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Overheard a guy at the local shop say he never uses coolant on aluminum parts
I was picking up endmills at Midwest Tool yesterday and some old timer swore running dry on 6061 gives a BETTER finish. Has anyone else tried skipping flood coolant for aluminum and actually gotten good results?
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taylor_patel15h ago
Old timer swore running dry on 6061 gives a BETTER finish" - nah man, he's not wrong but you gotta be careful with that. I run dry on 6061 all the time with a 2 flute carbide endmill and get a decent finish, but it's not better than flood coolant at speed. The trick is you have to keep your chipload right and take light enough passes so the heat goes into the chip, not the part. @pat_roberts55 is spot on about rigid setups though - if your machine shakes at all you're just asking for built up edge and a wrecked part. I've seen guys try this on a worn out Bridgeport and just end up with aluminum welded to the tool after like 10 seconds. Flood coolant helps flush chips and keeps temps down way better than anything, so calling it "better" is a stretch. Maybe he meant "good enough" for roughing or one-off parts where you don't care about tool life. But for any real precision work, I'd rather have some coolant and less headache.
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morganmartinez22h ago
Yeah I saw a guy on Practical Machinist swear by it for roughing passes.
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pat_roberts5520h ago
Man I gotta push back on that one. Practical Machinist guys are great but they run stuff way different than most of us do at home or in small shops. I tried their approach on a few roughing passes with a cheap insert and it just hammered my tool holder way too hard. Maybe if you're running a 30 hp VMC with flood coolant and rigid everything it works fine but for a manual Bridgeport or a little Tormach it feels like asking for chatter and broken inserts. I'd rather take slower passes and keep things smooth than risk wrecking a part chasing their speed. Everyone's setup is different I guess but that method cost me a whole afternoon fixing a messed up shoulder.
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