Got bold and tried a .005 finish pass on a finish op last Friday

Thought it would give me a mirror finish on 6061 aluminum but instead I got chatter marks that ruined the whole part. Learned real quick that sometimes too light of a cut lets the tool rub instead of cut. Has anyone else found a sweet spot for finish passes on softer metals?

2 comments

2 Comments

ross.william18d ago

I mean maybe it's just me but that .005 pass is way too light for aluminum, it'll always want to rub like that.

evanpalmer18d ago

Light passes like that work fine if you take the time to dial everything in right. The tool needs to be dead sharp and the machine has to be rigid enough, but .005 in aluminum is actually pretty common for finishing work. The real issue is usually climb vs conventional cutting. Climb milling with a light chip load will absolutely rub and work harden the surface, but conventional cuts let the edge bite in every time. Run it conventional at that depth and youll get a mirror finish with no chatter. Plus aluminum's thermal expansion works in your favor here since the heat buildup from a light pass actually helps shear the material cleaner. Gotta match the feed rate to get a proper chip thickness though, thats where most guys screw it up.