A Closer Look at Ultrasonics

Does ultrasonic cleaning really work? If you ask a dozen people who at one time or another used it for contents cleaning, I'm sure that the response would range from "yes, absolutely" to "no" to somewhere in the middle.

To get the real answer, a closer look into this technology is warranted.

Ultrasonic cleaning has been around for more than 40 years, and is routinely used for a variety of specialty cleaning applications. It is capable of delicate operations, such as removing sub-micron-sized particles from sensitive components, yet aggressive enough to dislodge baked-on carbons from engine parts. In addition, ultrasonic cleaning allows the operator to process numerous items simultaneously in a fraction of the time it takes to clean one by hand.

Hospitals, dentist offices, jewelry stores, aviation repair facilities, automotive and radiator repair shops, manufacturing facilities and even electronic repair businesses are examples of some facilities that commonly use ultrasonic cleaning.

Restoration Applications
Restoration cleaning of contents is challenging simply due to the diverse range of contaminates encountered. Soot, oils, greases, heat scale, rust, oxides, hot and cold smoke contamination, as well as a variety of natural, protein and synthetic residues, may be present within the confines of a single packout. Because of this diversity, various cleaning procedures must be employed. The use of just one ultrasonic-cleaning procedure won't apply to all cleaning requirements.

Education is the Key
Ultrasonic cleaning is a science. In order to achieve successful results one must be trained in this field. Today there are companies who offer complete and comprehensive hands-on training programs specifically for contents restoration. These programs are invaluable to those currently offering ultrasonic cleaning.

Understanding the Make-Up of a Packout
A wide variety of materials and residue are sure to be encountered in a packout. It is important to have a basic understanding of the material types and physical characteristics of the items being processed and restored. Ultrasonic restoration is best accomplished by addressing the packout by category. Separating and packing contents by category or type makes it easier to designate a specific process for each type of contents, such as with electronic and electrical items; delicates; collectibles; metals (corrosion and oxide removal); mold contaminated items; and general contents. Contents should be boxed and routed for the specific type of processing needed.

Each of these categories requires a specific ultrasonic process, according to the type and level of contaminates on the items. Consistent cleaning results are achieved by applying the correct procedures and techniques based on the category of contents.

How Does it Work?
The principle behind ultrasonics is a phenomenon known as cavitation. The cleaning or scrubbing activity is achieved by microscopic cavitation bubbles, which are produced and instantaneously implode, releasing extreme heat and scrubbing energy. Individually these implosions are microscopic events, but because there are millions of bubbles imploding simultaneously, a unique and powerful cleaning environment is created.

Choosing the Correct Procedure
Successful ultrasonics processing depends on the combination and control of four vital factors: power, frequencies, temperature and cleaning agents. An effective ultrasonic cleaning unit must have sufficient power and be able to efficiently convert that power into abundant cavitation energy. The larger the cleaning vessel, the more component power is required.

The most common frequencies used in ultrasonic cleaning range from 25 to 80 kHz (One kHz equals 1,000 cycles per second). Higher frequencies produce more abundant cavitation; however, the bubble size is smaller and less powerful. Conversely, lower frequencies produce less abundant cavitation, but the cavity implosions are more forceful. Although there are times that 25 kHz and 80 kHz may be suitable, the vast majority of cleaning applications are best served by a 40 kHz frequency.

Fluid temperature is also an important factor in the cleaning process. Ultrasonic cleaning is most effective when fluid temperatures are high. The optimum temperatures for most restoration applications range from 120 to 140 degrees. For certain heavy-duty cleaning applications, higher temperatures may be required. When cleaning delicate items, lower temperatures should be employed.

Not all cleaning agents are compatible with ultrasonic cleaning, and using an incompatible chemical will render an ultrasonic cleaner ineffective. Many chemical characteristics must be considered in the design of an ultrasonic cleaning agent. A proper formulation will facilitate an abundance of cavitation activity, creating an ideal cleaning environment specific to the residue and material being restored.

An ultrasonic cleaning agent must have adequate wetting qualities, as this has a direct bearing on the intensity of the cavitation activity. The agent must also have sufficient surfactant qualities in order to suspend the contaminants; otherwise, they will settle back onto items being cleaned.

Effective cleaning agents should be formulated specifically for the application and must be able to break the bonds that hold the contaminants to the item. Additionally, all cleaning agents must be formulated to be user safe and environmentally compatible.

As with any restoration-related service, training and education are the keys to success. This is especially true of ultrasonic cleaning. With comprehensive training courses now readily available, ultrasonic cleaning is a technology that may well become the status quo for the restoration industry.