Metal Finishing Guide Book

2013

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• Excess power has negligible value. A good manager should not pay for that. It will only serve to overheat the cleaning tank! • Excess cycle time is a waste of productivity. A manager should not stand for that. Remember: Generalized relationships and specific recommendations don't necessarily relate directly to actual performance data. MORE THAN JUST EQUIPMENT Performance of sonic-powered cleaning system, for a given set of parts, is related to much more than the choice of frequency and sweep rate, tank size, and power level. • Chemicals, and their concentration, affect performance. But there are other factors that can be significant, or not, which are not so obvious. Some observed by this author are: • Tank configuration — depth vs open area (more shallow tanks generally use power more efficiently), • Tank configuration — presence of unusual shapes where waves aren't reflected back onto parts, • Positioning (racking) of parts within the open volume of a tank, • Location of transducers within a tank (bottom, sides, etc.) • Operating temperature (an optimum is around 160°C , • Residual gas (air) content (there should not be any), • Water quality (reduced mineral content is better), • Smoothness of the part surface, • Excess fluid circulation can reduce effectiveness, • Waveform of the ultrasonic-produced pressure pulses (take caution over claims where non-sinusoidal waveforms are preferred), • Anything present on the part surface that would prevent it from being wetted (and submerged). • Accumulation of debris within the tank (clean tank; clean parts). It isn't that ultrasonic cleaning in static tanks isn't reproducible. It very often can be and is so. Ultrasonic cleaning is reliable very often. However, specific results (claims by single vendors of superior performance in unique applications) can often be difficult to reproduce in ultrasonic systems provided by other vendors. In other words, if a supplier can back up a claim with repeatable performance data with your parts, a manager should give great priority to that supplier in the selection process. Ultrasonic technology should be integral to — and designed for — a cleaning machine. This article has shown how a manager can be certain that is done. ABOUT THE AUTHOR John Durkee is the author of the book Management of Industrial Cleaning Technology and Processes, published by Elsevier (ISBN 0-0804-48887). In 2013, Elsevier will publish in print his two landmark books Science and Technology of Cleaning with Solvents [ISBN 9781455731312], and Handbook of Cleaning Solvents, (ISBN-13:978145573144) as well as a 4-part e-Book Design of Solvent Cleaning Equipment. He is an independent consultant specializing in metal and critical cleaning. You can contact him at PO Box 847, Hunt, TX 78024 or 122 Ridge Road West, Hunt, TX 78024; 830-238-7610; Fax 612-677-3170; or jdurkee@precisioncleaning.com. 76

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