Frequently Asked Questions About Ultrasonics

Do higher frequency ultrasonics penetrate smaller openings better than low frequency ultrasonics?

Are Piezoelectric transducers more efficient that Magnetostrictive transducers?

Does high power, low frequency ultrasonics damage delicate parts?

Are sweep or multi frequency designs better to eliminate the problems of standing waves?

What is the squeal I occasionally hear from my cleaning tank?

Will ultrasonics clean blind holes and small diameter holes?

Why does my ultrasonic cleaner seem to clean good and then start to decline in performance?

Does the shape of the tank or position of the ultrasonics matter?

Why canít I get parts in my plastic carriers as clean as parts in my metal ones?

Should ultrasonics be used in rinse tanks to continue cleaning?

 

Q: Do higher frequency ultrasonics penetrate smaller openings better than low frequency ultrasonics?

A: The higher the frequency, the smaller the bubbles for cavitation and correspondingly the lower the power to be released. The misconception is that the smaller bubble will ìfitì into smaller openings than lower frequency bubbles. In fact, the cavitation bubble is formed each half cycle where the void is located and implodes there also. So the cavitation bubble actually forms to the shape/hole/space that exists on the part. Therefore, low frequency ultrasonics will ìfitî in the smallest spaces. Also, the higher power actually will form bubbles in areas that lower power cavitation cannot because it takes more power to reach difficult spaces. Therefore higher power is more effective. top

Q: Are Piezoelectric transducers more efficient that Magnetostrictive transducers?

A: Piezoelectric materials that make up the elements are more efficient materials in energy conversion than magnetostrictive materials. The more important question is the efficiency of the entire transducer assembly and its efficiency generating cavitation energy in the bath. In that, both materials produce about the same efficiency at the radiating surface. Piezoelectric elements are small individually powered units bonded individually to the radiating plate and functional independently from each other. That results in open areas of the radiating surface not being actively driven by an element. In addition, since they move independently, the radiating surface does not necessary move as one unit. W3 design magnetostrictive materials are laminations bonded across the entire radiating face and powered as a unit which produces a 'piston' effect. That synergistic force produces much more cavitation force in the bath for the same power input ultimately making it more efficient than piezoelectric designs. top

Q: Does high power, low frequency ultrasonics damage delicate parts?

A: Any ultrasonics can damage delicate parts if improperly applied. Improperly applied, high power, low frequency can do more damage to more parts because it generates more cavitation energy in the bath. The mistake that leads to damaged parts and cavitation erosion of vulnerable surfaces is time. Low power ultrasonics requires more time to clean so to clean the entire part load, the parts remain in the bath to get all parts clean. Therefore, a clean, exposed part surface may see more direct cavitation and regardless of the power, cavitation erosion results. So the real answer is to intelligently apply the maximum amount of ultrasonic power for the shortest amount of time in the least aggressive chemistry. top

Q: Are sweep or multi frequency designs better to eliminate the problems of standing waves?

A: Standing waves are a reality of the phenomenon of ultrasonics. Sweep and multi-frequency designs and other alterations diminish or move standing waves but they are never eliminated. Actually, the standing wave is where the power exists that allows you to clean, therefore as the waves are diminished, so is power. Still, W3 also manipulates standing waves with the power input to either minimize or actually maximize standing waves depending on the application. Proper application of the parts load, parts handling, tank design and power control can result in any ultrasonics being able to maximize cavitation without any problem with standing waves. top

Q: What is the squeal I occasionally hear from my cleaning tank?

A: The squeal is air entrapped in a bath that has not been fully degassed. It is most common when a fresh cleaning bath has been mixed. Or it happen in a degassed bath that has set idle for some time and air molecules have started to re-enter the bath. Rapid movement of the part load can also produce the squeal. Sometimes a chemistry that does not support cavitation will also create the squeal. Proper set up with correct chemistry, correct temperature, ultrasonic power only with a load in the bath and slower motion should eliminate all squeals. top

Q: Will ultrasonics clean blind holes and small diameter holes?

A: Absolutely. Ultrasonics is the only way to do that. However, the part must be oriented properly to allow trapped air to be replaced with bath solution. Experienced application with regard to the load orientation will make cleaning tight clearances, even blind ones, easy. top

Q: Why does my ultrasonic cleaner seem to clean good and then start to decline in performance?

A: Something changed. The best practice is to keep a log on all aspects of the process and the machine. That makes it easy to retrace and find the reason. Without a log, check and clear the equipment for proper operation and then begin changing one, and only, variable in the process at a time until successful. It is seldom the equipment and generally an element of the process, sometimes more than one, if the cleaning function has been unattended for some time. top

Q: Does the shape of the tank or position of the ultrasonics matter?

A: Ultrasonic power starts out at the transducer as a perpendicular uni-directional wave with maximum cavitation action directly in front of the radiating surface of the transducer. We refer to that as primary cavitation energy. The amount of power of the sound wave generated into the solution increases the resultant cavitation energy released. Reflection and other disbursement of a high energy sound wave can effectively cause ultrasonic power to become omni-directional resulting in good cleaning in other areas of the bath. We refer to that as secondary cavitation energy. W3 has a revolutionary new product line called Surround that actually uses tank shape to enhance cleaning effectiveness of both primary and secondary cavitation. top

Q: Why can't I get parts in my plastic carriers as clean as parts in my metal ones?

A: Cavitation requires a hard surface to be most effective. Soft materials absorb the cavitation implosion scrubbing effect and reduce power. Hard plastics can support effective cavitation as well as metals. One factor with some plastics is, what might be called, static cling. That can be a real nuisance. top

Q: Should ultrasonics be used in rinse tanks to continue cleaning?

A: In a word, no! The rinse operation is for rinsing dirty solution, not cleaning primary dirt. If you still have dirt remaining on the part, then the washing stage is not doing the job, the rinse tank will go south fast and soon dirty parts will emerge. Using ultrasonics in the rinse stage though is good practice if the part configuration dictates it. The cleaning process is simple. Wash in the wash. Rinse in the rinse. Dry in the dry. top

 

 

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