Ralph Clendenin, Machining Plant Manager Stahl Specialty Company Kingsville, MO 64061
Ralph asked what preventive maintenance steps are recommended to assure a long, trouble-free life of ultrasonic cleaning equipment. Ultrasonic cleaning systems range from single tank bench top units to systems with a dozen or more tanks or process steps and which include pumps, filters, conveyors, material handling devices, etc. This makes a single, all-encompassing answer to this reader's question a little difficult in a single blog. Instead I'll do it in several blogs over a period of time so that I can give the question the attention it's worth.To help me decide where to start, I took a little trip down to the Service Department here at Blackstone-NEY Ultrasonics and talked to our service manager, Dave Thompson, to learn what kinds of service issues his department sees most regularly. Ultrasonic Generators are, unquestionably, at the top of the list. The ultrasonic generator is the part of the ultrasonic cleaner that produces the high frequency electrical energy that powers the ultrasonic vibrators or "transducers" which deliver ultrasonic energy to the ultrasonic tank(s). An ultrasonic generator is comprised of one or more printed circuit boards with components that are sensitive to and may fail due to moisture, heat and/or corrosion. Every effort should be made to assure that the ultrasonic generator is maintained in an environment that is as dry as possible. Frequent inspection to insure that there are no system leaks and that all liquid shields and seals are in place and performing their job is very important to keeping the ultrasonic generator dry and healthy. If moisture is unavoidable in the immediate environment of the ultrasonic cleaner, moving the generators to a remote location where dryness can be assured is advisable. In most cases, ultrasonic generators can be located up to 100 feet from the ultrasonic cleaning tank. The use of properly rated and shielded coaxial cable is necessary to maintain the efficient transmission of electrical energy at the ultrasonic frequency to the transducers. In the course of normal operation, ultrasonic generators produce heat. This heat is removed and dissipated into the surrounding environment by a combination of heat sinks and fan(s). In order for fan cooling to be effective, there must be an adequate flow of cool, clean air. Access to the surrounding environment is essential. Since the air surrounding the ultrasonic cleaning system is not always as clean as the parts it produces, a particle filter is frequently incorporated in the generator cooling system. Failure due to generator overheating as a result of clogged air filters is at the pinnacle of Mr. Thompson's list of frequent failures. Second on the list of causes of generator failure is a buildup of dirt on the generator's internal components because the filter has been removed (presumably to eliminate the need for periodic replacement or cleaning). "Dirt," and especially the dirt found in most manufacturing environments, may be electrically conductive. High voltages within the ultrasonic generator are conducted by the accumulated dirt and cause short circuits which lead to failure. Frequent maintenance of the generator cooling system to assure that the fan is operating and that all filters are clean is a good way to prevent this major cause of generator failure. Clean, oil-free compressed air from a can or a blow gun can also be used to remove any accumulation of dust within the generator. Finally, is generator failure due to corrosion caused by the corrosive atmosphere in the area of the ultrasonic cleaner. Many cleaning chemistries produce corrosive fumes which, understandably, find their way into the ultrasonic generator and produce corrosion of metals which, like dirt, provides conductive paths for high voltage shorts leading to generator failure. If a cleaning system is known to use corrosive chemicals, locating the ultrasonic generators in a sealed air-conditioned enclosure is recommended. The equipment manufacturer can assist in the selection of an appropriate enclosure with adequate cooling. This blog has concentrated on measures and maintanance procedures that will assure long, failure-free ultrasonic generator life. Additional ideas for keeping your ultrasonic or other cleaning system healthy and happy will be presented in upcoming blogs.
- FJF -