Help with drilling Ti in a lathe

I just toasted a 29/64, 135 degree HSS screw machine drill. I'm drilling Titanium 6AL-V. My lathe uses oil, no water soluble. I was running at 675 rpm and .008 feed on a 29/64 drill. The drill made it about .250 and started glowing. Any suggestions? Obviously I need to go slower.
Thanks,
Carl

Try, say... 120-150rpm to start, might be able to go up a bit depending on how well its cutting and what oil makes it in there. Ease up on the feed a bit too.
Otherwise you'll need carbide if you want to go much faster.

SND said:

Try, say... 120-150rpm to start, might be able to go up a bit depending on how well its cutting and what oil makes it in there. Ease up on the feed a bit too.
Otherwise you'll need carbide if you want to go much faster.

Click to expand...

I'd get a Cobalt Parabolic drill instead of a plain jane HSS. 335 rpm .004 ipr. Its not aluminum lol.

I'm in a ornery mood, and I'm stuck at the shop cuz the roads are closed, so I'm going to bitch, constructively.

29/64, .450ish. 675 RPM's. Thats about 80sfm.

The bitching part. I had to calculate that. Why did I have to calculate that? Hmmm Cheenist? Its because you didn't. And you want to know why you are roasting a drill? Its because you didn't calculate it.

Just a pet peeve.

I'm not a Ti expert, but I did a shit load of it a month or so ago. I'd say its easier than 304. I'd say you need to knock down the SFM. 30 on the conservative side, maybe to 50ish.

Was this a chisel point? I wouldn't do that, if you have to, pilot with a 3/16 or so.

Feed seems heavy. Ti seems like it takes a lot of force to cut. I was running U drills, and then reaming with a .380 reamer, 2" deep, I was running conservative, really conservative while keeping a respective feed. and the drill was walking all over the place(split point cobalts). Went to a bit smaller drill, straighten with a 3/8 endmill, and then ream. Hole size was a mess. The damn reamer was bending. Chopped the reamer down, and everything was fine.

Back it down, get some good drills and you should be fine. The 6Al4V really does cut easy. Just don't beat on it.

Bob, chill out! It's only snow, and besides, it is Christmas.
If anything, I have somethin' to bitch at cus' you guys down'nere almost at the equator havin' all kinds of the white stuff and we ain't got nuttin' but damm rain!

About the SFM in TI, you're right about 30FPM, with HSS might even be 20.
I do disagree on the split point tough, I've always found them to be superior.
For feed, .003-.004 is also OK.

Now, a trick I use for drilling TI: Spin down the flutes a little to about -.01 under nominal, starting approximately 1/4" back from the tip.
TI likes to close in on the drill, which increases heat by some insane amounts.
By spinning it down, the unused portion of the flutes will not rub.

Bob,
I'm in an ornery mood too...just toasted my only drill. Parts are due Tuesday, my new drills won't be here 'till Tuesday. I actually did calculate it....just didnt include it in my post, sorry. Heck, aluminum is what I run mostly, but I did do a Ti job way back when. I chose 80sfm because that's what my carbide inserts are running at....I know the drill wasn't carbide...that's what my almost 60yo mind said the nano second the drill started glowing....tooo late. The drill WAS a split point...now It kinda looks like Superman.(has permenently welded wings on it).
Carl

Cutting speed for high speed vs carbide is like 3 or 4 times less.. Maybe a small pilot drill would help you too

I have not machined any production Titanium. A former employer had though and told me some of his methods. He never enlarged an already drilled hole with another drill or reamer. He considered it suicidal. I saw some of his drills that he used on titanium. As Seymore mentioned wide lands on the drills were a problem, so he had used a bench grinder to thin them down. He ground from the trailing edge and thinned the land till it was just a few thousands wide, much like the apearance of an end mill. On his screw machines he have used cutting oil, but I have heard coolants can work well also.