Tried running the same part with a 3-flute vs a 4-flute endmill last week

We had a job for about 500 aluminum parts that needed a deep pocket. I ran the first 50 with a 3-flute, like I always do, and it was okay but the finish was a bit stringy. My lead told me to try a 4-flute for the rest, and the difference was crazy. The 4-flute gave a much cleaner finish and cut about 15 seconds off the cycle time per part. Has anyone else found a case where switching the flute count made that big of a change?

4 comments

4 Comments

dakota4153mo ago

Yeah, that checks out. Had a similar thing with some delrin parts needing a tight slot. Used a two flute forever, but it would chatter like crazy at full depth. Switched to a three flute on a whim and it just glided through, no more noise and the walls looked like glass. Sometimes the extra flute just grabs the material better.

ellioth373mo ago

Nah, more flutes just means more heat.

sage3083mo ago

Ever wonder if the tool rep just makes this stuff up? I had a guy swear by a five flute for aluminum roughing once, said it was the future. Tried it and it sounded like the machine was having a panic attack, had to go back to a three flute and eat the time. Maybe @dakota415 is onto something with that extra flute just working better in the cut sometimes, but it feels like a guessing game.

robin5911mo ago

Haven't we all learned that lesson the hard way? I've been doing this work for over twenty years and I still get burned by trusting a rep's word over my own gut. For aluminum roughing, a five flute is just asking for trouble unless you have a really rigid machine and a lot of horsepower. I stick with three flutes for most aluminum work, but I keep a two flute around for those thin wall parts where chip evacuation is the main concern. That delrin story rings true too, sometimes the flute count matters more for how the chip comes out than for cutting speed. It's not a guessing game, it's just a matter of matching the tool to the specific cut you're making.