Cavitation Parts Washing Explained – RAMCO's Multiple Rollover

RAMCO Parts Washers > Cavitation Parts Washing Explained – RAMCO’s Multiple Rollover

Cavitation Parts Washing Explained – RAMCO’s Multiple Rollover

Parts Washing and Cavitation: The Ultrasonic Answer

Cavitation, also known as Ultrasonic Cleaning generates sound waves through liquid at selected frequencies to that break down contaminants such as dirt and grime. These waves cause microscopic oscillations that strike the surface of the object and dislodge particles from its surface. Cavitation parts washing has proven to be among the most efficient cleaning methods, particularly when the parts are of intricate design or are unable to tolerate some of the stronger chemicals used for more durable parts.


The dynamic components of cavitation are millions of microscopic bubbles that are created when the sonic frequencies are generated. Depending upon the attributes of the parts to be cleaned, the frequencies will either be high or lower frequencies. For instance, higher frequencies generate streams of small, moderately active bubbles that are effective for cleaning sensitive parts. Conversely, lower frequencies work much better for heavier, larger and more durable industrial parts, and the bubbles produced by them will be larger and move with greater force.

The action of the bubbles themselves is a complex series of transformations that begins with the bubbles looking as one would expect: round bubbles. As they come into contact with any surfaces, they implode, morphing roughly into a c-shaped bubble. As the force of liquid from jets passes through each bubbles’ center, hitting the part’s surface, they enhance the chemical action as well, stripping off contaminants which are then washed away from the parts.

RAMCO’s Preventative Approach

While this is all relatively straightforward, at RAMCO we are always on the alert for issues that can and do occasionally occur, unless fully understood from both causal and preventative perspectives.

Entrapment

One such issue is air entrapment. This can happen when parts are multi-planar, have fine undercutting, or have blind holes. Such characteristics can cause air to become “trapped” in areas and become an obstacle, preventing those areas from being cleaned.

To overcome the difficulties associated with air entrapment, a number of things need to be taken into account, especially since it’s virtually impossible to change the shape of a given part:

  The placement/positioning of the parts to be washed. With careful positioning, it’s possible to

    cause the parts to drain effectively.

  Submerging the parts. At this point a careful inspection of the parts and their positions can be

    made, then trapped air can be manually released.

  Agitation or rotation of parts. Such a procedure is not always feasible since it can cause

    damage to certain parts. However, when it can be done without risk the parts’ integrity,

    this process can irrigate problem areas and release trapped air.

Cavitation Erosion

Additional care must be taken if any given parts might be subject to damage from the ultrasonic forces at work. Some materials are sensitive to vibrations or to being subjected to force, resulting in erosion of the part’s surface. Higher frequencies, being less forceful, are less likely to cause damage than the lower frequencies.

The parts to be cleaned are not the only components at risk for surface erosion. The washing machinery itself is subject to this condition as well. Possibly the most crucial area is the cavitation erosion of the machine’s ultrasonic transducers – a topic that’s taboo more often than not among manufacturers of cavitation apparatus. At RAMCO we face this occupational hazard head-on, understanding that this type of erosion will eventually occur over time.

Cavitation erosion on the surface of a transducer.

During the cavitation parts washing process, the powerful ultrasonic forces unleashed on the transducer can actually remove metal from the transducer’s surface, causing pitting and compromising the transducer’s integrity. The factors at play here are a) the operating time – the more time and the longer the machinery is used, the greater the chances of erosion;, b) the degree of corrosive properties of the chemical agents being used; and c) the specific temperature being employed to do the cleaning – in general, the higher the temperature, the greater the risk.

Taking such factors into account can help extend transducer life. In addition, hard chrome plating of the transducer’s surface as well as utilizing heavy gauge metal for the transducer face have both been shown to be effective. However, it is virtually impossible to completely stop cavitation erosion from occurring.

In this regard, RAMCO’s recommendations as to what type of transducer is to be used will go a long way toward extending transducer life.

Matching the Machine to the Task

Mitigating these potential issues is of major priority when pairing parts with the right ultrasonic machines and cleaning solutions. The size and shape of ultrasonic tanks can have significant impact upon fluid circulation and agitation. Furthermore, parts that are submerged into the tank can actually absorb, to varying degrees, the ultrasonic energy that is being generated. For example any parts located between the ultrasonic transducers can adversely impact performance.

Enhanced Cleaning with the Multiple Rollover Process

Occasions may arise when it’s necessary to augment the cavitation process in order to ensure the best results. To that end, RAMCO pioneered the technique of Multiple Rollover. Attempts to copy this revolutionary process are numerous, but it has never been successfully duplicated. There are situations when the cavitation process, in order to be most effective, can be combined with additional cleaning processes. Superior washing outcomes are possible (depending upon the parts to be cleaned and their specific attributes), by alternating between Cavitation and carefully calibrated additional cleaning methods such as Solution Turbulation or Platform Oscillation. Multiple Rollover, in addition to it cleaning benefits, can markedly reduce washing times.

During solution turbulation, as the cleaning agents move into and around the parts, contaminants can be flushed from channels, blinds holes and other detailed regions. Parts which may be vulnerable to excessive ultrasonic exposure, such as aluminum components common to the aerospace industry, can be thoroughly cleaned without risking damage.

Platform Oscillation, as it moves the parts through the solution, can be used intermittently as well, particularly in situations where stationary cleaning outcomes might otherwise fall short. Not only is cleaning enhanced by the agitation, but cleansing action is further improved as the cleaning agent flows across the parts’ surfaces with every oscillation. In addition, contaminants caught in any of the entrapment regions are systematically flushed away and drained.

For a free consult with one of our experts, contact the RAMCO factory at 800-553-3650.

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