Letter 14061 Anodising assistance     1. I am required to sulphuric anodise a component with a surface area of approx. 7 sq mts. What is the best way of calculating how much power is required and if the existing rectifier will cope. Also is there an anode to cathode surface area ratio which must be taken into account. 2. Given the details above if the rectifier is 24V 1000A would this be capable of anodising the component at 7 sq. mts. surface area. Ian Beckwith - United Kingdom First of two simultaneous responses --   The 24 volts should be plenty. But I figure 7 square meters is 75+ square feet. That means your maximum possible current density would be 13.3 ASF. That's not enough. An anodizing rectifier should be sized for not less than 20 ASF. I wish the rest of the world would enter the 21st century and start using the foot-pound-second system :-) Ted Mooney, P.E.  finishing.com Brick, New Jersey Second of two simultaneous responses --   Ian, Your rectifier should be plenty if you are doing type II anodizing...you will not have enough volts to do type III. I don't have my conversion chart here at home ( I don't think we Americans will ever totally convert to the metric system).. but you want to anodize around 12-15 amps per square foot of surface area (for type II), so.. 1000 amps will be plenty. I'm not sure if you were asking what the work to cathode ratio should be.. but you want to keep it around 3-1 (work to cathode). Marc Green anodizer - Boise, Idaho   I somewhat stand corrected..thanks, Ted..I mis-calculated the meter-to foot number...however I believe his 1000 amps will BARELY be enough to anodize at 13 asf. Ya'll remember..back in grade shool..when they said "10 yrs from now, EVERY country will be using the metric system"...sheeesh..its been alomst 20 yrs.. and we STILL aren't there. Marc Green anodizer - Boise, Idaho   I design anodizing lines, but I don't actually run them, Marc, so I yield to your actual experience; but I would not design for 13.3 ASF--I think it's too iffy. Ted Mooney finishing.com Brick, New Jersey   You're correct, Ted..he would be pushing the limits..but..I guess I tend to look at things from a different point of view sometimes. I got the impression he had a job he needed to get done..and assuming it wasn't going to be an ongoing production job where the purchase of another rectifier could be an option..that he could "get by" using his current set-up. Sometimes.. ya just gotta wing it a little bit in our business..as long as quality isn't affected. And while running at 13asf may take a wee bit longer to get his desired thickness, I still believe he could achieve a quality product in the end. (Go St. Louis Blues!!) Marc Green anodizer - Boise, Idaho Dear Reader, please -- Post a question on a different subject.   Answer or follow-up on this subject (in non-commercial fashion).

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