Multifrequence
Why Multifrequency in Ultrasonic Cleaning?
Multifrequency ultrasonics in MOG MORONI generators.
Multifrequency ultrasound deserves a separate and in-depth discussion.
Particle Size
In the light of tests carried out in the laboratory over many years and as reported in all the specialized literature it is now established that the particles of dirt particles are of great importance in determining the frequency of the ultrasound wave more suitable for their removal.
Especially:
- high frequencies work better on fine particles.
- medium-to-low frequencies shatter particles faster.
Erosion
The wavelength (which is the reverse of the frequency) determines the wings and nodes of less or greater cavitation intensity. If the nodes remain fixed at the same time with the time the material to be washed is eroded but even more the tank itself (cavitation).
For this reason, it is indispensable to continuously vary the working frequency to move the node’s volume to the entire volume and eliminate them. For the swirl that is created. it is also obtained that the result of the washing uniforms throughout the surface of the parts to be treated.
Stationary Waves
When energy is injected into a liquid it must be borne in mind that this by inertia and reaction tends to support the movement and therefore to attenuate the impact energy, that is, it generates stationary waves (spurs) that subtract a considerable part of the energy initial. For impeding the training, the wave of the energy insert does not must have a constant frequency, also must be various and very if for infinitially periods.
To this end two techniques are adopted:
- variation (brushing or sweeping) “cycle per cycle”
- the simultaneous generation of different frequency waves (multiplexers):
Together with the carrier energy, waves with different frequencies are introduced, within an adjustable period through setting software. Naturally, the frequency choice is not casual, but is depended by the characteristics of the PZT elements that more than the frequency of resourcing may operate to the top harmonization frequencies, but with a minimum power.
For the aforementioned reasons, multifrequency generators have been set up in the last few years: they operate thanks to the 32-bit logic of recent high-speed production, so that they pass from one frequency to the other in infinitesimal times, that is, in practice at the same time.
Summing up, with multi-frequency generators, the following advantages are:
- removal of particles of any size
- attenuation of erosion on tanks, transducers, and workpieces to be treated
- greater power available due to the elimination of spurious or stationary waves
- Immediate degassing of the washing liquid (see below under “degassing”)
The MOG MORONI generators have the dual chance of working in multifrequency with sweep or multiplexer technology.
