Help with shear cam 4140

[EazyE]

the slot is .625 deep by .803 wide in 4140 stainless

I have a altin coated .500 4fl .031 corner rad endmill .750loc. Since we mostly cut aluminum and plastics here stainless is a little nerve racking. Would anyone be willing to chime in on some cutting parameters to get this job done I would be greatfull. (machine limited to 10,000 rpm 200.ipm)

 

Thank You...

 

 

[Lars Christensen]

I assuming this is just a one piece deal?

1/2 4 flute carbide cutter~0.100 step down~full with of cut~flood coolant on~

 

my starting point in that material would be.

181SFM

.0012CPT

 

1383rpm @ 6.675ipm

[chris m]

4140 is Chrome-moly steel, not stainless; what is the hardness condition? I think that Lars is pretty close, on the conservative side unless the thing is pre-hard. I think you'd be better off with a smaller endmill, but you have what you have.

[EazyE]

Lars, Actually I have a half dozen of these to make.

 

Chris thanks for the correction. And from what I can gather it is case hardened Nitride .003/.003 deep.

 

Will this require change from what Lars stated?

[chris m]

That's not much of a case, but nitrided is probably pretty hard. If you get under the case [which you certainly would if it is only .003 deep] on the first pass you might be OK, but you might get a DOC notch on the endmill from the case so keep a watch for that. I'm no hardmilling expert but I think that you'd want to go with less axial DOC and a higher feed with air blast and not coolant; when the California hardmilling boys get to work they may have better advice.

 

C

[EazyE]

Well here we go.....

 

Thanks Chris..

[taperlength]

I'm guessing it gets hardened after machining.

[EazyE]

your guess is correct. I was not sure this morning.

I have cut one out of 6 with a perfect outcome.. Endmill still looks brand new. I love this stuff..

[Lars Christensen]