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  for Metal Finishing since 1989
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High voltage micro-arc electrocleaning

1996

I know electrolytic cleaning is used in almost every metal plating line but my reading suggests that the voltages are invariably low, around 10 V or so, perhaps even lower. However I have a British patent in front of me which relates to a rather different electrolytic cleaning process. The patent was filed in November 1972 by M. J. Copsey and B. H. Wilby (1399710) and proposes a process which uses very much higher voltages and current densities. At low voltages the authors report a linear relation between current density and voltage (this they call the normal electrolysis regime) while at high voltages the current reaches a maximum,
then falls to a sort of plateau which they call the unstable regime. They propose a process which operates in this plateau regime which is at 130 V to 180 V. They claim that discharges (micro-arcing) through the layer of steam and hydrogen on the surface of the work do the cleaning.

My questions is (sorry to take so long to get to it!): Has any large, or for that matter small, scale application been made of such high voltage electrolytic cleaning processes in the steel or other metal industries? Has a commercial use been found for the type of process covered by this patent?

R.N.Stevens

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I cannot say definitively that the process has not been used, R.N., but I have never heard of it. Maybe someone else has a comment.

This inquiry brings to mind anodization of zinc, strangely enough: that is a process which offers absolutely unbelievable salt-spray resistance, but which has been very rarely actually applied. The reason seems to be that the people who would be expected to apply it, anodizers and platers, are accustomed to open, exposed, bus bars, and voltages of 18 V and below. Tell them about anodizing zinc, which requires voltages in the range you are speaking of, and they picture their open uninsulated bus bars running all over the plant, their regular methods, and their people--and they scream "Have you lost your mind?!"

The problem in having high voltage electrocleaning put into practice may be similar.

The people who might know would be the power supply (rectifier) vendors. See the banner at the bottom of the page for rectifier suppliers. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
1996