1/8 EM in 4140A, drill corners or not?

[honeybunches]

I have an inner profile that requires the corners be finished with an 1/8" EM. Material is 4140 Annealed. I have had plenty of problems trying to cut steels with 1/8" EMs. I think I drilled the corners before with 1/8" EM to reduce the load in the corners but it wastes a lot of time.

 

It is programmed right now to do full depth (.300) and run multi passes with about 15% radial engagement. I would prefer to remove the drilling unless absolutely needed. I am sure I could add passes but at some point, it started to make more sense to drill since that is where the tool would break, in the corner.

 

edit: My error. I apparently screwed up when naming the drill operation. As I decided to just plunge mill the corners with the 1/8" EM, I realized I already thought to do that last time but named it "drill" instead of "plunge mill". We should be just fine with this in this case. roughly a 30% engagement in the plunge. Notes say it worked fine last batch.

[GoetzInd]

Try dynamic area toolpath with 6% step over full depth and bump up the feed. The new 2d highspeed paths are your friend in these situations.

 

Mike

[K2csq7]

and run multi passes with about 15% radial engagement

 

+1 to Dynamic... you think your multi-passes are giving you a 15% radial engagement, but your pretty much burying the tool with the old 2d toolpaths...

use Dynamic and you will NEVER look back.

[honeybunches]

Thanks for the heads up guys. Not to seem pessimistic but I have just never had good luck with radial feeding with small endmills. I try to plunge where I can to get rid of some material. In this operation, there is only about 30sec of work for this EM. Anyone want to post a pic of what an optimized corner clean up would look like? I also need to feather it in in which I typically just use lead in/out and adjust to make a nice transition.

 

When I way 15% engagement, that is measured in verify in the corner. However, I realize that when the tool turns, you effectively double that engagement for an instant when changing direction.

[Izzzy]

Dynamic toolpaths are the way to go, I’m cutting 316 SS .250 deep .015 steep over with a .140 diameter 4 flute EM 15000 RPM 100 IPM. They cut for days.

 

the tools last for days that is.