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-----Hardcoat anodizing for rip fences
I am having some rip fences for table saws fabricated by a machine shop. The bodies of the rip fences will be channels extruded out of alloy 6063-T6 aluminum and will have a 2" angle of alloy 6061-T6 welded at one end in a T-square configuration. The outer faces of the legs of the channels will serve as the guide faces of the rip fences. That is, the saw operator will slide pieces of wood along the faces. Will hardcoat anodizing be necessary for this application in which abrasion occurs due to wood rubbing on aluminum? Or, will some kind of "regular," organic type of anodizing provide sufficient abrasion resistance for my fences? Is hardcoat anodizing available in colors that last (one person told me that as hardcoat ages, it turns very dark and, therefore, black is the best color)? Is buffing/polishing required before hardcoating - since I've read that hardcoating results in a slightly roughened surface?
Thanks.
Larry LooWazee Products - Clovis, California, USA
2000
2000
I don't have the test data I would need to tell you that conventional sulfuric anodizing is sufficient, but that is the way I would lean.
Basically, as aluminum is converted to aluminum oxide, you lose transparency as the thickness increases. At the same time, any non-aluminum elements taking part in the reaction (silicon, copper) obviously cannot be converted to aluminum oxide but become discolorations. So the thicker the anodizing, the less clarity you will have.
The aluminum oxide probably does not change color as it ages, but even well sealed it will gradually get dirty and the tramp metals will discolor. 
Ted Mooney, P.E.
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