Debate: Should you trust the old timer who says to skip coolant on aluminum?

I had a guy with 30 years tell me to run dry on 6061, swore it gave better finish. Next job it gummed up my end mill and cost me $200 in tooling. Who's had coolant save or ruin their cut?

3 comments

3 Comments

angela6871mo ago

Oh man I gotta push back on that a little bit. I mean yeah aluminum is sticky, but I've had times where running dry with a really sharp HSS bit and fast speeds left a mirror finish because you don't get any thermal shock from coolant hitting the part. Those old timers sometimes found weird tricks that worked on certain materials and setups even if it sounds crazy today. Your problem was probably feed rate or tool geometry more than going dry, not saying it's always a good idea but it's not always stupid either.

benclark1mo ago

Holy crap, 30 years telling you to run dry on 6061? That's wild. I'm honestly shocked he didn't warn you about the built-up edge that happens without any lube. Aluminum is sticky as hell, coolant is basically mandatory if you want any kind of tool life. I'd be pissed about that $200 too, sounds like his "secret trick" was just luck on a specific part.

carter.gavin1mo ago

Wait @benclark, you mean his "35 years of experience" didn't include a chapter on built-up edge? Sounds like he was just lucky enough to have zero problems until you showed up with a $200 bill. Gotta love those old school "tricks" that only work when the stars align.