Switched to a 5-flute end mill for aluminum and got worse surface finish

I tried a 5-flute variable helix end mill on a 6061 part last week because everyone says they leave a better finish, but my surface came out rougher than my old 3-flute. The chip evacuation was terrible and I ended up with built-up edge on the last pass. Has anyone else found that more flutes isn't always better for aluminum?

2 comments

2 Comments

ericgonzalez15d ago

More flutes definitely doesn't mean better in aluminum, that's a common myth guys run with. 3 flutes give you way more room for chip evacuation which is critical with gummy 6061. Those 5 flute tools are really designed for steel or harder materials where you need more cutting edges to spread out the wear. Your built up edge issue is a dead giveaway that the chips are recutting and welding back onto the tool. Maybe try bumping up your feed rate a bit to make the chips thicker so they break better. And if you stick with 3 flutes, you'll probably get that nice mirror finish back without fighting chip packing all day.

karen_hart15d ago

yeah I dunno, is a mirror finish really that big a deal on aluminum anyway