Milling Inco 718 with ceramics? Any good results?

Wondering if anyone had good (relatively) experiences rough or semi-rough milling this type of Inconel (or really ANY "Super alloy") with Silicon nitride based (Sailon) ceramics. If so, what brand, grade, speeds and feeds, etc... Thanks in advance.

Jeff

I've never done it myself, but I have seen it in action in videos and at the machine tool shows. It seems the Greenleaf WG300 whisker-reinforced ceramics have the longest history in doing this, because I was working for Norton Company in a joint venture with TRW when they also developed a similar product. The trouble was that Greenleaf patent was still active and there were some "issues". That's over now.

I'd probably still go with the big knowledge base @ Greenleaf. I hear of people milling at 800 to 1200 sfm in 718. Not a long life, but better productivity than carbide for roughing. You still need to finish with carbide if you need small corner radius.

Good results!

I just spent 6 months machining nothing but inconel 718 with ceramics! Very strange, sometimes scary at first , but then like anything it becomes second nature. Like the previous reply, Greenleaf is the way to go! I don't recall the specific spds and fds, having machined everything but for the last year, but that will be easy enough for you based on greenleafs recommendations. It is awesome roughing with it, make sure as always that you have solid fixturing, then plow right through that baby. A good coolant will suffice, no need to flood it, tapering needs to be watched, but otherwise you can take huge depths of cut. We would routinely make a rough cut ( bumped up) and recut ( semi rough) then finish up with carbide. Seco is the best in my opinion. We used the greenleaf " button" inserts, which will amaze you with there durability, for lathe work, the square inserts are equally as good on a mill. After a while inconel will become easier then most materials for you to cut! Keep in mind this is a very temperature sensitive alloy, so finish with caution! Good luck!

I know that Greenleaf's WG300 is the best way to go, but I may only have real access to Sailon type ceramics. I was wondering if anyone had any experiences with those. Don't get me wrong, I DO appreciate almost any advice/info on the subject.

Thanks.
Jeff

YouTube - ‪High speed machining 718 Inconel‬‏

carbide at 960 sfm on 718

One other thing, I read in a Greenleaf brochure about WG-300 that you can use flood coolant and they actually recommend it. What about Sailon ceramics? I know that some ceramics won't tolerate it. Is the Sailon type silicon nitride one of these?

Jeff

NTK Ceramic Cutting Tools also make a very, very good whisker ceramic grade WA1 a competitor to WG300. Also a NTK grade called SX5 and SX9 (Silicon Nitride) the speeds for ceramics milling Inconel 718 are from 1700 SFM to 3000 SFM, .003-.006 IPT, .020-.100 DOC. SX5 is the tough insert for heavy depth of cut and SX9 is the harder insert for notch wear. WG300 and WA 1 are expensive SX5 and SX9 are a little more that half the cost. mail me if you want more info.

Ceramics for milling are awesome.

My experience was with A286. I took a roughing operation with carbide from 45 minutes to 45 seconds. 6000sfm, 11700rpms on a 2" cutter, feeds well over 200ipm. Its nasty, noisy, fire flying everywhere, its just violent.

I was running Kennatmetal KY2100's, I think that's what they were.

The thing with ceramics, everything is backasswards. If your blowing out a carbide insert, you slow it down, with ceramics, you speed it up. With carbide, you turn faster than you mill, with ceramics, you mill faster than you turn.

Its all about heat, ceramic doesn't actually "cut", it relies on heat. Most of your insert wear is going to happen on entering the cut, no heat yet. It basically plasticizes the metal, and then wipes it away. Too slow, the metal isn't hot enough, the insert isn't hot enough, total destruction. Too fast metal becomes liquid and everything goes to total shit.

Successful Application Of Ceramic Inserts : Modern Machine Shop

Here's a good article that helped me out.

What are you running this on, you really need a machine that can keep up. If it can't there's really no point. There are a metric shitload of forces involved. Thankfully I didn't have to pay for my ceramic adventure, it was a $13k spindle. 23k hours on it, they said it was time, but I'm pretty sure it was the ceramic adventure that put it over the edge.

Northy said:

NTK Ceramic Cutting Tools also make a very, very good whisker ceramic grade WA1 a competitor to WG300. Also a NTK grade called SX5 and SX9 (Silicon Nitride) the speeds for ceramics milling Inconel 718 are from 1700 SFM to 3000 SFM, .003-.006 IPT, .020-.100 DOC. SX5 is the tough insert for heavy depth of cut and SX9 is the harder insert for notch wear. WG300 and WA 1 are expensive SX5 and SX9 are a little more that half the cost. mail me if you want more info.

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SX5 was one grade that I had available to try. Haven't got to yet, but I will definitely get the chance before too long. I have certainly had good results with Kennametal's KY3500, in milling cast iron.

Jeff

Bobw said:

Ceramics for milling are awesome.

My experience was with A286.

Here's a good article that helped me out.

What are you running this on, you really need a machine that can keep up. If it can't there's really no point. There are a metric shitload of forces involved.

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What else is A286 known as? I can't remember.

Unfortunately running it on a Fadal 4020A. 2" facemill. I also need to give it a go in 316 ss. Seeing that 316 ss is almost like Inco's easy going cousin, it SHOULD work, right? Probably just wishful thinking on my part!

Jeff

jdj said:

What else is A286 known as? I can't remember.

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Nastinium? Unmachinabilium?

jdj said:

What else is A286 known as?

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INCOLOY. inconel's less pissy little brother. 26- 50+% nickel.

For the record, my ceramic adventure that resulted in a busted spindle was on a Mazak FJV. An absolutely rock solid, rigid, dead nuts accurate bridge machine. With linear ways.

I still love that machine and its going on 5 years I haven't even touched it. Of course she hasn't called me, but I've made a few things on my Fadals that she should have been able to do. Stuff that should have been made on her.

Also for the record, I'm a huge Fadal fan. Love the damn things. Bang for the buck. Not the most rigid machines in the world, not the fastest, put you to sleep on the tool change.

4020A, thats the linear way version. Thats a rare pup, put it in a museum, cuz nobody wants it, and the rest of them are dead. You may actually have the last one left.

Call GreenLeaf, awesome people and they seem to think you can run ceramics on a Fadal, and they'll even send you free cutters and inserts. Don't mention the A part.

Bobw said:

An absolutely rock solid, rigid, dead nuts accurate bridge machine. With linear ways.

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A bit of a contradiction there at the end.

Jeff

on the Fadal do you stick rages between the removable side doors where you empty chips and the solid cover, when it shakes and the removable side doors start to rattle. loud

Northy said:

on the Fadal do you stick rages between the removable side doors where you empty chips and the solid cover, when it shakes and the removable side doors start to rattle. loud

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AHHHH! They do rattle, don't they!?! I put duct tape on the edges for the same effect as the rags! However, cutting the iron is quite smooth, it's the SS that really causes the rattle!

Jeff