304 SS slots

[#Rekd™]

Hi,

 

I am trying to machine .240 wide slot x .080 deep x 7" long in 304 SS. I am using a 4 flute solid carbide endmill but it keeps chipping.

 

My depth of cut is .025 with a .005" finish and the speed is 2000 rpm with a feed rate of 3.

 

Am I doing something wrong?

 

John

[Rick Henrickson The Boeing Co.]

do you have any corner rads on the tool?

 

150 sfm .0015 feed per tooth

[lynn vandike]

slower rpm. you have to let it take a cut. if that doesn't work try less depth of cut. 1000 rpm is a good start.

[#Rekd™]

Hi,

 

No rads!

 

John

[Storkman]

What size is the cutter?

[Rick Henrickson The Boeing Co.]

lynn is right

150 sfm = 1146

feed would be 6.8 for the 4 flute

 

smalll rads and coating would help

[Rick Henrickson The Boeing Co.]

your right stork I was thinking it was 1/2 inch I brain farted

[#Rekd™]

Hi Cascadeclimer,

 

How are you calculating this?

 

Is the Rpm not (Cutting speed x 4 / diameter)?

 

and the feed (feed per tooth x diameter x #of teeth x rpm)?

 

Am I out on this?

[Rick Henrickson The Boeing Co.]

I brain farted I thought it was a 1/2 inch because that is what I was doing right then on my file

 

so 150 x 3.82 / (tool dia) = rpm

 

then 4 flute x .0015 = .006

 

multiply that by your rpm

 

sorry about that

[terry5357]

are you ramping into cut, if so use long ramp length. this will put less load on the back side of the cutter. straight plunge is not what I would do

[Jack Mitchell]

Matl: 303SS

Slots are .192 and .235 respectively.

3/16 Slotdrill full depth .125

 

.02 Axial cut leave .003 radial for finishing with different cutter.

 

4800rpm .0036"/rev or 17.28"/min

 

The above gets me through appr. 2000 slots 5/8" long and has consistantly for 12 years.

 

Carbide and SS don't get along very well IMHO.

 

Regards, Jack

[Chris Rizzo]

what kinda cutter Jack? That's 'bout 230 sfm there.

[Storkman]

quote:

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Carbide and SS don't get along very well IMHO

---

Whoa Jack.

 

All we run is stainless and carbide. 300 series is a little touchy, but I will run 400 series all day with carbide. 300 is tricky no matter what you use. Indexables tear up stainless if you get the right grades and sfm. AJX feedmills will fly.

 

Indexable:

I run 450 sfm in 400 series to rough and 660 sfm to finish, and I don't back off much for 300 series.