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My old foreman told me to never run a 3/4 inch end mill over 2500 rpm in aluminum
Honestly, I thought he was just being overly cautious. So on a job about six months ago, I pushed a similar tool to 3200 rpm thinking I'd get a better finish faster. Ngl, it worked for maybe five parts before I heard a nasty screech and saw the flutes were completely welded up with aluminum. The whole spindle had to come down for cleaning. He was totally right about the heat buildup. What's the fastest you guys will run a 3/4 carbide end mill in 6061 without coolant?
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sagen364mo ago
That line about "the old rule about heat is definitely there for a reason" really hit home with me. I used to think old timers were just stuck in their ways, you know? But after my little experiment at 3200 rpm ended exactly like your buddy's - except I caught it before it welded solid, but the aluminum was already sticking bad - I realized they'd learned that lesson the hard way so we wouldn't have to. Now I keep my 3/4 inch cutters at 2200 rpm max in 6061 dry, and it feels a lot better than explaining to the boss why the spindle needs new bearings.
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tarahart5mo ago
My buddy tried pushing a 3/4 inch tool to 3000 rpm in dry aluminum once. He ended up with a solid aluminum slug where the flutes used to be. That old rule about heat is definitely there for a reason.
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