Ultrasonic Cleaners for the Manufacturing Industry

Zenith Mfg & Chem Corp.  85 Oak St., Norwood, NJ  07648-0412  800-432-SONIC (7664)  Fax:  201-768-6999

Most parts which are ultrasonically cleaned are manufactured of a metal of some kind.  Stainless steel, copper, brass, steel, and other exotic metals are perhaps the easiest items to clean since they allow ultrasonic energy to pass directly through the material.  This allows the cleaning of interior part areas.  A good example of this property can be found when cleaning metal tubing.  Metal tubes cleaned ultrasonically, for example, are cleaned on the inside as well as the outside, since the ultrasonic energy can pass directly through the wall of the tube and cavitate the liquid inside of the tube.    The interior channels of a plastic injection mold can be cleaned since the ultrasonic energy can pass through the metal of the object to activate the liquids which are present on the inside of the mold.

Although metals can easily be cleaned ultrasonically in most cases, the properties of each metal are different, and therefore will require different cleaning procedures to ensure success.

As with all aqueous ultrasonic cleaning operations, metal cleaning processes will require  3-processing stages; ultrasonic cleaning to remove the contaminants, rinsing in water to remove the detergent residues, and drying the parts to remove the rinse water.  However, additional steps may be required for processing different metals, or different chemicals will be needed in the ultrasonic cleaning stage to produce the desired cleaning results.

Newly manufactured steel parts are typically contaminated with metal chips and fines, coolants, and cutting lubricants.  These cutting lubricants provide protection against rusting.  However, during the ultrasonic cleaning process, this protection is removed, and rusting becomes a significant consideration.  As a result, the cleaning system purchased must be capable of protecting parts against rusting after the cleaning process, otherwise the parts will be contaminated with rust upon completion of the cleaning process.  To provide this protection, the process must include a rust preventative stage in addition to the standard 3 processing stages.  Typically, the rust preventative process will take place after the rinsing stage, and can be accomplished in a number of ways. 

An Aqueous Rust Preventative Dip will provide excellent short term (1-2 weeks) of rust prevention, and is composed of a water bath in which a small amount of aqueous rust preventative material is added.  These materials leave no residues behind, and parts can be painted, plated, or coated without having to remove the rust preventative material.  This method is by far the most preferred method of rust prevention.

For longer term protection, the rust preventative material must coat the parts with an oil-based material to prevent the parts from coming into contact with oxygen.  However, this may require that the rust preventative coating be removed, and parts re-cleaned, prior to any painting or coating operations, making this method of rust prevention less preferred in most cases.

Stainless steel parts are the easiest to clean, since they are not subject to rusting in most cases, and are highly resistant to chemical attack and cavitational erosion, which is damage caused by the ultrasonic action itself.  As a result, most stainless steel parts can be cleaned in systems which provide the standard 3 processing stages of ultrasonic cleaning, rinsing, and drying.

Parts manufactured of aluminum can be difficult to clean.  Aluminum is a softer less-dense metal which is highly subject to cavitational damage, especially if the parts are highly polished.  After only 2-3 minutes of ultrasonic cleaning action, highly polished aluminum surfaces will be damaged by the ultrasonic energy, which will show as small starburst marks on the surface of the material.  As a result of this damage potential, special equipment and procedures must be added to the process to prevent this damage from occurring.  Unfortunately, we can not provide details on these procedures on this web site, since this technology is somewhat proprietary, and the ultrasonic industry has made stealing ultrasonic technology from Zenith a standard procedure.

Aluminum parts are also very sensitive to chemical attack. Chemistries must be carefully selected to ensure that they provide the cleaning action required without producing chemical damage to the parts.  Other than cavitational damage and chemistry selection, the standard 3 processing stages of ultrasonic cleaning, rinsing, and drying still applies to the cleaning of aluminum parts.

Copper and brass will also require the standard 3 processing stages, but the chemistries used in the ultrasonic cleaning stage will typically be on the acidic side of the pH scale to address the oxidation that may be present on the surface.  Newly manufactured copper and brass material may not have oxidation, and therefore can be cleaned in less aggressive alkaline chemistries.  However, there are additional considerations which must be included to provide the desired cleaning results.

For example, if the parts require zero-residue cleaning results, it becomes very important to make sure that the final rinse bath is perfectly clean, and has no detergent in it at all.  If detergents are present, there is a good possibility that oxidation will be created after the drying process, and will show as dark spots on the surface of the material.  Ultra-pure deionized water will be required in the rinse stage to prevent this from occurring, and the system delivered should include automatic monitoring and rinse water purging equipment to ensure that oxidation will not be produced after the drying operation.

As you can see, each metal may require a slightly different process than the standard 3 processes of ultrasonic cleaning, rinsing, and drying.  This is the primary reason why Zenith offers multi-tank ultrasonic cleaning systems with different numbers of cleaning tanks.  Most metal parts cleaning operations can be accomplished with a Multi-tank Ultrasonic Cleaning System, and we suggest that you begin your search for equipment on this page.  Of course, if you only require the ultrasonic cleaning stage, a Table-top Ultrasonic Cleaner, or Single-tank Console may be the equipment of choice.  Whatever your requirement, Zenith can provide the equipment, and has the expertise to ensure success.

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Last modified: 07/31/06