Machining anodized parts or anodize after machining?
I have a part that's basically a block of 6061 AL, I want to engrave a logo on top and have the whole part anodized but the logo be in bare aluminum.
I have 2 options - anodize the part, then remachine the logo on the top cutting through the anodize, or machine the whole thing including logo, mask off the logo (maybe with some sort of paint that will hold up in the anodize process but can be removed later with acetone or something).
I'd prefer to machine right through the anodize because it will be quicker, simpler and less labor - but anodize is aluminum oxide which is basically sandpaper material... so... is that going to kill the milling cutters I use to engrave? Its not a tiny cutter - the logo "lines" are about 1/16th wide, so I use a pointed drill mill to engrave it. I just don't want to go through one mill for every 5 parts or something.
Opinions on the best method? I've turned anodized parts with no problems but never many of them. I need to do about 200-300/month of these parts.
Carbide tooling will machine anodized aluminum quite successfully, HSS will die within very few parts. We have a part that is done exactly as you describe; anodize and then engrave. We use a 1/8" 90 degree spot drill engraving about .025" deep for six characters about 5/8" high and then about 0.008" deep for about 50 characters 0.150" high. A single tool will complete 500 pieces without a noticeable difference in appearance.
Just a thought for an alternative is to laser engrave the logo. This works well for batches after annodizing. The cost of farming it out for laser engraving is probably less
and can give some alternatives to the detail, think silk screening.