I always thought running aluminum dry on our Haas VF2 was fine, just a bit more cleanup. My old boss in Dayton said coolant just made a mess. But last month I had to run 500 pieces of 6061 with tight pockets. The chips welded to the tool every time, ruined three end mills. I switched to a light flood of Trim Sol and the difference was huge, no welding and a way better finish. Anyone else run into this on longer jobs?
Man, my buddy tried to skip coolant on his home shop mill last year. He was making a simple aluminum bracket and thought he could get away with a quick spray of WD-40. Ended up with a solid blob of welded aluminum stuck to the end mill. Had to stop everything and spend an hour picking it apart. He never tries to cut dry now, even on tiny jobs.
Oh man, tell me about it! I learned that the hard way too. Ran a small batch of parts dry once and it was fine, so I figured a bigger job would be okay. Big mistake. The chips just gummed up everything, killed the finish, and I was babysitting the machine the whole time. A little flood coolant makes aluminum cut like butter and washes the chips out. Your old boss was dead wrong on that one.