Titanium cutting confusion

[L1A1Rocker]

I'm still gearing up to turn some titanium but I'm confused and frustrated right now. I've got my material and my form 1s back and upgraded to an AXA Quick change tool post BUT! I'm not sure what tooling to use.

I have some insert sets that accept the triangle shaped inserts but talk about confusing. Not only do I not know what kind of material to get for them there is also size, and several angles to consider. (If it makes a difference I have insert holders that have a square shank measuring 1/2 inch and 3/8th inch. - the 1/2 inchers are really nice) But I'm really used to working with 1/4 inch tool bits that go into the old style tool holders on a lantern type tool post.

Considering my experience I was originally looking at purchasing some 3/8ths or 1/2 inch HSS tool bits to go with the new quick change tool holders. But, I've read too much on turning titanium that I've gone in a circle and confused myself. Is straight HSS best? I've read that it is when you run it really, really sharp. Should that be 60* point sharp, or a 90* profile to the work sharp? I've also read that HSS with carbide or cobalt added to it is best for turning titanium. But even then there are different amounts of this like 5%, 8%, and 10%. So again, what do I really want here for Titanium?

The only thing I've really come down concrete on is; 1) run a misting coolant system, 2) Keep the RPM down low, and 3) use a fast feed rate.

So can someone with Titanium experience please spoon feed me a bit of information?

First: If using HSS tool bits what exact HSS should I use? Should it have a bit of cobalt or some such in it? If so, what percentage?

Second: What shape should I grind the HSS bits to?

Third: If using inserts what Alphabet soup code should I use to order the right triangle shaped inserts for the 3/8ths size and the 1/2 inch sized bit holders?


Thank you folks very much for any input you have.

[kingjamez]

I think you are over thinking this. Go put some Ti in your lathe and try things until you find what works best on your machine. You are right, keep the surface speed slow and the feed rate not slow (I would't say fast). Sharpen your bits like you always do and see if they work.

-Jim

[john.t.little1]

I recently got into machining Ti and people told me I coated and sharp inserts is what works. I've used TiN coated inserts and they work just don't leave as good of finish. I've also used solid carbide boring bars they work great too just don't get worked up over it hell when I was in Iraq learning how to use a lathe I made a Ti ring with hss tooling and a file. Just take your time and learn with what you have

[Bendersquint]

The only thing I've really come down concrete on is; 1) run a misting coolant system, 2) Keep the RPM down low, and 3) use a fast feed rate.

So can someone with Titanium experience please spoon feed me a bit of information?

First: If using HSS tool bits what exact HSS should I use? Should it have a bit of cobalt or some such in it? If so, what percentage?

Second: What shape should I grind the HSS bits to?

Third: If using inserts what Alphabet soup code should I use to order the right triangle shaped inserts for the 3/8ths size and the 1/2 inch sized bit holders?

I have never turned titanium using an AXA, I used BXA to start and now in a CXA and CA tool holders. You need rigidity to get consistent results.

1 - I use indexable inserts, the inserts I use for my main turning are VNMG 432's designed for exotic alloys. They run about $75 per insert. They last forever though but for a Form1 project may not be worth the investment. The titanium is turned unbelievably easy.

2 - The shape will 100% depend on the shape of the tool and the grade of Ti you are turning. I am assuming G5 and NOT G2?

3 - I can't help you on the triangle tools as I use VNMG, WNMG and CNMG inserts for all my profiling.

You have to run Ti RPM slow, feed higher. This is why rigidity is key!

I work Ti every day and never have any issues.

[57fairlane]

I think you are over thinking this. Go put some Ti in your lathe and try things until you find what works best on your machine. You are right, keep the surface speed slow and the feed rate not slow (I would't say fast). Sharpen your bits like you always do and see if they work.

-Jim

I would go with this.

Honestly, I just run 90-100sfm and turn O.D./I.D.s at .006-.007/rev for finishing. Nothing fancy. I've got flood coolant though

[Dr.K]

Sacrifice a small piece, and practice!

That is exactly what I did.

And the best advice I ever got was from bender, I believe it went something like

set up needs to be ridgid, ridgid, ridgid!

[Fulmen]

My experience is that Ti cuts fairly well with sharp, positive carbide, I suspect the ones I used were for stainless or general purpose fine cuts. I can't remember what worked best, I believe it was medium cut, somewhat heavy feed (please correct if this isn't right). Anyways, I suspect you get the feel for it yourself. It's springy (low youngs modulus), a very poor conductor of heat and work hardens badly, perhaps something aluminum and stainless.

Springy means deflection, so keep the cutting forces to a minimum. Sharp tools helps, it should also reduce work hardening. Due to this you need to cut deeper than that layer (perhaps 0.1mm) to reach softer material. And since it conducts heat poorly you need lots of coolants and moderate speeds. I don't know what cooling methods are best, but unless you plan on doing this on a daily basis (in that case you should talk to a professional machinist) there isn't any need to buy new equipment. Flood cooling works just fine.

And do be prepared for looooong stringy turnings, sharp as h*ll.

[CMV]

Anything that works well on stainless has worked well on Ti for me.

If you're talking about these or very similar triangle inserts I've found little to no use for them. A set like this came with my lathe & they don't turn anything well.



I don't know how well mist coolant will work out for you. Never tried it, but your tool will get white hot almost instantly. It generates a crazy amount of heat. You'll go thru inserts quickly without a good coolant setup. Mist might be perfectly fine - don't know since I don't have it. If your machine can handle flood coolant, I made a real cheap system with a 5 gal bucket & a HF fountain pump. I might have $30 of materials in it. Not nearly as nice as a real system, but it works. Adding $12 worth of loc-line would be a considerable upgrade. I can provide details if you're interested, but it's not a difficult thing to just figure out & make in a few hrs.

[kingjamez]

It's springy (low youngs modulus), a very poor conductor of heat and work hardens badly.
And do be prepared for looooong stringy turnings, sharp as h*ll.

I've heard that, but the only time I worked hardened Ti was when I had a programming error and the tool plunged straight into the workpiece. It burned up and the carbide began glowing. The Ti did work harden there, but I broke through it with a carbide tool and a very fast feed.

My swarf is also very soft, almost like ribbon, not sharp at all. 304 on the other hand, cuts my hands to shreds.

-Jim

[kingjamez]

I don't know how well mist coolant will work out for you. Never tried it, but your tool will get white hot almost instantly. It generates a crazy amount of heat.

I did quite a bit of cutting in 6AL-4V with no coolant at all and got what I thought was decent tool life. I used a slow surface speed, the right speeds and feeds goes a long way. I eventually added a fogbuster style system and found that tool life was further extended and that the finish slightly improved.

-Jim

[Bendersquint]

Never tried it, but your tool will get white hot almost instantly. It generates a crazy amount of heat. You'll go thru inserts quickly without a good coolant setup.

You are doing something wrong if its getting that hot!

[paul463]

I think you are over thinking this. Go put some Ti in your lathe and try things until you find what works best on your machine. You are right, keep the surface speed slow and the feed rate not slow (I would't say fast). Sharpen your bits like you always do and see if they work.

-Jim

This the way I went. I hand honed my HHS cutters as sharp as I could get them after grinding and they worked just fine, and I used no coolant at all..

[57fairlane]

It's springy (low youngs modulus), a very poor conductor of heat and work hardens badly.
And do be prepared for looooong stringy turnings, sharp as h*ll.

My swarf is also very soft, almost like ribbon, not sharp at all. 304 on the other hand, cuts my hands to shreds.

-Jim

Me as well . . . with grade 5 and 9.

The burrs can be sharp (what burr isn't?) primarily at the lead-in of a thread and almost always leaves a little something at the lead-out in a tube where the minor is the inside diameter of the tube. Otherwise my strands feel like packing material, a little spongy.

304 is terrible, 316 is the worst. I've cut myself 4-5 times pulling 316 strands. I've gotten smart enough that I don't touch it with anything other than welding gloves pulling it out of the chip pan or pliers/channel locks if I need to grab it from around the part.

[Baffled]

For lighter home machines which is 95% of us here, I swear by HSS ground with aggressive rakes and with a fairly small tip radius. Feed very slow. Carbide shines in material removal / time, which is how a commercial shop makes money. Since we have plenty of time, we can maintain a lot of control in the cut by using HSS.

I don't use flood, I simply slobber on an appropriate cutting fluid, keep it nice and wet.

[Fulmen]

the only time I worked hardened Ti

You've might have done it during normal operations as well, it's not like the only options are soft or hard as glass. I suspect it's hard to avoid any work hardening, but if the layer isn't too hard or thick it won't cause too much problems. Using the right DOC/feed and proper inserts should also help reduce the problems.

My swarf is also very soft, almost like ribbon

Guess you know what the heck you are doing

My main problem was the Chinese lathe. It's accurate enough, and behaves fine as long as you don't get too greedy. But it isn't really stable enough for heavy cuts, so that and my patience limits my options. All in all I had few problems turning Ti, with the exception of parting. It simply wouldn't cut with the standard inserts I had available.

[jds1975]

I've been practicing with Ti for the last 8 months and am finally making my 308 can as we speak. HSS works fine. As for AXA holders, I am having no problem on my small shop lathe. I am using super alloy inserts. I get mine from shars . The inserts I'm using are YD101. They are for semi finishing of cast and non-ferrous alloys. And semi-finish to finishing of Ti. The actual insert I'm using from shars is CCGX 21.51 YD101 . And they are less than $6 each. I run at mid to low rpms and take light cuts with consistent feeds. Am only using coolant to drill. Very low rpms and lots of coolant when drilling. Hope this helps and good luck.

[Fulmen]

Inserts for super alloys or finishing stainless seems to be the favored choice, as theory would suggest. Sharp HSS should work fine as well, it is well known for allowing low cutting forces and good surface finish in a wide range of materials. If you are going to machine Ti on a regular basis I suspect there is much to be gained from investing in proper tooling, but for us amateurs it's not necessary. You take what you have and make the best of it, seems like most manage to work out the kinks pretty fast. Don't know about the OP, but I've learned a lot from you guys. And considering the possibilities titanium provides (not least the beautiful colors it can be anodized to) I am sure I'm going to use it more in the future.