terms of applications, ultrasonic cleaning systems are used to cleanse or sanitize a wide variety of items that are sometimes intricate, require precision or are delicate, such as jew- elry or surgical instruments. Of course, the technology is also highly effective in cleaning more robust items such as components used in automotive, marine, aerospace, and other industrial applications. Why aren’t my workpieces getting as clean today as they did yesterday? “The usual answer to that question is: Something has changed,” Pedeflous said. The change, however, is not always found at the cleaning station, he adds. Once temperature, chemical concentration and all other cleaning parameters have been ruled out, the search should proceed to consider changes in the manufac- turing steps. Common sources of problems include changes in lubricants, manufacturing processes, and even raw materials. TECHNICALLY speaking BY OMEGASONICS, SIMI VALLEY, CALIF. 24 I metalfinishing I July/August 2011 www.metalfinishing.com
While there are few specificrules for benchmarking the
performance of an ultrasonic sys-tem, there are some general consid-erations regarding the overall needfor a new system, or evaluating theday-to-day performance of yourpresent system.
Following are some general guide-lines about ultrasonic cleaningequipment and performance:
How do I know when it’s time toadvance to ultrasonic cleaning?
If you are evaluating whether toswitch to ultrasonic cleaning, youalso need to evaluate how you arecleaning the item(s) in-questionnow, and what are the results.Results can be measured in terms ofthe labor, time and cleanliness ofthe workpieces you are cleaningnow. It can also be measured interms of safety— the risk via expo-sure to solvents and other harshchemicals that may be harmful toworkers and the environment.
In a majority of instances, ultra-sonic cleaning is much more effi-cient and cost-effective than manu-al cleaning or other methods ofdegreasing. Frank Pedeflous, ofSimi Valley, Calif.–basedOmegasonics, recounts a recentinstance when his firm performed acomparison for a bottler who hadan employee working solely oncleaning filler valves with a power-ful acid. This manual work requiredhim to suit-up and wear heavygloves to clean the valves with abrush. Because there were so many
of these relatively intricate valves toclean, the man put in extensiveovertime.
“We brought in an ultrasonic unitand proved that the task could beaccomplished better, much quickerand with no exposure to the causticsolvent,” Pedeflous explained. “It notonly made good economic sense, butit also removed a safety issue.”
How do I know what size ultra-sonic cleaner is best for my oper-ation?Pedeflous advises those who arethinking of purchasing ultrasonicsystems—either for the first time, oran additional unit—to talk with sup-pliers who carry a full range of equip-ment sizesand models.
“In manyinstances,an opera-tion can dofine with a
tabletop model at one or more loca-tions. That gives them productionflexibility,” Pedeflous said. “Inother applications, feature–richmodels with capabilities such as‘set-and-forget’ tanks may helpboost productivity.”
In terms of applications, ultrasoniccleaning systems are used to cleanseor sanitize a wide variety of itemsthat are sometimes intricate, requireprecision or are delicate, such as jew-elry or surgical instruments. Ofcourse, the technology is also highlyeffective in cleaning more robustitems such as components used inautomotive, marine, aerospace, andother industrial applications.
Why aren’t my workpieces getting as clean today as they did yesterday?“The usual answer to that questionis: Something has changed,”Pedeflous said. The change, however,is not always found at the cleaningstation, he adds. Once temperature,chemical concentration and all othercleaning parameters have been ruledout, the search should proceed to
consider changes in the manufac-turing steps. Common sources ofproblems includechanges in lubricants,m a n u f a c t u r i n gprocesses, and evenraw materials.
TECHNICALLYspeaking
BY OMEGASONICS, SIMI VALLEY, CALIF.
24 I metalfinishing I July/August 2011 www.metalfinishing.com
www.metalfinishing.com July/August 2011 I metalfinishing I 25
required for effective cleaning.” On the other hand, too much
ultrasonic power may result in cavi-tation erosion occurring on delicateor highly polished parts that are nearthe transducer-radiating surface.(Cavitation is the formation and col-lapse of low-pressure bubbles thatcan pit the surface of metals.)Aluminum, copper, brass and othersoft metals are especially susceptibleto cavitation erosion.
What is “degassing” and why is itimportant?Degassing is the process of removingsmall, suspended gas bubbles anddissolved gas from a liquid prior tousing it for ultrasonic cleaning.
“Unless you remove the dissolvedgas, it can migrate into cavitation-bubbles during their formation,”Pedeflous stated. “This prevents thebubbles from imploding correctly,which reduces the cleaning effect.Also, the gas bubbles will absorbultrasonic energy, reducing the ultra-sound cleansing intensity inside thetank.”
Liquids should be degassed by rais-ing the temperature, adding thecleaning chemistry, and operatingthe ultrasonic energy for a period of
Clogged filters, misdirected coolantnozzles and improper machining orfinishing practices may also causeultrasonic cleaning problems.Remember, a change that may beconsidered inconsequential to themanufacturing process might resultin less effective cleaning—until thenecessary adjustments are made.
How much ultrasonic power doesyour cleaning tank require?The right amount of ultrasonic ener-gy (usually expressed in watts/gal-lon) depends on the size of the clean-ing bath and the difficulty of thecleaning requirement. Tanks in the1- to 2-gallon range often provide upto 90 watts per gallon of ultrasonicpower, plenty for most jobs, evencleaning out the ultra-fine passagesof fuel injector nozzles.
“Achieving the same cleaning effectin larger tanks requires less energydensity,” Pedeflous advises.“Excellent cleaning has been demon-strated in tanks having 50 gallonscapacity with only 25–30 watts pergallon. The more difficult the appli-cation, the greater energy density is
time ranging from 10 to 15 minutesminimum (depending on the size ofthe tank and the nature and concen-tration of the chemicals being used)prior to use. When completelydegassed, small bubbles will not beseen rising to the liquid surface dur-ing ultrasonic operation.
Will ultrasonic cleaning damageelectrical components?If you regularly clean electronicparts, an ultrasonic electronics clean-er is the best tool for the job. Thecommon concern is that ultrasoniccleaners will destroy delicate compo-nents. However, advances in ultra-sonic technology have eased this con-cern by replacing the single frequen-cy wavelength approach—known toharm electronic parts—with a vari-able frequency approach, called“sweeping.” This advance in ultra-sonic technology has not only led toreduced production costs, but hasproven to enhance reliability andreduce warranty costs as well.
As Pedeflous explains: When elec-tronic parts are immersed in anultrasonic cleaner, cleaning occurswherever the liquid makes contactwith the parts. Higher ultrasonic fre-quency can penetrate smaller open-ings and remove tinier particles.Since the liquid reaches into smallcrevices and cavities that are impossi-ble to clean manually, ultrasoniccleaning electrical assemblies andelectronic components is an idealapproach. Furthermore, today’sadvanced ultrasonic cleaning equip-ment is designed to prevent “part res-onance”—the internal agitation ofparts due to recurring harmonicvibrations—that otherwise mightdamage more sensitive items.
For more information call FrankPedeflous at Omegasonics at (805) 583-0875, write at 330 E East St #A SimiValley, CA 93065-7523, e-mail:[email protected], or visitwww.omegasonics.com.
TECHNICALLYspeaking
For many applications, ultrasonic cleaning can cut down on costs, while at the same time produceparts that not only look and perform better but also require less frequent subsequent cleaning.
