Preventing rust or oxidation of parts after an ultrasonic cleaning process is rather common. Many parts which are ultrasonically cleaned are manufactured of steel or other metals which oxidize to produce an unsatisfactory finish after the cleaning cycle.

Parts which are cleaned ultrasonically are more prone to “flash rusting” after completion of the cleaning operation since all protective oils or coolants have been removed, thereby exposing the bare metal to oxygen. Preventing rust is therefore an important concern. It is common to find a light layer of rust on the surface of un-protected steel components. Since the ultrasonic cleaning process is so efficient, it removes all of the oils from the surface down to the microscopic hills and valleys found on the surface, making the material more prone to rusting. Fortunately, systems can be engineered to include Rust Preventative Dip Tanks which are typically used just prior to the drying operation to prevent rusting for 3 weeks to 6 months, depending upon the environment that the parts are stored in, and the type of rust preventative dipping agent in use.

Many rust preventatives, or “RP’s” coat the parts with an oily material to prevent the material from being oxidized. However, this defeats the ultrasonic process as a whole since you are essentially re-contaminating the parts with oil.

Another alternative commonly in use is to utilize an RP which does NOT leave an oily coating on the surface of the material, but rather temporarily passivates the surface to prevent oxidation. These RP materials can typically be painted or coated over, and does not leave appreciable residues behind.

Zenith Ultrasonics can incorporate rust preventative dipping tanks into any multi-stage cleaning system to prevent flash rusting, or long term rusting, using either a coating RP, or a passivating RP.