Milling 4140 aneal

[Metric]

Hello Bro's,

I have a part 1.00" thick  (4.0" X 3.0" X 1.0"- 4140 annealed) need to mill out a lot of excessive stock on 40 tapper vertical machine. Please give me some advise on feed & speed. I plan to use 3/4" diameter, 7/8" LOC solid carbide  from Kennametal for it.

Thanks.

 

[jlw™]

I would use a 3/8 or 1/2 em and plan on at least one flip op to machine the warp out.  It won't be bad with 4140 annealed but depending on tolerance I'd plan for it.  Depending on endmill and toolpath any where from 300sf and .001ipt to 750sf and .005ipt.

[Colin Gilchrist]

For the .750 Endmill, you'll do great at 440 SFM, and 8% stepover (.060 radial). So that is:

2,345 RPM @ 37.5 IPM, is pretty conservative. That is .004 per tooth.

If you're feeling squirrelly, or really want to remove that material in a hurry, then I'd use 1% of the diameter, per tooth (.0075), which is .030 per revolution. That would be about 70 ipm.

Since your material is annealed, I think you can get away with closer to 70.

How are you planning to hold it on the second side? Soft jaws?

[Leon82]

Watch the roundness of that hole. I'm not sure what your tolerance is but it wont be round if the Vise is very tight

[nickbe10]

Any heat treat involved here? Do you have to machine it annealed?

If you have a choice "half hard" Rc 35 ish machines much better than annealed.........

[Metric]

Good morning all,

Thank you for inputs. The picture is top side that i plan to remove all material & finish top face and outer periphery included the boss. The 2 inner bores will rough out for last op to bore them, because to tight tolerance & squareness(+/-.0005"). Yes Colin the second op will finish back side (which is identical shape like top side) with soft jaw & plugs to prevent the collapse. (Customer wanted anneal not "haft - hard")

Hi Colin,

With 3/4 end mill can i go one shot full depth of cut ? (8% step over). Can i use coolant instead of air cool?(We don't have air blow system on our shop).

Thank you very much for help.

MDT

 

[SpacePilotPro]

From HSM advisor:  2300 rpm - 145 in/min - .012 stepover - 1.0" DOC