Thanks to Pete C's advice, I am milling aluminum with HSS end mills.
These are Interstate end mills that Enco sells for $2.99 a piece.

I have to say that they work nicely, at 12 IPM, 2000 RPM, 2 flute,
1/4" diameter of end mill.

I am making those aluminum turner's cubes, which is a process that I
automated, so it takes me no time. All my friends want them.

Right now I am using depth of cut that is 1/3 of the end mill
diameter, and I am wondering if perhaps I am short changing
myself. Can I use depth of cut that is 1/2 of diameter? 1 diameter?
This process involves both slotting, as well as side milling.

i