Technical Information

Conditions that Affect Ultrasonic Baths – Filling the cleaning tank with water, or other solution, is only the beginning of attention that must be paid to keeping cleaning optimal. Some factors to consider are:

  • Temperature – Aqueous system operating temperature should generally be between 130 to 160 degrees F. Lower temperatures diminish ultrasonic cavitation and chemical effectiveness. Higher temperatures generally enhance chemical action but soften the cavitation implosion as temperatures approach the boiling point of the solution.
  • Chemical concentration – too low concentration causes the bath to saturated quickly and lose the ability to hold dirt. Too high concentration can cause the same conditions as excessive impurities in the bath and impede cleaning. Consult your chemical supplier for recommendations.
  • Entrapped air – results in softened cleaning action with ultrasonics. See Degassing
  • Agitation – excessive agitation disturbs the sound wave and can introduce excessive air to be entrapped into the bath. Both disrupt the cavitation cleaning action.
  • Impurities – excessive impurities will produce at similar effect as a gassy solutions since the impurities will occupy the void in the bubbles resulting in diminished cavitation.
  • Pressure – cleaning systems generally operate at open atmospheric pressure. Sometimes higher pressure situations arise and the additional compression on the cleaning bath can diminish effective cavitation except on the highest power systems.
  • Parts and Parts Baskets – nested parts in baskets can disturb and diminish cavitation within the nest that even long exposure time will not overcome. Therefore parts orientation, configuration and nesting are all factors to be considered in process development. Basket/carrier construction such as fine wire mesh, plastic and heavy frames are cavitation damping. top

Filtration – Filtration is used to remove particulate matter from the cleaning bath solution thus extending the effective life of the bath. Filtration is an application field into and or itself. The filtration requirements should be analyzed and developed at the time the cleaning process is developed. There are many alternatives for filtration systems from simple cartridge filters to complex multi stage system, off line systems, transfer systems, multi chamber and more. Cost payback analysis is strongly recommended because often filtration is considered an ancillary item to be purchased at the lowest initial cost but, in fact, a properly designed filtration system can substantially reduce operating costs. top

Part Orientation – Part orientation in any cleaning is important and not more so than in ultrasonic cleaning. Since primary ultrasonic cavitation is directional and only secondary cavitation begins to come at different angles, parts that mask critical surfaces must have orientation taken into account. Large and convoluted parts can shadow other surfaces on the same part. Small parts in a batch can mask through nesting. Blind and small through holes can trap air and thus keep cleaning solution and ultrasonics cavitation from taking place in the cavity. These can be overcome by rotation, oscillation, fixturing, gentle fluid circulation and other means. One of the newest concepts is W3 Surround which has the objective of surrounding the part load with ultrasonic power and as long as solution can flood and empty from the part, successful scrubbing can take place. Surround. top

Process Development – This is the method of analysis and decision making involved with establishing the cleaning process and correct equipment. W3 views this as a four step method starting with an analysis of the problem for the needs of the customer and primarily involves only the user to compile. Step two is to develop the cleaning process through actual testing and evaluation as a team between the user and W3. Processes include pre-wash, wash, rinse, inhibit, dry, filter, control among other parameters. Once the process is settled, step three, done by user and W3 together, consists of determining the other machine and site parameters that the equipment and cleaning must operate in. these include material handling, available space, service utilities, installation limitations, among other items. Finally, the last step is selection of the correct equipment proposed by W3 and evaluated with the user. You can start the procedure by going to Your Process. top

Processes Other Than Parts Cleaning – Ultrasonics and sonics, in general, can be used successfully to disperse nano size materials in various liquids, create emulsions, reduce particle size as well as separation operations. W3 has experience in these fields and considers projects on a stand alone basis. If you have a situation to discuss, contact W3 directly. top

Types of Transducers – Two main types of transducers exist today – piezoelectric and magnetostrictive. Piezoelectric transducers are crystal based, generally of lead zirconate titanate, which changes dimension when a current is applied. Magnetostrictive transducers are generally nickel materials with a coil of wire around them. With power applied, the nickel changes dimension in the electromagnetic field.
Nickel can be driven much harder than crystal materials. The crystal material is generally sandwiched between metal ends with a bolt compressing the entire assembly. Each individual assembly is bonded in an array, with either epoxy or braze, to a radiating surface. W3 piezo transducers are lead-zirconium-titanate crystals. Most magnetostrictive nickel transducers are zero spaced lamination stacks with a coil of wire around a leg and brazed in an array to the radiating surface. All that is, except W3. W3 nickel laminations are spaced apart and cover the entire radiating surface and excited all at the same time as a unit through a common coil creating a piston effect for the sound wave in the bath. The resulting sound wave produces extremely high cavitation power. top

Ultrasonic Cleaning – Mechanical sound waves at ultrasound frequencies are produced from a power supply through a transducer into a liquid solution. Every cycle generates sound waves which produce lower and higher pressure areas at void/bubble areas in the bath. During the lower pressure half of the cycle, the bubble is expanded and during the higher pressure half of the cycle, the bubble is violently collapsed, or imploded. This action is cavitation and the violent implosion pulls matter around the bubble into the area originally occupied by the void. The action, according to this writer's analogy, is likened to a black hole in space on a microscopic level. Even at this level, the energy of each implosion is in the neighborhood of 10,000 degrees and 20,000 psi. Performed often enough like 20,000 or more times every second, remarkable results can be obtained. The larger the bubble, the more power from the transducer is required to collapse the bubble but the larger the bubble, the greater the energy of the implosion. W3 ultrasonic equipment, with its proprietary designs, produces the most powerful ultrasonic action available. top

Ultrasonic Frequencies - Sonics is the field of acoustics that deals with mechanical waves at all frequencies in all substances while ultrasonics is viewed as the wavelengths that are above the normal range of human hearing, typically around 18 kHz and ultrasonic cleaning is generally defined as the field of sonics that deals with mechanical waves in liquid solutions. While frequencies have steadily increased over the years to megasonic range, most all effective parts cleaning is accomplished with frequencies between 20 kHz and 80 kHz. Ultrasonic cleaning power tracks frequency in reverse with maximum cleaning power at the low frequency and declining as the frequency increases. W3 does not supply a frequency above 34 kHz for that reason. The vast majority of W3 applications involve 20 kHz products which we have effectively and successfully applied in all types of industrial cleaning applications for over 35 years. top

W3 product philosophy is based in making the product fit the application rather than making the application fit the product.

All selections of equipment are first preceded with a thorough analysis of your specific application and production needs with one of our experienced W3 Ultrasonic application personnel.

Start the Process Development analysis yourself or Contact W3 directly.