I posted this in the "metal working machines" forum but I think this forum is where it belongs.
I am trying to engrave our company logo on a part that is made of billit 6061 aluminium then black sulfuric anodized. The anodize is chipping, I tried using a carbide engraving tool 1 flute 60° pointed tip, then a .06" radius tip 3° taper 3 flt carbide end mill I am cutting .01" deep. Spindle speed 12,000rpm I have tried slowing down the feed rate but that doesn't change the chipping. Any ideas?
You may have continual trouble with the anodize chipping. The anodizing process forms aluminum oxide. The oxide build up grows from the surface as well as penetrating the surface. This oxide build up is brittle which is the reason for the chipping when you engrave. There is no way to make the surface less brittle as it is chemically different from the substrate aluminum. When we do not want a particular area of the part to have anodized we stop off by painting. We also use different abrasive processes to finish areas which have been anodize. Hope this was helpful