I have milled 1/4 inch AL plate,6061-T6, for years to make tooling plates. Don't average more than one a month, however. I have always used ENCO cheap 2-flute end mills with WD-40 sprayed on when the chips start to weld themselves to the end mill. This is all with a manual mill, so I can readily see the problems.

I have never found a problem with the ENCO mills.

Paul