Heard a new guy say 'speeds and feeds don't matter that much' today

I almost choked on my coffee when I heard a trainee tell our lead that feeds and speeds are overrated. Dude tried running a 1/2 endmill at 2000 rpm through some 4140 and wondered why it sounded like a dying cat. Has anyone else had to bite their tongue around fresh operators who think they know better?

3 comments

3 Comments

pat_fisher241mo ago

Oh wow, 2000 rpm through 4140 is brutal.

taylor.sean1mo ago

Pat, come on, 2000 rpm through 4140 is totally fine if you know what you're doing. You just gotta have the right tool and a decent setup. I've pushed way harder than that on similar steel and it came out clean. The real issue is people not respecting their feed rate or chip load. If you're getting chatter or burning up inserts that's on you, not the material. Plus a lot of guys here are running older machines that just aren't rigid enough to handle it. Put some good coolant on it and let the tool do the work and it'll sing right through.

roberts9529d ago

Shoot, Pat's got a point actually. I don't care how good your setup is, running that fast through 4140 is just asking for trouble. I've seen guys try it with some fancy coated carbide and it still ends up looking like a tortured mess. You're either getting heat checking or the tool screeches like a dying cat. The only time I've seen it work is if you're hogging out something super shallow or you have flood coolant dumping like a fire hose. Otherwise its just a recipe for buying new inserts every five minutes and cussing at the machine.