Cavitation effects in ultrasonic cleaning baths

In this project, the effect of cavitation from aqueous ultrasonic cleaning on the surfaces of metal and non-metal sample coupons was studied. After twenty cleaning cycles, the mass loss from the aluminum coupons averaged 0.22 mg/sq cm surface area and 0.014 mg/sq cm for both stainless steel and titanium. The aluminum coupons showed visual evidence of minor cavitation erosion in regions of previously existing surface irregularities. The non-metal samples showed some periods of mass gain. These effects are believed to have minor impact on hardware being cleaned, but should be evaluated in the context of specific hardware requirements. Also the ultrasonic activity in the large cleaning baths was found to be unevenly distributed as measured by damage to sheets of aluminum foil. It is therefore recommended that items being cleaned in an ultrasonic bath be moved or conveyed during the cleaning to more evenly distribute the cavitation action provide more uniform cleaning.