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Trying to figure out amp hours to the rate of copper electroplated


I am trying to determine how many amp hours to plate a cylinder to achieve a required copper thickness . If I need .010 thousands copper my cylinder 34'' long 9.5'' diameter and is 1/3 submerged drawing 250 amps at 10 volts.

Daniel Bressert
Plating shop - Cincinnati, Ohio


The surface area of the cylinder is Pi x d x l or 1015 square inches, that is 7.05 square feet. If it's 1/3 submersed, the submersed area is 2.35 square feet, so your current density is 106 amps per square foot (sounds a little high).

But for the amp-hour calculation, the depth of immersion is irrelevant because you want 10 thousandths of an inch thickness on 7.05 square feet. You could proceed the hard way by finding the density of copper, calculating how many grams that volume of copper weighs, and how many gram equivalent weights that is, and applying Faraday's Law of Electrolysis. But the easier way is to go to the Metal Finishing Guidebook, where they've already applied all those conversion factors and tell you that it takes 17.8 amp hours per square foot to deposit 1 thousandth. So it will take 17.8 x 7.05 x 10 = 1255 amp-hours to plate your part. At 250 amps, that's about 5 hours. However, there are two assumptions involved. First that you're using acid copper (the copper is in the +2, cupric, state). Second that you are plating at 100 percent efficiency (no electricity wasted to evolving hydrogen instead of reducing copper). Acid copper plating is not 100 percent efficient, but it's probably darned close.

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


Sometimes I am surprised, how so-called specialists operate a galvanic shop, if they do not know neither Faraday nor the stoichiometric laws and further galvanic shop-relevant regularities.
How would it be with a forum for basic questions?

In this sense

Dominik Michalek
- Mexico City, Mexico


Hi Dominik. We welcome any and all questions of course. But a potential problem with a forum for beginners is that a beginner doesn't know what to ask and has no point of reference from which he can assign weight to things. Raw, random, self education is for brains of the caliber of Isaac Newton and Michael Faraday, not for most of us.

That's why tutorial style books and training courses are essential! The Garden State Branch of the American Electroplaters and Surface Finishers Society is making available their 22-chapter, 363-page "Electroplating Course Manual: Basic Practical Electroplating" for $30 (approximately the cost of printing). This manual, published in 1986, was the volunteer work of decades by Dodd Carr, Cy LaManna, Nabil Zaki, Larry Durney, Herb Tilton, Sal Mollica, John Kosmos, James Langan, Robert Duva, William Wittke, Bill Ohl, Warren McMullen, D. Gardner Foulke, Carl Buck, and Joe Gesumaria. Some of these names the readers will recognize as among the industry's luminaries.

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

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