David Boyer
Plastic
- Joined
- Mar 16, 2007
- Location
- Hastings MN
Hi, My shop uses carbide end mills almost exclusively and I think most machinists here have just got it in their heads that carbide is always going to be the fastest and most efficient way to remove material.
We do a lot of prototype work and I primarily run a 2 axis CNC mill that is a retrofit Sharp mill. With the 2 axis, I am the go to guy for quick turnaround modifications and onesy twosy parts where, by the time a 3 axis guy has his tools loaded and the programming done, I have already completed the part.
Anyway, my machine is limited to about 3500 RPM and is not the most rigid machine in the shop. It get's the job done, though. It is more rigid than most would think. So here's the deal: I almost always use carbide end mills but am almost NEVER running them under ideal conditions. Most of the time the RPM is too low, and there is never going to be perfect rigidity. Because of this I have a tool box full of dull, chipped carbide end mills. Even though I try to keep sharp finish end mills just for finish passes, I still end up with a bunch of chipped end mills over time. Eventually I send them out for regrind, but nobody seems to like to use regrinds.
So the other day I noticed that my boss had a few 1/2" cobalt 4 flute, fine tooth, coated (TiLN I think?), roughing end mills on his desk. I took one to try out.
I cleared a 5" diameter hole in 1018, 5/8" thick. I started with a 17/32" start hole and went all the way through the part in one shot. I used .040 width of cut and ramped up to 42 IPM. I ran about 2000 RPM I think. It cleared the hole in about 10 minutes. The end mill was not in the least bit warm afterwards. It cut effortlessly and I think I could have used a much heavier cut.
The end mill showed no signs of wear at all. I have used it several times since and it still looks and cuts like new.
So have I been wrong to use carbide all these years? Is cobalt better when conditions aren't perfect? Also, most of our CNC machines are not the best machines in the world. We go through A LOT of carbide end mills. I've seen videos of super rigid machines machining parts with carbide at just incredible speed and I think "we could never dream of doing that!"
I have requested that my boss get a variety of cobalt end mills for me to try out and he is all for it. So am I on the right track?? Is cobalt often better than carbide??
Thanks for any opinions!
We do a lot of prototype work and I primarily run a 2 axis CNC mill that is a retrofit Sharp mill. With the 2 axis, I am the go to guy for quick turnaround modifications and onesy twosy parts where, by the time a 3 axis guy has his tools loaded and the programming done, I have already completed the part.
Anyway, my machine is limited to about 3500 RPM and is not the most rigid machine in the shop. It get's the job done, though. It is more rigid than most would think. So here's the deal: I almost always use carbide end mills but am almost NEVER running them under ideal conditions. Most of the time the RPM is too low, and there is never going to be perfect rigidity. Because of this I have a tool box full of dull, chipped carbide end mills. Even though I try to keep sharp finish end mills just for finish passes, I still end up with a bunch of chipped end mills over time. Eventually I send them out for regrind, but nobody seems to like to use regrinds.
So the other day I noticed that my boss had a few 1/2" cobalt 4 flute, fine tooth, coated (TiLN I think?), roughing end mills on his desk. I took one to try out.
I cleared a 5" diameter hole in 1018, 5/8" thick. I started with a 17/32" start hole and went all the way through the part in one shot. I used .040 width of cut and ramped up to 42 IPM. I ran about 2000 RPM I think. It cleared the hole in about 10 minutes. The end mill was not in the least bit warm afterwards. It cut effortlessly and I think I could have used a much heavier cut.
The end mill showed no signs of wear at all. I have used it several times since and it still looks and cuts like new.
So have I been wrong to use carbide all these years? Is cobalt better when conditions aren't perfect? Also, most of our CNC machines are not the best machines in the world. We go through A LOT of carbide end mills. I've seen videos of super rigid machines machining parts with carbide at just incredible speed and I think "we could never dream of doing that!"
I have requested that my boss get a variety of cobalt end mills for me to try out and he is all for it. So am I on the right track?? Is cobalt often better than carbide??
Thanks for any opinions!