Many customers having purchased an ultrasonic cleaning system are disappointed when the parts they are cleaning are not consistently cleaned, especially inside detailed areas of the parts, or in blind holes and cavities!  In many of these instances, entrapped air in these locations has prevented effective ultrasonic cleaning of these areas.

Air entrapment is common when parts include several blind cavities or holes in different planes, when cleaning holes that are so small that liquid has difficulty filling it, and many other similar applications.

Ultrasonic cavitation, the scrubbing action which is produced by the ultrasonic cleaning system, can ONLY produce effective scrubbing action in liquids.  As such, ultrasonic cleaning will not take place at all in areas of air entrapment.  Although air entrapment is a hurdle which must be overcome for many cleaning applications, equipment design can play a major role in the system’s effectiveness when dealing with entrapped air.  For example, many of Zenith’s system designs includes oscillation of parts during processing.  This oscillation will serve to flush cleaning and rinsing fluid into air entrapment areas, thereby filling and draining these areas  during processing.  This can largely overcome air entrapment issues on many part designs.

Since one cannot change the design of the parts, the only solution include:

• Rotate or agitate the parts after they are submerged to release any air which may be trapped.  Continuous rotation is not always possible since parts damage will result. Part oscillation operations do an excellent job of flushing out blind holes and cavities to get these areas clean.
• Include manual rotation capabilities on the automation system:  Allows operators to rotate parts at some point during the cleaning and rinsing process to ensure that all areas are adequately addressed.
• In some cases, parts can be positioned so that blind holes or cavities fill and drain readily without trapping air.  This is achieved by positioning the blind holes in a near horizontal plane so that they can fill and drain when submerged or lifted from the bath.  In fact, this is a standard practice not only to prevent air entrapment, but also to reduce drag-out of detergent from the cleaning tank into the rinsing tank which may create water spotting on parts being cleaned.

Your Zenith salesperson will be able to assist you in testing your product for air entrapment.

Parts having Several Blind Holes or Cavities.

• Small-orifice Tubing or Holes which Prevents Water from Entering.
• Parts that are Stacked in Bulk May trap Air.

Zenith will assist you with your application to ensure that entrapped air does not interfere with cleaning of critical part areas.