Here is an article that I searched for on the web. It is loong, but if you read it, you will have a greater understanding of ultrasonic cleaning processes. It's an eye opener for sure!
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Ultrasonic Cleaning Systems
Agitation systems that utilize ultrasonic waves to remove soils from surfaces are commonly employed in almost all areas of critical and industrial cleaning. This cleaning process works by way of a transducer, which converts electricity to intense, high-frequency ultrasound vibrations within a cleaning bath.
Cleaning Via Cavitation
Cavitation occurs when ultrasonic waves cause pressure gradients within the cleaning fluid, forming bubbles within low-pressure areas. These bubbles expand until they enter a region of pressure high enough to cause their collapse. Small voids (cavitations) open and collapse at the surface of the part being cleaned.
The energy created by these cavitations can effectively loosen and discharge many contaminants from the surface. This action is efficient to clean even complex heterogenous surfaces that contain numerous crevices, holes, and pores.
The cavitations created by ultrasonics have been found in many cases to enhance removal of hydrophobic solvent cleaning films by 30 to 40 percent, compared with spray rinsing methods. Ultrasonic agitation is thus very effective in increasing the degree of cleaning that may otherwise be obtained.
Compatibility Concerns
Ultrasonics is most effective with hard substrates, such as metals, glass, and ceramics, and is not as effective in cleaning soft materials. In most cases, cleaning efficiency decreases with decreasing particle size.
This cleaning process can be used with aqueous, semi-aqueous, and solvent-based systems, and the technique is compatible with numerous solvents, including fluorocarbons, caustics, acids, acetone, alcohols, ether, and other hydrocarbons. Ultrasonics can potentially be used in a vapor degreaser, but only in the liquid boil sump since ultrasonic energy does not transmit through vapor.
Temperature, vapor pressure, surface tension, viscosity, and density of the cleaning fluid all influence the performance of an ultrasonic system. The magnitude of the latter four properties varies with temperature. The viscosity and density will affect the degree of shear imparted by the ultrasonic energy. Vapor pressure will affect the extent of cavitation, and the wettability of the surface will be affected by the surface tension of the cleaning fluid.
The temperature and additive concentrations typically used in ultrasonics are a compromise between the higher temperatures and concentrations needed for optimal cleaning and the lower temperatures and concentrations necessary for optimal energy transfer.
Equipment, Frequency, Chemistry
Due to the vibrational energy, parts cannot rest on the tank bottom. The baskets used to hold the parts should not absorb any ultrasonic energy, which would effectively reduce the shear imparted on a part's surface, thereby reducing the cleaning efficiency. As a rule of thumb, the sum of a part's cross-sectional areas should not be greater than 70 percent of the tank's cross-sectional area.
Vertical tanks, with a large height:width ratio, that have transducers on the tank bottom provide a more cost-effective method of parts cleaning. The workload mass-to-volume ratio (25 to 30 percent for general parts cleaning) should be no greater than 10 to15 percent for precision applications.
The frequency of the ultrasonic energy is the most crucial element within an ultrasonic system. More noise is created at lower frequencies. At less than 20 kHz, the ambient noise might be at a level not in conformance with OSHA safety standards. On-site monitoring should therefore be performed.
Lower frequency ultrasonics, which provide more aggressive cleaning action, produce larger cavitation bubbles, and this type of process is not generally used for precision cleaning. Cleaning applications typically fall in the frequency range of 40-400 kHz. Frequencies between 72 and 104 kHz are most often employed, in conjunction with a subsequent distilled water rinse, to minimize cavitation erosion that would occur at other frequencies.
Surfactants, wetting agents, and other additives are often difficult to remove from the substrate. This may entail additional quantities of water, higher temperatures, and longer rinse times, as feasible. For many precision applications (eg, microcircuitry and precision optics), longer cycle times may introduce contaminants to the substrate, especially those with complex geometries. Leaching of construction materials may be a problem.
When using flammable solvents within an ultrasonics environment, "intrinsically safe" tanks and equipment must be employed. Standing wave damage is also a possibility within the cleaning bath, incurring frequency resonance damage to the parts being cleaned. This can be corrected by the use of a sweeping frequency generator.
Regulatory compliance with pertinent OSHA, EPA, FCC, and other federal, state, and local requirements is a necessary consideration when using ultrasonics. Also, interference with computers, microprocessors, etc. must be controlled. Line-conducted interference is controlled by use of a suitable radio frequency (RF) filtering device at the AC power supply. Radiated RF interference can be avoided by grounding and scaling the metalwork, which houses the generator and transducers, and the braided metal sleeve, which acts as one of the conductors of the interconnecting coaxial wiring.
References
Fuchs FJ. Ultrasonic Cleaning: Fundamental Theory and Application. Presented at the 1997 Precision Cleaning Conference, Rosemont, Ill.
Manchester RC. The precision cleaning of delicate structures using aggressive ultrasonics without damage. Precision Cleaning. April 1997;5.
Awad SB. Ultrasonic cavitations and precision cleaning. Precision Cleaning. November 1996;4.
Bardina J. Methods for surface particle removal: a comparative study. In: Mittal KL, ed. Particles on Surfaces. New York: Plenum Press; 1988;1.
This article was found at
http://www.cleantechcentral.com/KnowledgeBase/TechnologySpotlight/ultrasonic.asp .
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Now when I can locate the fluid, I'll be in business. Maybe my local photo shop, or radiator shop could help me. If anyone has any suggestions on locating UltraSonic cleaning fluid, please email me at
webmaster@americanwebsiteservices.com
Thanks!
Looks like team work will pay off, but if you have any old 6 cylinder fuel distributors hangin around that are bad, let me know. Hope this helps someone in the future!