To establish this, you need to ask yourself a question: ‘Could I clean everything in my house with one brush’? You instinctively know that you couldn’t. Or, ‘Could I wash all of my clothes in my washing machine on the same programme’? Again, you know the answer is of course, no.
You wouldn’t take the risk of damaging your delicate clothes or household items so, why would you take such a risk with your stable of delicate, expensive anilox rolls?
Ultrasound, when applied into a tank of fluid acts just like a brush and there are 3 basic elements that go into determining the make-up of that particular brush. These are: POWER, FREQUENCY and MODULATION, where the power would represent the number of bristles, the frequency would represent the stiffness of the bristles and the modulation would represent the movement of the brush across the surface of the item being cleaned. All of these elements are important, but it is the width of the modulation or frequency sweep that mostly determines the safety aspect of the system.
The wider the ‘sweep’ is, the safer the system. All Alphasonics systems operate at +/- 12Khz minimum, as we sweep to the adjacent harmonic frequencies, making our patented ‘Enhanced SuperSweep’ technology by far the safest on the market. Although we call this technology ‘Dual Frequency’, we are actually employing 6 frequencies. In all we have seven harmonic frequencies to choose from on the particular transducers that we use for anilox cleaning, so choosing 2 mean harmonic frequencies, then sweeping to the harmonic frequency either side, we use 6 out of the seven we have at our disposal. To support this, in our 30 years of business, Alphasonics have never had a complaint regarding roll damage. Not one.
In essence, the lower the frequency, the more aggressive will be the action of the ultrasonics. So, anyone who tells you that you can regularly clean your coating aniloxes in the same single, low frequency ultrasonic tank as your process aniloxes is sadly talking nonsense. Maybe if you’re only going to clean your rolls once every few weeks, it is possible you might ‘get away with it’. However, isn’t the whole idea of using higher line aniloxes to improve print quality? These aniloxes by their nature require cleaning more regularly, daily if possible, to maintain consistency. Most certainly, it is required between ink changes, so contamination layering does not occur.
What Alphasound DF offers the user is a Super Sweeping “Soft Brush” at 55Khz and a “Feather Duster” at 98Khz. The aim is that the soft brush, 55Khz setting is used to get the rolls clean and the feather duster, 98Khz setting is used for the daily/hourly cleaning regime. If, for whatever reason, the roll is not cleaning using high frequency, the low frequency setting would be re-employed. However, it must be noted that Alphasound low frequency at 55Khz is still significantly higher and as such more gentle than anything else on the market.
What Betasound DF offers the user is a Super Sweeping, combined frequency “Soft Brush” at 55 and 67Khz and a “Feather Duster” at 98 and 132Khz together. Again, as with Alphasound, the lower frequency pairing would be used to get the rolls clean and the higher frequency pairing would be used for more regular cleaning to keep the rolls clean. Betasound should be employed where very high screens are being utilised as in High Definition Flexography, or when very regular cleaning is required. The reason that Betasound technology is so safe for ultra- high screen aniloxes and very regular cleaning is because employing two frequencies simultaneously alongside a Super Sweep ensures that the ultrasound is extremely evenly distributed throughout the tank fluid (within 1.5mV). This totally eliminates the notorious “Hot Spots” and “Cold Spots”, the primary cause of damage to rolls through ultrasonic cleaning.
So, getting back to the initial question, ‘Do you need Dual Frequency?’ In short, if you are running coating aniloxes or will clean your rolls infrequently then, no. A single frequency system should be adequate, providing it has the required safety features. If you are running medium to high line aniloxes and/or wish to clean your rolls regularly then yes, most certainly. If you are running ultra-high line aniloxes and wish to clean them very often, we would recommend our patented Betasound technology, developed especially for this purpose.