Warning: Saw a shop in Tacoma running a 3/4 end mill at 10k rpm for aluminum

I was picking up a part from a vendor over there and watched their operator run a whole batch like that, claiming it was 'fine for roughing'. That's way over the recommended speed for that tool size and material in my book, and I'm surprised they haven't had a catastrophic failure yet. What's the fastest you'd ever push a tool like that in 6061?

2 comments

2 Comments

the_evan3d ago

I used to think you could push those speeds for a quick rough pass, but seeing a 3/4" end mill explode at 8500 rpm in a nearby shop changed my mind. The math might say it's possible, but the risk just isn't worth it. I wouldn't go over 6500 for a tool that size now.

singh.wren3d ago

I ran a 3/4" carbide end mill at 8000 rpm for years on aluminum, thinking the feeds and speeds charts were too safe. After reading @the_evan's story about that tool exploding, I completely recalculated my roughing passes. The idea of sending sharp metal shrapnel across the shop just isn't okay. Now I keep it under 7000 rpm even for quick jobs, because seeing is believing. Have you dialed back your speeds on bigger tools too?