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Capstone's Office Staff
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WA Contractor's No.: CAPSTCC106J5 North Idaho Contractor's No.: RCE-13883 Ultrasonic Cleaning Ultrasonic cleaning is a
result of sound waves introduced into a cleaning liquid by means of a series of
"transducers" mounted to the cleaning tank. The sound travels
throughout the tank and creates waves of compression and expansion in the
liquid. In the compression wave, the molecules of the cleaning liquid are
compressed together tightly. Conversely, in the expansion wave, the molecules
are pulled apart rapidly. The expansion is so dramatic that the molecules are
ripped apart, creating microscopic bubbles. The bubbles are not seen by the
naked eye since they are so small and exist for only a split second of time. The
bubbles contain a partial vacuum while they exist. As the pressure around the
bubbles becomes greater, the fluid around the bubble rushes in, collapsing the
bubble very rapidly. When this occurs, a jet of liquid is created that may
travel at this very high rate. They rise in temperature to as high as 5000
degrees C, which is roughly the temperature of the surface of the sun. This
extreme temperature, combined with the liquid jet's velocity provides a very
intense cleaning action in a minute area. Because of the very short duration of
the bubble expansion and collapse cycle, the liquid surrounding the bubble
quickly absorbs the heat and the area cools quickly. As a result, the tank and
liquid becomes only warm and does not heat up due to the introduction of parts
during the cleaning process. To introduce ultrasonic energy into a
cleaning system requires an ultrasonic transducer and an ultrasonic power supply
or "generator." The generator supplies electrical energy at the
desired ultrasonic frequency. The ultrasonic transducer converts the electrical
energy from the ultrasonic generator into mechanical vibrations. Ultrasonic Generator The ultrasonic generator converts electrical energy from
the line which is typically alternating current at 50 or 60Hz to electrical
energy at the ultrasonic frequency. This is accomplished in a number of ways by
various equipment manufacturers. Current ultrasonic generators nearly all use
solid state technology.
There have been several relatively recent innovations in
ultrasonic generator technology which may enhance the effectiveness of
ultrasonic cleaning equipment. These include square wave outputs, slowly or
rapidly pulsing the ultrasonic energy on and off and modulating or
"sweeping" the frequency of the generator output around the central
operating frequency. The most advanced ultrasonic generators have provisions for
adjusting a variety of output parameters to customize the ultrasonic energy
output for the task. Square Wave Output Applying a square wave signal to an ultrasonic transducer
results in an acoustic output rich in harmonics. The result is a multi-frequency
cleaning system which vibrates simultaneously at several frequencies which are
harmonics of the fundamental frequency. Multi-frequency operation offers the
benefits of all frequencies combined in a single ultrasonic cleaning tank. Pulse In pulse operation, the ultrasonic energy is turned on and
off at a rate which may vary from once every several seconds to several hundred
times per second.
The percentage of time that the ultrasonic energy is on
may also be changed to produce varied results. At slower pulse rates, more rapid
degassing of liquids occurs as coalescing bubbles of air are given an
opportunity to rise to the surface of the liquid during the time the ultrasonic
energy is off. At more rapid pulse rates the cleaning process may be enhanced as
repeated high energy "bursts" of ultrasonic energy occur each time the
energy source is turned on.
Smoked Damaged Blinds Before
After
The
Theory of Sound Waves
In order to understand the
mechanics of ultrasonics, it is necessary to first have a basic understanding of
sound waves, how they are generated and how they travel through a conducting
medium. The dictionary defines sound as the transmission of vibration through an
elastic medium which may be a solid, liquid, or a gas. Sound Wave Generation - A
sound wave is produced when a solitary or repeating displacement is generated in
a sound conducting medium, such as by a "shock" event or
"vibratory" movement. The displacement of air by the cone of a radio
speaker is a good example of "vibratory" sound waves generated by
mechanical movement. As the speaker cone moves back and forth, the air in front
of the cone is alternately compressed and rarefied to produce sound waves, which
travel through the air until they are finally dissipated. We are probably most
familiar with sound waves generated by alternating mechanical motion. There are
also sound waves which are created by a single "shock" event. An
example is thunder which is generated as air instantaneously changes volume as a
result of an electrical discharge (lightning). Another example of a shock event
might be the sound created as a wooden board falls with its face against a
cement floor. Shock events are sources of a single compression wave which
radiates from the source.
Benefits
of Ultrasonics in the Cleaning
Ultrasonics
Speeds Cleaning by Dissolution
Some contaminants are comprised of insoluble
particles loosely attached and held in place by ionic or cohesive forces. These
particles need only be displaced sufficiently to break the attractive forces to
be removed.
Cavitation and implosion as a result of
ultrasonic activity displace and remove loosely held contaminants such as dust
from surfaces. For this to be effective, it is necessary that the coupling
medium be capable of wetting the particles to be removed. Complex
Contaminants
Contaminations can also, of course, be more complex in nature, consisting of
combination soils made up of both soluble and insoluble components. The effect
of ultrasonics is substantially the same in these cases, as the mechanical
micro-agitation helps speed both the dissolution of soluble contaminants and the
displacement of insoluble particles. Ultrasonic activity has also been
demonstrated to speed or enhance the effect of many chemical reactions. This is
probably caused mostly by the high energy levels created as high pressures and
temperatures are created at the implosion sites. It is likely that the superior
results achieved in many ultrasonic cleaning operations may be at least
partially attributed to the sonochemistry effect. A
In the above illustrations, the surface of the part being cleaned has been
represented as a flat. In reality, surfaces are seldom flat, instead being
comprised of hills, valleys and
Maximizing
Overall Cleaning Effect
Temperature is important to achieving maximum
cavitation. The effectiveness of the cleaning chemical is also related to
temperature. Although the cavitation effect is maximized in pure water at a
temperature of approximately 160ェ, optimum cleaning is often seen at higher or
lower temperatures because of the effect that temperature has on the cleaning
chemical. As a general rule, each chemical will perform best at its recommended
process temperature regardless of the temperature effect on the ultrasonics. For
example, although the maximum ultrasonic effect is achieved at 160ェ, most
highly caustic cleaners are used at a temperatures of 180ェ to 190ェ because
the chemical effect is greatly enhanced by the added temperature. Other cleaners
may be found to break down and lose their effectiveness if used at temperatures
in excess of as low as 140ェ. The best practice is to use a chemical at its
maximum recommended temperature not exceeding 190ェ Degassing of cleaning solutions is extremely
important in achieving satisfactory cleaning results. Fresh solutions or
solutions which have cooled must be degassed before proceeding with cleaning.
Degassing is done after the chemical is added and is accomplished by operating
the ultrasonic energy and raising the solution temperature. The time required
for degassing varies considerably, based on tank capacity and solution
temperature, and may range from several minutes for a small tank to an hour or
more for a large tank. An unheated tank may require several hours to degas.
Degassing is complete when small bubbles of gas cannot be seen rising to the
surface of the liquid and a pattern of ripples can be seen.
The Ultrasonic Power delivered to the cleaning
tank must be adequate to cavitate the entire volume of liquid with the workload
in place. Conclusion Properly utilized, ultrasonic energy can
contribute significantly to the speed and effectiveness of many immersion
cleaning and rinsing processes. It is especially beneficial in increasing the
effectiveness of today's preferred aqueous cleaning chemistries and, in fact, is
necessary in many applications to achieve the desired level of cleanliness. With
ultrasonics, aqueous chemistries can often give results surpassing those
previously achieved using solvents. Ultrasonics is not a technology of the
future -- it is very much a technology of today.
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Contact us today to discuss your options and how Capstone can help you as quickly as possible. We understand the heartbreak that accompanies a disaster. When a disaster strikes your home or business it can be a devastating experience. Your valuables, memorabilia, and all the things that mean so much to you may be harmed. Capstone employees will always have the utmost respect for you and your property. Our commitment is to get your life back to normal as quickly as possible. We will work with your insurance company to restore your property to its pre-disaster condition. From the initial call for emergency service, to each and every aspect of putting things back together again, Capstone is your full-service restoration company. You can be assured that communication will be maintained throughout the restoration process. Customer Satisfaction is our number one priority!
(509) 468-4981 * FAX (509)
468-5081 Copyright ｩ 2001-2009. All Rights Reserved. Capstone Construction Co., Inc. Mark E. Anderson, Webmaster - Email: manderson@capstone247.com
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convolutions
of all description. The illustration at the right shows why ultrasonic energy
has been proven to be more effective at enhancing cleaning than other
alternatives, including spray washing, brushing, turbulation, air agitation, and
even electro-cleaning in many applications. The ability of ultrasonic activity
to penetrate and assist the cleaning of interior surfaces of complex parts is
also especially noteworthy.
