Cleaning aluminum extrusions
I manage the Faculty of Science Workshop at the University of Calgary.
Much of our work involves the use of Aluminum. Over the years we have set up a small anodising operation. While our techniques of hand washing/scrubbing of parts, and hanging them in the acid bath by means of hooks made from aluminum welding rods provide us with a 99% success rate, the process is very time consuming and thus expensive.
We would appreciate any advice on preparation and cleaning techniques used by others and any information about supporting and maintaining good electrical contact.
I have just found this page today, Thanks
University of Calgary
We use titanium hangers or racks for our anodizing operations. Also, we use a non-etch chemical cleaner for aluminum, followed by a nitric acid de-oxidation, then anodize. For heavily oxidized aluminum that does not respond to this process we include an immersion dip in nitric/hydrofluoric acid. This is a hazardous solution but quite effective at heavy oxide removal on aluminum.Robert D. Mikkola
aerospace - Oak Ridge, Tennessee
I am sorry to say I have nothing to contribute towards your problem, but I do have one of my own. I am putting a thin chromate coat over 380 aluminum castings and am finding a very small but problematic amount of copper on the castings after plating. I am also having problems with consistent coating. Would you have any experience with such a problem or know of a good text on chromate conversion coating? I am also in the need of a good monitoring method. I am currently using the ASTM spot test to some success. I have heard of ESI but don't know if it would be good for such a thin coating (about 150 A).Dr. Joe Hanke
engineer - San Jose, California
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