Hit a weird snag with my machine's feed rate on a batch of aluminum parts

I was running a batch of 50 aluminum brackets last week and kept getting chatter marks no matter what I tried. I was ready to blame the tool holder or the material, but then I remembered an old trick from a forum thread about spindle load. I dropped my feed rate from 40 to 32 IPM and bumped the rpm up by 500, and the chatter just vanished. Has anyone else had success playing with feed vs speed on thin wall parts like that?

3 comments

3 Comments

samrodriguez1d ago

40 IPM on thin wall aluminum? Man that is way too fast for that setup. I would have been shocked if you didn't get chatter at that speed. I still remember this one time I tried running some 6061 brackets at 38 IPM with a 1/4 endmill and the whole part was vibrating like a tuning fork. Dropping down to 28 IPM and bumping the rpm by 400 cleaned it right up though. It's wild how such a small change can make or break the whole cut.

theas281d ago

Respectfully, I gotta disagree here. 40 IPM on thin wall aluminum is totally doable if your machine is rigid enough and you're using the right toolpath. I've pushed 50 IPM on .050" wall 6061 with a 3-flute variable helix endmill and got mirror finishes no problem. Chatter isn't always about speed alone, it's usually a resonance thing with the whole setup. Your 38 to 28 IPM fix worked for your specific part and machine, but that doesn't mean it's a rule for everyone. Sometimes bumping the feed up actually breaks that harmonic vibration and quiets everything down. Different machines, different tools, different results.

elliot_roberts1d ago

Its the same thing with a car you gotta find that sweet spot where everything just stops shaking.