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Chemfilm and hard anodize on mic 8 aluminum material
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(to provide context, hopefully helping readers more quickly understand the Q&A's)
For a quick intro to anodizing, including the usual process sequence including "etch" and "deox", please see "ANODIZING of ALUMINUM Intro & FAQs"
"Chem-film" is a synonym (mostly only used in America) for chromate conversion coating of Aluminum. Two commonly used trade names for the process are "Alodine" (Henkel) and "Iridite" (Enthone-MacDermid).
Q. I need to chem-film and hard anodize a complex piece with multiple threads and holes. the job was planned just as aluminum and so we have the typical deox and etch activation prior to chem-film and then we came across staining in the material. I looked at the drawing and it is mic 8 material. it seems that using scotch bright will fix the staining but it will take time. Moving forward on the rest of the parts what is the best activation and cleaning method for this material?
Tiffany Hernandez- Whittier, California
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February 2022
A. Hi Tiffany. I haven't heard of Mic 8 ... is it possibly a typo and the drawing was supposed to say Mic 6? Cast aluminum like Mic 6 has silicon in it, so etching should be avoided, and minimal deoxidizing should be done, probably with fluorides in the deox.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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February 17, 2022
A. According to my info, MIC-6 is a 7000 alloy (about 7040) but in the annealed condition. The problem, it's a cast material and a 7000 alloy. Due to the annealing, the plate is very low-tension for processing. Do not pre-treat with alkaline pickling, at most only very briefly. There are also corresponding documents from the manufacturer with information on anodization.
Joerg BeerliAluminium consultant - Hallau, Switzerland
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