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Would you use diamond tooling for nickle based alloys?

Pitglc

Aluminum
Joined
Jul 21, 2006
Location
Mass
We are about to start a huge production run of a piece made from the material MP35N- Ni35 Co35 Cr20 Mo10.In my experience I have always found solid carbide tooling and the right speeds and feeds combination to be the ticket to machining materials of this type. However our engineers would like to approach this using diamond coated tooling to machine this material and I am not so sure about this.The piece is very small has a thin wall and very tight tolerances. .04id x .05 od x .135 long and we have to make 10's of thousands of them. This will be done on a swiss machine. Will diamond tooling be the approach to take to achieve optimum tool life and tolerance control with this type of material or is carbide the way to go? Thoughts and suggestions? Thank you in advance
 
Diamond tooling only for non-ferrous materials. Anything else will cause rapid deterioration of you diamond tooling.
 
PCD would probably work better in this application than diamond coated anything. Diamond coating will not work on sharp inserts so there has to be a small radius which will work against you big time. If you use diamond coating, your inserts will flake and fail early.

Paul
 
Last on my link - FYI 1%

The second link in #7 lists it as a "steel alloy", but it's wrong - any remnant iron is a contaminant, it's properly a Super Alloy.

It's the chemical reaction of the material at temperature and pressure that makes the material either a good choice or bad one for diamond tooling use. If the material has high-solubility with carbon it's likely to erode the diamond as it cuts, so ferrous-based materials aren't a good choice with diamond tooling unless cutting processes keep things cool.

I'd be looking at using a two-step process here, roughing the rod stock with carbide (and frequent tool changes to maintain sharpness), then using a pinch turning/boring setup with sharp CBN (or maybe ceramics) to finish the diameters.

Maybe laser-cut strip, roll, laser welded rings? Could be vastly cheaper at high quantities.
 
Coated is no use, but im willing to bet PCD or maybe even mono might be a good fit, your low iron and IMHO at thoes diameters i doubt your going to spin it fast enough for heat to be a issue any how, Diamond cuts steel great, just have to keep the surface being cut bellow 700C and it just cuts and cuts. Go too fast and get any real heat and the diamond just dissolves into the steel. Would imagine some kinda coated carbide would help on the drilling front, if nothing for the slicker surface.

Other option for the od might be to just grind it with a CBN plated wheel in a live tool if you have the space to swing one large enough to get a decent SFM.

Either way i hope you have factored in how to deal with the cobalt contamination in the coolant. because this just turned your coolant sump into hazmat. Mist collection is whole nother issue too. Carbide bob has a website - links too one with some great info on this issue.
 
My specs show 1% iron.

Ughh ...

OK, so it probably has a bit of Si, maybe some C, some Mn, and who knows what other atoms were floating around when they did the melt. Notice the min % for Fe -- 0. Any Fe in it is an impurity, not part of the desired metallurgy.

Regards.

Mike
 
My specs show 1% iron.

Iron or not, diamond turning is not recommended for nickel nor molybdenum and MP35N seems to be high on both.

Nevertheless might be worth a try if you have tens of thousands to make...

how bout PCBN (polycrystalline boron nitride) and nickel-cobalt superalloys??
 
Answering my own questions:

PCBN turning of nickel superalloys seem to be pretty much still academic interest but Seco has specific grade:
Seco Advanced material Expert: Secomax™ CBN17, designed to be the 1st choice in continuous semi-finish and finish turning of hardened nickel based superalloys

+1 on PCBN. It is not diamond, but it's what I would have looked into for turning any hard alloys. It doesn't do well on interrupted cuts. But still miles above carbide on hard stuff. Been out of the biz for a while, so there may be new materials that are better. But I was surprised at how long it keeps an edge.


Best Regards,
Bob
 
Is the stuff you are machining already age hardened? Is it the 260ksi stuff at like 54 HRc? Most Inco people complain about machining is around 180ksi! Good luck drilling it! I'd start with CBN and plan on sharpening it after every couple of parts.
 
The problem you have at these dia is not how hard the material is but how sharp a tool you need to be able to cut it and not simply destroy the part with those forces, Can you get a truly sharp CBN edge?
 








 
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