Ultrasonic Cleaning 101

What is Ultrasonic Cleaning?

Ultrasonic Cleaning involves the use of high-frequency sound waves, above the range of human hearing, to remove a variety of contaminants from parts immersed in aqueous cleaning media. The contaminants can be dirt, oil, grease, buffing/polishing compounds, and mold release agents, just to name a few. Materials that can be cleaned by ultrasonic cleaning systems include metals, glass, ceramics, and so on. Ultrasonic agitation can be used with a variety of cleaning agents.

Typical applications found in the metals industry are removing chips and cutting oils from cutting and machining operations, removing buffing and polishing compounds prior to plating operations, and cleaning greases and sludge from rebuilt components for automotive and aircraft applications.

Bluewave Ultrasonics logo

Benefits of Ultrasonic Cleaning

Ultrasonic cleaning is powerful enough to remove tough contaminants, yet gentle enough not to damage the substrate.  It provides excellent penetration and cleaning in the smallest crevices and between tightly spaced parts in a cleaning tank. The use of ultrasonic cleaning machines has become increasingly popular due to the restrictions on the use of chlorofluorocarbons. The use of ultrasonics enables the cleaning of intricately shaped parts with an effectiveness that corresponds to that achieved by vapor degreasing, but in a more comprehensive, high-tech, and ecologically friendly manner.

The Process of Blue Wave Ultrasonics Precision Cleaning

How does ultrasonic cleaning work? In a process termed cavitation, micron-size bubbles form in the ultrasonic cleaning fluid and grow due to alternating positive and negative pressure waves in a solution.  The temperature inside a cavitating bubble can be extremely high, with pressures up to 500 atm.  Ultrasonic cleaning systems create an implosion event, which, when it occurs near a hard surface, changes the bubble into a jet about one-tenth the bubble size, which travels at speeds up to 400 km/hr toward the hard surface.  With the combination of pressure, temperature, and velocity, the jet frees contaminants from their bonds with the substrate.  Because of the inherently small size of the jet and the relatively large energy, ultrasonic cleaning can reach into small crevices and remove entrapped soils very effectively.

Blue Wave Generating Results from Ultrasound

In order to produce the positive and negative pressure waves in the ultrasonic cleaning fluid, a mechanical vibrating device is required.  Ultrasonic cleaning systems manufacturers make use of a diaphragm attached to high-frequency transducers.  The transducers, which vibrate at their resonant frequency due to a high-frequency electronic generator source, induce amplified vibration of the diaphragm.  This amplified vibration is the source of positive and negative pressure waves that propagate through the solution in the tank.  The operation is like the operation of a loudspeaker except that it occurs at higher frequencies.  When transmitted through water, these pressure waves create the cavitation processes for ultrasonic cleaning solutions.

Test Photo

Blue Wave Offers The Right Equipment For The Job

The basic components of an ultrasonic cleaning system include a bank of ultrasonic transducers mounted to a radiating diaphragm, an electrical generator, and a tank filled with aqueous solution. A key component is the transducer that generates the high-frequency mechanical energy. There are two types of ultrasonic transducers used in the industry, piezoelectric and magnetostrictive. Both have the same functional objective, but the two types have dramatically different performance characteristics.

Piezoelectric Transducers have an assembly that is inexpensive to manufacture due to low material and labor costs. This low cost makes piezoelectric technology desirable for ultrasonic cleaning. For industrial cleaning, however, piezoelectric transducers have several shortcomings, the most common problem being that the performance of a piezoelectric unit deteriorates over time.  

Magnetostrictive Transducers are known for their ruggedness and durability in industrial applications. Zero-space magnetostrictive transducers consist of nickel laminations attached tightly together with an electrical coil placed over the nickel stack. When current flows through the coil it creates a magnetic field. This is analogous to deformation of a piezoelectric crystal when it is subjected to voltage. When an alternating current is sent through the magnetostrictive coil, the stack vibrates at the frequency of the current.

Blue Wave Ultrasonics Offers The Best Solution

The solution used in ultrasonic cleaning is a very important consideration. Chemical formulators are developing products that meet the demands of cleaning operations, yet are compatible with the health and well-being of society. Table 1 is a guide for the selection of appropriate cleaning agents for use with ultrasonic cleaning.

Table 1
Material of Construction Types of Parts Contaminants Suitable Cleaning Agent
Iron, Steel, Stainless Steel Castings, stamping, machined parts, drawn wire, diesel fuel injectors Chips, lubricants, light oxides High caustic with chelating agents
Iron, Steel, Stainless Steel Oil-quenched, used automotive parts; fine mesh and sintered filters Carbonized oil grease, carbon smut, heavy grime deposits High caustic, silicated
Iron, Steel, Stainless Steel Bearing rings, pump parts, knife blades, drill taps, valves Chips; grinding, lapping and honing compounds; oils; waxes and abrasives Moderately alkaline
Iron, Steel, Stainless Steel Roller bearings, electronic components that are affected by water or pose dryer problems, knife blades, sintered filters Buffing and polishing compounds; miscellaneous machining, shop and other soils Chlorinated-solvent degreaser (inhibited trichloroethylene, for example)
Aluminum and zinc Castings, open-mesh air filters, used automotive carburetor parts, valves, switch components, drawn wire Chips, lubricants and general grime Moderately alkaline, specially inhibited to prevent etching of metal, or neutral synthetic (usually in liquid form)
Copper and brass (also silver, gold, tin, lead, and solder) Printed circuit boards, waveguides, witch components, instrument connector pins, jewelry (before and after plating), ring bearings Chips, shop dirt, lubricants, light oxides, fingerprints, flux residues, buffing and lapping compounds Moderately alkaline, silicated, or neutral synthetic (possibly with ammonium hydroxide for copper oxide removal)
Magnesium Castings, machined parts Chips, lubricants, shop dirt High caustic with chelating agents
Various metals Heat treated tools, used automotive parts, copper-clad printed circuit boards, used fine-mesh filters Oxide coatings Moderately to strong inhibited proprietary acid mixtures specific for the oxide and base metal of the part to be cleaned (except magnesium)
Glass and ceramics Television tubes, electronic tubes, laboratory apparatus, coated and uncoated photographic and optical lenses Chips, fingerprints, lint, shop dirt Moderately alkaline or neutral synthetic
Plastics Lenses, tubing, plates, switch components Chips, fingerprints, lint, shop dirt Moderately alkaline or neutral synthetic
Various Metals, plastics (nylon, Teflon, epoxy, etc.), and organic coatings when water solutions cannot be tolerated Precision gears, bearings, switches, painted housings, printed circuit boards, miniature servomotors, computer components Lint, other particulate matter, and other light oils Trichlorotrifluoroethane (fluorocarbon solvent), sonic vapor degreaser

Blue Wave High-tech Cutting-edge System Design

Industrial, heavy-duty applications require industrial, heavy-duty ultrasonic equipment for ultrasonic cleaning solutions. Other factors that need to be considered are cleaning solutions and temperatures, rinsing (with or without ultrasonics), drying, automation, and load requirements. Most manufacturers of ultrasonic cleaning systems will assist in these decisions and will offer laboratory services and technical expertise.

Contact Us

We take your privacy seriously. No spam.
By submitting this form I agree to be contacted by Blue Wave Ultrasonics via email or phone if provided. See our Terms and Privacy Policy.

Affiliations

The AIM Institute provides courses to help advance the injection molding industry, including our ANAB-Accredited Plastics Technology and Engineering Certificate Program, Mold Maintenance Courses, and Autodesk Moldflow Training Courses.

National and International companies trust BLUE WAVE’s commitment to adhere to the strict standards set by UL. We are a 508A Industrial Control Panel Manufacturer.

MoldTRAX provides intuitive software for mold technicians and toolroom managers and lets you gain control of your operations by tracking multiple assets including molds, dies, presses, and ancillary equipment.