Need advice on machining Inconel

[robk]

Need advice on machining this part... The material is a Pratt & Whitney spec Inconel...This is some very nasty stuff that's about 40 Rockwell.

The machine is a vintage horizontal Mori-Seiki MH80 with max RPM of 3000. Recommended SFM for this material is about 80SFM.

There are 16 scallops around the part.

Climb milling a single cut with a solid carbide cutter from Iscar puts too much pressure into the part and "bows" it inwards. Not acceptable. Also the cutters don't last more then one scallop.

Tried depth cuts @ .070 a pass with 1.5" insert cutter (6 flute) from Iscar. Lasts only 1 scallop with the inserts burning up.

The Iscar reps. are not having much luck. They have been here for the last 2 days with not much help. I am sorry but at this time I don't have tooling info (except that at this time it is an all an Iscar project).

Any suggestions are appreciated regarding tooling selection as well as toolpaths.

Thanks in advance.

 

 

[Guest]

Rob,

 

In my experience with this stuff, a sulfer based oil, Hangsteferes {sp) is the only way to fly.

 

We used to use carbide roughing mills, not insert mills, 70 - 90 SFM is about it, .0015 - .003 CPT

[Guest]

solid carbb roughers slow and steady have been

the only way i have made headway in this stuff.

some aps insert mills work but dont think this would be one imho.

not sure if i see any problem with a conventional rough cut +.02 or so?? then climb finish. would that solve part deformations from cutter pressure?

 

think john hit it again with feed and speed.

[Zoober]

Inconel is not relly so hard, but very tough. It's the Cr & Ni (between 70-85% combined) that makes it so tough to machine. ditch the inserts like they say above, and run endmills slo-mo, like john says.

 

Inserts (ceramic) work ok in turning for thick wall, but don't work very well for thin wall stuff as inco moves so easily.

[crazy^millman]

Varamill or some other geometry like this is going ot be you best bet. SFM sounds spot on pln on plenty of endmills hear it getting dull pull it right then do not think it will make it to the end of the cut it will not.

 

All I will say is good luck.

[sspv]

give your sandvik rep a call they have a grade of insert for inconel, also kyocera has a good grade. we use the sandvik insert to cut inconel augers on our 4th axis with good success.

[Guest CNC Apps Guy 1]

For this application Inserts are the WRONG approach because of the (apparently) thin walls and material.

 

Hanita Varimills would be the far better choice in thsi situation IMHO.

 

HTH

[flatwoods]

Hangstafers +1000

I used to machine this stuff along with Hastelloy in high pressure valves. Slow RPM and a higher feed rate trying to keep the endmill under the chip as much as possible.

[robk]

Thanks for all the input guys...

The oil that is being used is Windsor 3310. I don't know anything about it, so I will have to do some research on that end...

For solid carbide cutters we have already tried Iscar's "Solidshred" as well as their "Finishred" series... I'm not sure what insert cutter got tried yesterday, but today they (Iscar) want us to try their HELI2000 inser cutter...

Thanks for suggesting Hanita's Varimill. We actualy have a pretty good selection of them in here and we just might have to use them.

I personally have never tried Kyocera, but I will look into it. As for Sandvik... We (as well as myself personally) tend to shy away from them, but definitely might be worth looking into.

Thanks again

[Bruce Caulley]

I am very surprised that you are having trouble with Iscar on this. I have seen some work they did on the same part from a Saab engine. Maybe the local reps aren't up to speed.

 

Bruce

[steve f]

I've machined Hastelloy C276 in the past which has some properties similar to Inconel. I found the biggest problem results from work hardening in the cut surface and edge burr which pretty much burns out the cutter in a short time.

 

Sharp is key, slow RPM and maintain a decent CPT. If it rubs at all, the cutter is done. Inconel is notorious for notching inserts in turning operations from the hard burr that rolls up. My recommendation would be an uncoated, high helix, multi-flute solid carbide.

 

HTH

[steve f]

...forgot one thing. High depth of cut with decent radial cut works much better than shallow depth of cut since the corners of the cutter just burn out too quick. Depth = diameter, 60% width, 25 SFM and full coolant flood worked well in Hastelloy...hopefully it'll give good results in Inconel also.

 

 

steve

[medaq]

I have always had really good luck with data flute endmills. something about them that has always made my hard machining easier. Had one guy not pay attention to his tool path, and cut right through a curt vice with out him even noticing.

 

Jim

[Fig sign]

Hanita Varimill would be my choice .

I never milled Inconel but milled Monel and it was great .

BTW I`ve testing now NEW Iscar MILL similar to Varimill on 17-4 PH cond. and it works great.