How to Pick the Best Ultrasonic Cleaner

Selecting the Best Ultrasonic CleanerTips on Selecting the Best Ultrasonic Cleaner

So, you’ve landed here because you’ve heard about ultrasonic cleaning and how wondrous it works in removing almost any contaminant from almost any surface that can be immersed in an aqueous cleaning solution.  The task you have now is how to select the best ultrasonic cleaner for the cleaning challenges you have in mind. 

Here we offer some useful suggestions.

Why Selecting an Ultrasonic Cleaner is Important

If you’re interested in selecting an ultrasonic cleaner for your cleaning operations you’ve probably done a bit of research and found that choices seem endless.  The range of sizes, shapes, features and pricing is further complexified (our word) by prices for the units.  How do you select an ultrasonic cleaner and be assured that it will do the job you expect of it?  

This post does not get into pricing.  What we hope to do here is to give you guidelines on selecting the best ultrasonic cleaner based on your requirements.  We hope you’ll select from the many models available from Tovatech but that’s up to you.

A Brief on How Ultrasonic Cleaners Work

(Skip this if you already know how ultrasonic cleaners work and go to the following sections)

An ultrasonic cleaner includes a cleaning solution tank to which are affixed ultrasonic transducers that are powered by the unit’s ultrasonic generator.  The transducers are generally bonded under the tank bottom although some cleaners have them bonded to the sides.  There are also transducers that are immersed in the tank – sometimes called “shoebox” transducers. Wherever or however they are placed, their function is the same.

When activated transducers vibrate at their assigned frequency in kilohertz (KHz) causing the bottom of the tank to vibrate as a membrane and create billions of microscopic vacuum bubbles pulsing through the solution.  When the bubbles implode they release a powerful jet of liquid (the cleaning solution) to blast and carry away contaminants from products being cleaned.  The process is called ultrasonic cavitation.  

Getting Started on Selecting YOUR Ultrasonic Cleaner

Among the steps to be taken to select your best ultrasonic cleaner is a thorough understanding of what the process is to accomplish and then identify ultrasonic cleaner features that let you accomplish the task(s) in the most cost-effective way.  As we noted above ultrasonic cleaners are available from a variety of manufacturers and across a broad spectrum of prices.  But your investment must be based on an assurance that it will accomplish your task(s) quickly and efficiently.  When you do this you’ll be able to identify your best ultrasonic cleaner.  

 In other words, pick the ultrasonic cleaner you need.  Don’t succumb to “keeping up with the Joneses”  or trying to save a few bucks in hopes that “heck, it will do the job” (hopefully).

Suggested Ultrasonic Cleaner Selection Criteria

Size

You can’t mount a 19-inch tire on a 15-inch wheel.  Similarly the dimensions (length, width, depth) of the ultrasonic cleaner’s tank must be sufficient to accommodate the largest component you plan to clean.

But there’s more:  Because a majority of ultrasonic cleaning cycles take place when parts are in a basket, the basket size becomes the determining factor.  Whether standard or an optional item, basket dimensions are slightly less than tank dimensions. 

A related concern is what is called the working depth of the unit, which is the distance between the bottom of the basket and the surface of the cleaning solution.   Whatever you clean should be fully immersed in the cleaning solution.

If product literature does not provide this critical information ask the manufacturer.

Ultrasonic Frequency

A majority of ultrasonic cleaning operations are accomplished with equipment operating within a range of 37 to 45 kHz.  Equipment is available to operate at lower or higher frequencies.

Ultrasonic frequencies determine the size of cavitation bubbles that do the cleaning job.  Lower frequencies are better for heavily soiled cast or fabricated materials, higher frequencies work best for delicate parts or those with soft or highly polished surfaces.  Cleaners are also available operating at dual frequencies to extend their utility.

Ultrasonic cleaner size and ultrasonic frequency are two important points to resolve as you set about picking your best ultrasonic cleaner.   Before we provide specific product suggestions we’ll offer this checklist of operating features beyond on-off switches that can contribute to the efficiency and thoroughness of your ultrasonic cleaning operations.  

Picking Ultrasonic Cleaner Operating Features

Your wisest ultrasonic cleaner purchase may be a simple on-off unit.  But more than likely it will be enhanced with a series of operating features available from manufacturers such as Elma, available from Tovatech.  Here is a representative checklist from which to choose:

  • Timers let you set the length of the recommended cleaning cycle length (often suggested by cleaning solution manufacturers and your personal user experience). When cleaning begins start the timer and attend to other matters. The unit will turn off at the end of the cycle. Time cycles depend on models. 
  • Temperature controls – thermostats – let you set the recommended cleaning temperature, also suggested by solution manufacturers (and your experience). Some equipment will automatically start the ultrasonic cleaning cycle when the set temperature is reached.
  • A sweep mode is a slight ± variation in ultrasonic frequency to provide more uniform cleaning and avoid damage to delicate electronics and highly finished surfaces. The normal mode operating at a fixed frequency is useful for sample prep in labs
  • A degas mode speeds the removal of trapped air in fresh cleaning solutions that otherwise impedes cleaning action. Degassing can also be achieved by operating the unit for a period of time without a load.
  • A manually activated pulse mode delivers intermittent spikes of very high ultrasonic power to remove stubborn contaminants. Pulse can also be used to degas the solution.
  • Adjustable power is a very useful feature because it allows you to tailor the cleaning cycle to the characteristics of products being cleaned. This feature enables you to clean a wider variety of products.
  • Dual-frequency ultrasonic cleaners also enable you to broaden the range of products that can be cleaned or prepared in the unit.
  • Parts agitation is a proven method of improving cleaning efficiency. While it can be done manually in smaller units, industrial ultrasonic cleaners can be ordered to provide gentle vertical ± 2cm oscillation to achieve a 10-20% increase in efficiency.
  • Cleaning solution maintenance features may be available on large ultrasonic cleaners. Examples include weirs and spray bars that direct floating contaminants into a collection container for later disposal, and pump-and-filter systems to remove contaminants in the solution.  Tip: Manually removing floating contaminants from smaller units prolongs solution life.

Examples of “Best” Ultrasonic Cleaners

As suggested above the best ultrasonic cleaner is the equipment that meets your cleaning requirements in the most cost-effective manner.   We present here examples of various Elma ultrasonic cleaning models widely accepted worldwide and available from Tovatech.  

Descriptions are not complete, and units are available in several cleaning solution capacities and tank dimensions.

Elmasonic E Plus Line  

The recently introduced  Elmasonic E Plus line of 37 kHz benchtop ultrasonic cleaners has an operator-activated pulse control that boosts power up to 20% to remove stubborn contaminants, degas solvents and to mix, disperse and dissolve lab samples.  A permanent sweep function ensures even distribution of cleaning action throughout the bath.  The choice of sweep and pulse functions addresses the full range of ultrasonic unit applications for parts cleaning and for applications in scientific and medical laboratories.  The units are equipped with a heater and timer.

Elmasonic S Line Cleaners

The 37 kHz Elmasonic S line operates in the sweep, degas and normal mode and automatically adjusts power to the nature of the load.   The S150 model is especially designed for sample prep in the lab due to its shallow depth that enables it to deliver an average ultrasonic power of 300 watts to quickly process difficult samples and do double duty as an ultrasonic cleaner for instruments and glassware.  Another specialize unit is the S50R sonicator that performs sample prep, solvent degassing, instrument cleaning and sieve cleaning.

Dual-Frequency Elmasonic P Line Cleaners

As noted earlier, dual-frequency ultrasonic cleaners support a broader range of applications allowing users to expand their services.  The Elma P line operates at 37 kHz for normal cleaning tasks or 80 kHz for sensitive surfaces or delicate products such as spectrophotometer cuvettes.  It can also be set to alternate between the two frequencies at 30-second intervals.  It operates in the normal, pulse, sweep and degas modes, is equipped with a heater and timer, and has a higher average and peak power than any unit on the market.  Power is fully adjustable so users can set cleaning intensity.

Industrial Ultrasonic Cleaners

Benchtop industrial cleaners are exemplified by the Elma TI-H series available in two, dual-frequency models:  25/45 and 35/130 kHz, both offering stepless power control increments from 10% to 100% of their full ultrasonic power. 

Floor model and custom industrial ultrasonic cleaners are also available and exemplified by the Elma xtra ST, xtra Basic Flex 1 and Flex 2, and Tova Pro units. 

Cleaning with Volatile Solvents

Flammable solvents such as acetone, IPA, MEK and toluene are often employed when cleaning products that that are sensitive to water or require the absence of residues.

Special procedures and/or equipment are required when using flammable solvents.  Tovatech offers five options that may solve your challenges that involve cleaning with volatile solvents.

In Conclusion

This post covers many but not all considerations on selecting the best ultrasonic cleaner to meet your requirements.  Equipment is but part of the selection process.  Cleaning solution chemistry also plays an important role.  For an introduction we invite you to read our post on cleaning solution selection guidelines. For other information please visit our ultrasonic cleaning learning center tutorial on ultrasonic cleaners

Please call the scientists at Tovatech for unbiased help in selecting equipment, cleaning solution formulations and operating procedures that will help you do the job quickly and efficiently.

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About Rachel Kohn

So how did an MIT Ph.D. end up selling refrigerators? When I figured out that a lot more scientists buy lab refrigerators than innovative leading-edge instruments. I hope that my many years of lab experience will help you find the right equipment for your work. Before co-founding Tovatech I worked in business development and project management at Smiths Detection, Photon-X, Cardinal Health, and Hoechst Celanese. And before that I spent 12 years as an R&D chemist at Hoechst Celanese and Aventis working on advanced drug delivery systems, polymer films and membranes, optical disks, and polysaccharides. Some day, eventually, I’ll make enough money to develop an innovative technology that will change the world.

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