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Facing Titanium

realityrat

Plastic
Joined
Jun 5, 2020
Hi everybody, thanks for taking the time to read my post.
I have to face mill 10"x10"x1" 6Al-4V titanium plates for use in an EOS 3d printing machine. The goal is just to get a flat surface within .001". I'm using a 7 flute carbide (GMS2 Coated)3/4 dia Bull nose Gorilla end mill with .09" rad. I've side milled a lot of titanium but I've never had to mill a plate flat, can somebody help with speeds and feeds and maybe any suggestions on cutting methods? I have a program with a trochoidal pocketing toolpath to keep cutting pressure consistent with a helical entry motion but again I'm new to face milling titanium. Thanks in advance, I do appreciate any and all suggestions.
 
It's frequently said that cutting Ti with a bare carbide cutter is better due to the sharper edge, and that you just have to accept more frequent regrinds and change-outs. Some work has been done using PCD, but that's doubtless a trial and error process to get right.

What's the condition of the plate? Is there any scale or other stuff that would complicate cutting? Is the printer a DLS or ? If so, is the workpiece WEDM'd off? And what machine is doing the cutting?
 
The plate is clean, after printing the part is sawed off and a little of the base is left on the plate. That is ground down with a cutoff wheel and the plate is resurfaced for the next printing job. I'm new to this metal printing so I'm not sure how much heat if any is transferred to the plate during the printing process.I tried using a 3 inch face mill but it seemed to smear the chips and didnt produce a good finish so the 3/4 dia. 7 flt carbide gorilla end mill was recommended but all the info I can find is about side milling and slotting. Since I'm just surfacing the top of the plate I'm only removing between .01"-.03" of material I'm not sure if the SFM and chip loads used for side milling would apply. I'll be machining the plate in a Haas VF4 SS.
 
I'd suggest getting a uncoated mill with a very small corner radius, like .020". Multi-flute is good, short, stiff holders for stability. Try 150sfm to start with ~.003"/tooth feed and see how it works for you with a 3/4" tool. These should be conservative, but YMMV. If you like how it cuts get more tools and have them resharped on the ends only before dull.

Climb mill, I think it's better to go extents inward if facing (Y5, Y-5, Y4, Y-4, etc.) rather than back and forth from one edge. Maybe 60% overlap, but play with this to se what gives best finish and time.

Let us know how it goes. I'd try to take .010" off at a time, save the expensive plate if possible G2 or G5 Ti?). Watch for bowing, may become an issue especially as the plate gets thinner.
 
A face mill would smear because the inserts almost always have an edge prep that makes them unsuitable for Ti. Also, 3" may be too large for a Haas, as it lacks stiffness. Stick with endmills for now.
 
Just finished cutting the plates. Ended up with 300 SFM and about .003" chip load with a step over of 60%. It worked great. I think I could've went more aggressive but this isn't a production run so time wasn't a big concern. Thanks for the help, I really do appreciate it.
 
A face mill would smear because the inserts almost always have an edge prep that makes them unsuitable for Ti. Also, 3" may be too large for a Haas, as it lacks stiffness. Stick with endmills for now.

Curiously, what are the thoughts on using a 1"-2" Korloy ripper mill for facing Ti? I haven't had to do any facing on plates to try it. I think with how free cutting they are that it may work well, aside from maybe frequent insert swaps.

Edit: I just looked up the cutter and they do have inserts for titanium. Has anyone given it a shot?
 
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Curiously, what are the thoughts on using a 1"-2" Korloy ripper mill for facing Ti? I haven't had to do any facing on plates to try it. I think with how free cutting they are that it may work well, aside from maybe frequent insert swaps.

Edit: I just looked up the cutter and they do have inserts for titanium. Has anyone given it a shot?

A smaller cutter with Ti-specific inserts may work fine, but I've just used mine on Al and steels (different inserts, of course). Do you have a link for the Ti versions?
 
When I want a super good finish on a top face in Ti I'll use the exact same parameters and cutter as if I were dynamic milling at full depth, but with a minimum cleanup for depth. The MRR isn't great, but the finish is.
 








 
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