I typically use 4 flute cutters for almost everything because thats what I have, but at work we use a lot of 4 flute cutters for steel and stainless, depending on the aluminum jobs but the main aluminum job we do we use a 3 flute 1/2" coated carbide that we run at 60 or 80ipm and a 4 flute 1/4" em that we run at 40ipm at .25" depth It leaves a really nice finish. this is all at 6500rpm. At these speeds and depths we are at the edge of breaking things
theres one of these 1/2" 3 flute carbides laying around that aluminum is completely melted to, musta forgot coolant
as my boss always says, "push it till it breaks, then back off a little."
Jon