ICT
TECHNOLOGY OVERVIEW
Ultrasonic Cleaning EFFICIENT CLEANING WITH ULTRASOUND FROM COARSE TO FINE
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cohesive forces are overcome. This causes the formation here’s hardly a company today that can do without parts of millions of microscopically small bubbles. During the and surface cleaning. This work step can be executed subsequent pushing phase, these cavitation bubbles are in an extremely effective, economic and ecological fashion rendered unstable and collapse (implode), and they generate with ultrasound in numerous manufacturing applications, hydraulic impacts with considerably high energy densities, as well as in the field of MRO. Regardless of whether coarse contamination needs to be removed, or highly sensitive, finely thus causing micro-currents in the liquid. When these strike a surface, they blast off contamination which has been structured parts have to be cleaned. partially dissolved with a suitable cleaning agent and rinse Ultrasound technology has only been in commercial use the “dirt” away. for about 100 years. It was sparked off by the sinking of Ultrasound is rendered effective due to the fact that the Titanic after it collided with an iceberg. This led to the cavitation occurs at boundary surfaces – precisely development of an ultrasonically supported where contamination tends to positioning system for maritime adhere to the surface. This traffic. A great variety of cleaning effect is also other applications for known as “microthe use of sound scrubbing” or waves evolved “electronic thereafter, brushing”. amongst others And ultrasonic ultrasonic cleaning is just cleaning. as thorough Its mode of as it is gentle, operation because the allows for effects of efficient, cavitation – environmentally when applied for sound removal a short time only – of particulates and leave even sensitive film-like contamination, surfaces unscathed. which is also gentle Image source: Bandelin on the material to be 1 cleaned, for tasks in Ideal Oscillation Due to the great intensity of the alternating sound pressure during the pulling phase of the oscillation cycle, the liquid is broken up during exposure of the cleaning bath to ultrasonic waves. manufacturing, as well The sound waves are Cavitation bubbles are formed as a result. as in MRO – even for produced by means parts with difficult to of a generator which access hollow spaces, for example blind holes, knurling and converts the normal electrical mains frequency of 50 to 60 grooves. Complete sub-assemblies, for example gear units, no Hz into high-frequency oscillation. This electromagnetic longer need to be dismantled for cleaning. oscillation is then transformed into mechanical oscillation of the same frequency by so-called sonic transducers. The dimensions of the oscillator are decisive with regard to Micro Scrubbing based on Liquid Currents the working frequency. Ultrasonic waves develop their full cleaning effectiveness The sound waves spread longitudinally through the cleaning in a liquid bath. The cleaning effect is based on cavitation: bath. This results in aphonic and phonic zones. Ultrasonic When a liquid is subjected to ultrasonic sound, the high intensity of the alternating sound pressure during the pulling oscillation can be more evenly distributed in the cleaning liquid with the help of frequency modulation (sweep function). phase of the oscillation cycle breaks up the liquid – the
28 AUGUST 2011