Production Machining

MAY 2016

Production Machining - Your access to the precision machining industrial buyer.

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46 PRODUCTION MACHINING :: MAY 2016 PARTS CLEANING :: Efective ultrasonic cleaning is dependent on a number of factors, including basket size and tank dimensions. A Refresher Course on Ultrasonic Cleaning A close look at the intricacies of this technology helps with understanding how it is most efectively applied. U ltrasonic cleaning is widely accepted as a means of preparing surfaces for subsequent fnishing and processing operations. Sonic energy produced by industrial ultrasonic cleaners quickly removes contaminants from virtually any surface that can be safely immersed in a cleaning solution. Te challenge is selecting the correct ultrasonic cleaner, along with its accessories, cleaning solution formula- tions, and cleaning procedures to accomplish tasks in the most efcient manner. How Ultrasonic Cleaners Work Ultrasonic cleaners are ftted with transducers attached to the bottom and/or sides of a tank flled with the cleaning solution. Transducers are powered by genera- tors and cause the tank bottom to serve as a vibrating membrane at frequencies measured in thousands of cycles per second (kHz), sending sound waves pulsing through the cleaning solution. Tese waves produce millions of tiny vacuum-flled bubbles that shoot out a powerful jet of liquid when they implode. Te force of the implosions, called cavitation, lifts contaminants of workpieces. Shock waves produced by imploding bubbles are discontinuities in pressure and may be on the order of 15,000 to 150,000 psi and at temperatures of 5,000 to 10,000°C (~9,000 to 18,000°F). Yet the process is so fast that sonic cleaning is safe when the correct frequencies are used. Ultrasonic Cleaner Frequencies Ultrasonic cleaners are available in several ultrasonic frequencies. Frequencies of 37 and 45 kHz are common and are ideal for the majority of cleaning tasks. Low frequencies such as 25 kHz produce (relatively) large cavitation bubbles that implode more violently against surfaces than smaller bubbles produced at higher frequencies. High frequency cavitation bubbles are better able to penetrate and assist in cleaning small openings and blind holes. Te approximate bubble diameter can be calculated By Bob Sandor, Ph.D., Contributor

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