Why does nobody talk about feed speeds changing with tool wear?

I was running some 6061 aluminum parts the other day and noticed the newer guys in the shop keep their feed and speeds the same all the way through a tool's life, even when it's been run for 8 hours. My old mentor used to back the feed down by about 15% after the first 2 hours to keep surface finish consistent and not burn up the insert. Does anyone else adjust their feeds as the tool gets dull, or am I just stuck in the old ways?

4 comments

4 Comments

henry_anderson546d ago

My first shop had a guy who ran the same 0.002 IPR feed on a 3/4 endmill for 12 hours straight and it worked fine. I've seen more setups go south from guys second guessing their feeds and cranking down too much trying to save an insert that's already done. The whole 15% rule sounds like an old wives tale to me. If you're dialing in your speeds right from the start, the tool wears evenly and you're just adding extra variables that are hard to track.

martinez.paul6d ago

Tool wear actually changes the cutting temperature curve, so adjusting speed instead of feed gives you more control.

jesse_smith106d ago

Wait, you're telling me that wear pattern actually affects the temperature curve that much? I gotta be honest, I used to be in the "just keep the feed steady and adjust speed when stuff gets hot" camp... but reading through this makes me think I had it backwards. I always figured speed was the main thing that drove heat, but if wear changes how the tool cuts and that shifts the whole temperature profile, then messing with feed makes way more sense for keeping things stable. That's a solid point, I'm rethinking my whole setup now.

taylor.brooke6d ago

Man, I feel this so hard. I used to be exactly the same way, I'd just crank up the speed when things got hot and hope for the best. Then I started noticing that on longer runs, the heat buildup would get weird, and I'd end up swapping inserts way earlier than I should have. It wasn't until I actually watched a worn tool cut under a microscope at a trade show that it clicked how much the wear changes the whole cutting action. You're not alone in rethinking this, it's a tough habit to break but once you start adjusting feed with wear in mind, things get a lot more predictable.