PSA: I just switched from a 3-flute to a 5-flute end mill for finishing aluminum parts

My old shop in Tacoma always used 3-flute, but a new coworker showed me the 5-flute leaves a way better surface finish with less chatter. What's your go-to for aluminum finishing passes?

3 comments

3 Comments

spencer_moore391mo ago

The flute count matters less than your tool's corner radius for that final shine.

jackson.jenny1mo ago

Hey @spencer_moore39, I get your point about the corner radius being key for shine. But from my experience, the flute count really does change how the material comes off. A single flute leaves a cleaner finish on soft stuff like acrylic because it doesn't melt it as much. The radius helps, but you need the right cutter shape first.

reese8612d ago

The corner radius definitely plays a big part in that mirror shine, but I think the flute count changes how the cutting forces act on the part too. With a 5-flute, you get more teeth engaging the material at once, which can actually help dampen vibration if your speeds and feeds are dialed in right. For aluminum especially, I've noticed the 5-flute lets me push the feed rate a bit more without losing surface quality compared to a 3-flute. It's not just about the finish pass either, the roughing pass toolpath and stepover matter just as much for getting that final result.