Turning titanium on a duality lathe?

[FuriousGeorge]

So I need a m8x0.35 threaded rod made out of titanium for an anodizing line, and I'm wondering if it would be possible to machine this on a duality lathe. I've done some very basic manual work with the lathe on a rod of 303 stainless, but I've never tried turning (or even milling) titanium before.

Would this even be possible to accomplish with such a wimpy machine? I don't have a proper lathe, and I'm afraid that I'd have to take such light cuts on such fine threads that the material would harden and break my threading insert after just a few passes.

I'm sure it could be done, but this question is, could it be done in a few days without too much aggravation? I simply don't have time to learn the ins and outs of cutting titanium right now, and if the trial and error involved is going to take too long I'd rather just have someone else do it for me or rule out the rod as a solution to my problem.

Anyone have experience with this?

Thanks,
FG

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[Wirecutter]

This may be of limited help, but...

A couple of weeks ago, I was wondering the same thing. I picked up a "drop" of 1 inch round titanium bar and tried it out on my South Bend 9 (manual) lathe. What I have always heard about titanium is that you need hard and sharp tooling, and coolant is advised. Preferably flood coolant. Of course, I don't use flood cooling on the SB9, so I go slower. I used a brand new carbide insert. I ran the lathe at about 300 rpm and took light cuts doing both turning and facing.

I've used the SB9, the manual Bridgeport, and the Tormach 1100 on a fair bit of 304 stainless over the years. Compared to the 304, the titanium is wonderful.

Unlike 304, it doesn't seem to work harden. This meant that I could take light cuts and not worry that I wasn't "cutting under the work-hardened layer". (If I attempt a light cut on 304 and the tool is any less than scary-sharp carbide or stellite, the surface finish looks like the metal was being torn away, rather than cut. It looks and feels just nasty.)

Like 304, you want to keep it cool and use a sharp tool. Also like 304, if you get long continuous chips, they're murderously sharp. The surface finish is also pretty nice.

Note that I'm comparing titanium to 304, not 303. I did some 303 recently, and it caused me to slap myself in the forehead. If you're somewhat used to 304, as I have been, 303 is wonderful. I don't have a lot of time on 303, but in my limited experience, machining it is not very different from titanium. Titanium is just more expensive, hence, so are mistakes.

My $.02

-Mark

[FuriousGeorge]

Thanks for the reply, that gave me enough confidence to at least try it out. I was going to run at a similar RPM (a bit higher since I'm working with 3/8" stock) with a feed of around 0.008 IPR. What depth of cut did you use that didn't give you work hardening? I'm afraid my lathe will stall out if I try anything more than 0.02", maybe less.

[Kingjamez]

How long of a thread do you need? If possible, it may be easier to threadmill your part rather than do it on the duality lathe.

What kind of Titanium are you cutting? Since its for anodizing, probably commercially pure. It's easy to cut. Just keep your feeds and speeds right and you'll have no problems.

If you are cutting an alloy, you need to be a little more careful, but it's very do-able. I cut 6AL-4V on my little X3 mill and it works great, it'd be much easier on something like a Tormach. I've found that a fogbuster really improves the cut quality and dramatically improves tool life. Again, keep your feeds and speeds right, and you won't have any problems.

I use AlTin or NACO coated tools and they work great and have long life.

When threading, Ti tends to "bounce back" so take a couple of spring passes to get the right final depth.

-Jim

[twocik]

Depending on the diameter and length, it's very possible to turn on a Tormach DL. I've turned a few Ti parts for an anodizing rack with no issues on a 9x20. Shoot Mike an email/call, I'm sure he can get what you need minus the headache.

Titanium Racks in Chicago - Servi Sure

[BAMCNC.COM]

Anyway you can use Ti Tig Rod instead? It's what I use.

[Wirecutter]

Thanks for the reply, that gave me enough confidence to at least try it out. I was going to run at a similar RPM (a bit higher since I'm working with 3/8" stock) with a feed of around 0.008 IPR. What depth of cut did you use that didn't give you work hardening? I'm afraid my lathe will stall out if I try anything more than 0.02", maybe less.

My DOC was .02" or less. I was experimenting, after all. My SB9 is leather belt-driven, so I never really cut very aggressively anyway. I'm pretty sure the alloy is 6AL, but I don't have that info in front of me at the moment.

If you're asking about the 304, I generally don't cut any deeper than .02" with that, either.

-Mark

[jttoner]

This might not help, but when I worked at Douglas A/C (RIP), I sometimes had to drill Ti. I have no idea what alloy it was, but our method was to use cobalt tipped drills rather than the HSS we used for 6061, low speed and heavy pressure. It wasn't much fun, but it worked. What might apply to your project would be the hard tool and relatively low speed.

John

[FuriousGeorge]

Ended up cutting the Titanium today and it couldn't have gone better. I turned it at 900 RPM, 7 IPM and 0.02" DOC. I probably could have gone up to a 0.03" DOC, but I didn't have much material to remove so I didn't bother risking it. The M8x0.35 thread worked out nicely and I was actually able to hole a better tolerance in the Ti than the aluminum rod I used to test my G-code. Thanks for all the helpful replies!