Summary for large bent anodizing Discussion
Anodizing a large, bent, awkwardly shaped piece is the core concern here: the questioner has a long one-piece aluminum computer frame, about 53.5" x 7.75" x 0.0625" and roughly 5.7 sq ft total surface area, but only needs one side anodized, colored, and sealed. The excerpt mainly presents the part size and shape challenge, noting the obvious difficulty of finding a tank or box that can accommodate a bent workpiece. Because the thread text provided does not include any replies, there is no documented advice in the excerpt about racking, masking, or process limits. The practical issue raised is whether such an awkward, large part can be anodized successfully when only one face needs treatment, and how to handle the geometry without damaging the finish or the part.
Q. Hello,
I am building computer and the top, front, and bottom of the frame are one piece of long, bent aluminum that I wish to anodize. The piece is 53.5″ x 7.75″ x .0625″, totaling about 830 sq in. or a little less than 5.7 sq ft. however I only REALLY need 1 side (so half of all those) anodized/colored/sealed. Now, barring the obvious mechanical difficulties of finding a properly shaped box (since the piece will be bent, it will end up shaped like this):
I’m wondering mainly if this piece is too big to work within the confines of safe, DIY anodizing. I was thinking 6 amps/sqft, at about 35amps and 15V(DC) for 2 hours–which by the 720 rule gives 1 micron of al2O3 on the surface. Is this possible? Is there a better way? Is this safe? I understand that my cathode will need to have ~3x the surface area and my connector wire will need to be very firmly connected to the inside of the 3 sided box shape, if anodizing something like this is even possible. I appreciate any help you guys can give.
Nolan Smith
– Nashville, Tennessee, USA
July 18, 2012
A. The problem with DIY anodizing, or most any other metal finishing process is that it is more complex than you might think.
You will need appropriate cleaning, maybe etching, and desmutting steps (with appropriate rinses) before anodizing, and then rinsing and sealing after. Each of these steps needs to be controlled as to chemical concentrations, time, temperature, etc.
And, of course you need appropriate disposal of the wastes created.
What you need done is not very difficult for a decent anodizing shop, but a can of worms for you.
Jeffrey Holmes, CEF
Spartanburg, South Carolina
July 20, 2012
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