| |
Ultrasonic cleaners use high frequency sound waves to improve the cleaning action of a solution. The cleaning action can be gentle to clean delicate electronic components or tough enough to remove chips and grease from machined parts. The action depends on the frequencyand the level of power. The frequencies range from 20 khz to over 170 khz, ( 1 khz [kilohertz] = 1000 cycles). The most common frequencies are 25 khz, 40 khz and 80 khz. The low frequency provides rough cleaning action and should only be used for tough, heavy parts. Frequencies below 25 khz may cause audible problems. The higher the frequency, the gentler the cleaning action. When an object is exposed to a single frequency, it can start to vibrate at that frequency or a multiple (harmonic) therof. Manufacturers will vary the frequency around the stated frequency +/- 1 or 2 khz. This is called sweeping and keeps the part being cleaned from vibrating.
Normaly, the shape of the sound wave is a sine wave. Some manufacturers have developed, and patented other wave shapes to improve the cleaning efficiency. These systems usualy are more expensive. The user has to judge if the added cost is warranted.
When the sound waves travel through the solution, millions of tiny gas bubbles are formed which, when they come in contact with the part to be cleaned, implode just like a bursting baloon. The implosion is called cavitation. The energy released by the cavitation, tears away theparticles from the part to be cleaned. The warmer the solution, the more bubbles are created. Therefore, most manufacturers offer heaters in their system
When multiple parts are cleaned, exposure of all surfaces to the sound waves is important. The same is true when the inside of holes must be cleaned. Rotating part holders, tumbling baskets and oscillating systems are available from most manufacturers. An important factor to consider is the power of the sound generator. The greater the power, the greater the cleaning action. Manufacturers state the power levels in (kw) Peak Power, Average Power, RMS or Input Power. Some manufacturers say which rating they use, some do not. We will endaever to use RMS (Root Mean Square) for all units for comparison purposes.[ eg: 120 volts is an RMS value, its peak value is 169.7 volts ) Ultrasonic Cleaners are divided into Industrial tank and Bench Top
|
