Property of Ultrasonic Power Corporation -
© 2017
Publication #170119-jsw
18
ULTRASONIC
OUTPUT
FREQUENCY:
Many technical articles claim that high frequencies penetrate more and lower frequencies are
more aggressive. The majority of the ultrasonic cleaning that is done in industrial applications
today uses 40 kHz as the base frequency. Lower frequencies, such as 20 - 25 kHz, are used for
large masses of metal, where ultrasonic erosion is of little consequence. The large mass dampens
or absorbs a great amount of the ultrasonic cleaning power.
WATTS
PER
GALLON:
In general, smaller parts, requiring more critical cleaning, require higher watts per gallon to
achieve the desired level of cleanliness. Most industrial ultrasonic cleaning systems use watt
density from 50 - 100 watts per gallon. However, there is what is known as "the large tank
phenomenon", which indicates that tanks over 50 gallons usually require only about 20 watts per
gallon. The only explanation available is a point of diminishing returns with regard to ultrasonic
power.
LOADING:
Loading of the part(s) to be cleaned must be considered, with regard to the shape and density. A
large dense mass will not allow internal surfaces to be thoroughly cleaned (i.e., metal castings).
A rule of thumb for loading is that the load by weight should be less than the weight of half the
water volume, i.e., in 5 gallons, approximately 40 lbs. of water, the maximum work load should
be less than 20 pounds. In some cases, it is better to ultrasonically clean two smaller loads, rather
than one larger load.
The above information is not meant to give all the details to utilize ultrasonic cleaning
techniques. This information is to help the process designer gain some insight into the variables
of industrial ultrasonic cleaning.
