I used to think a 0.005 inch tolerance on aluminum was no big deal

An inspector at the shop in Dayton told me I was letting parts walk out the door with chatter marks because my feed rate was too high for the finish pass. I dropped it from 12 inches per minute to 8 and the surface finish is way better now, no more callbacks. What's your go-to feed for a clean finish on 6061?

4 comments

4 Comments

wade2502mo ago

What tool diameter and stepover are you running?

mark_ward2mo ago

My buddy in Toledo swears by 6 IPM for a clean finish, and wade250 has a good point about stepover.

blair_nguyen2mo ago

My friend at a shop in Milwaukee had a similar issue with 7075. He found dropping to 7 IPM with a 3/8 tool and a light stepover made all the difference for his final passes. The parts just looked polished right off the machine.

pat78114d ago

That's a solid data point right there. 7 IPM on a 3/8 tool is pretty conservative but if it's giving that kind of finish, it's hard to argue with results. I've seen guys go even slower on the final pass, like 5 IPM with a tiny radial engagement, and the surface just comes out mirror smooth. The key is really that stepover, keeping it under 10% of the tool diameter for the last couple passes. It eats up more time but if you're trying to avoid a separate deburr step, it's totally worth it. I've got a few parts where I run the rougher hard and fast then drop way down for the finish and it saves me a ton of hand work later.