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Titanium Drilling help?


Cast Iron
Jun 17, 2013
Bonners Ferry
Hi guys!

I never machine Ti.

But nevertheless, I find myself needing to make a couple cores with 13/32 thru holes. Material is 1-1/2" Ti-6AL-4V Going about 25X Deep! (about 8" long) Bought 2 Nachi parabolic HSS drills for the job. Running Qualichem 256 in a Hurco TM8 lathe.

Any conservative estimates for feeds and speeds I should use? Don't care how long they take, would rather not trash the drills and need good parts. Push hard, spin slow? Peck or no peck? Figured on starting the hole with a screw machine length cobalt drill to about 3/4" deep or so.

Thanks for the help!

198 RPM, 0.5 IPM. Start with a stub or screw-machine length drill, then go to a jobber, then go to your long ones. Cross fingers that the drill doesn't wear out before getting to the bottom of the first hole; the moment it starts acting / sounding different, pull it out and resharpen or replace it. Better yet, get coated carbide thru-coolant drills.
25 diameters sounds like Gun Drilling to me more so then Twist Drilling. Talk to some Gun Drill manufacturers. Although making only two I suppose a person could squeak by without.

I mean mhajicek is our resident Ti expert, but just another idea...
I have never done any production machining on titanium myself. I worked for a man that had multispindle screw machines. He told me some of his "secrets". One was thinning down the lands near the tip of the drill. The other one I remember is never try enlarging an existing hole with a drill (like going from 3/16 to #7). He ran cutting oil in those machines. One of the parts he made was the windshield spacers for Boeing 747 or maybe the DC -10, the spacers were about 2 inches ling with what seemed like a #10 through hole. It was a long time ago and I maybe off on the hole size.
my experience in aerospace is Ti & stainless speeds and feeds are pretty close together, at least starting point, coolant, coolant, coolant!
Carbide TSC drill is really your best bet. All the pecking and little coolant that HSS para drill is going to get is going to smoke that thing long before it gets to the bottom. Titanium needs a razor sharp edge and tons of coolant, otherwise the drill will rub and work harden the hole floor and blow the drill up on the next peck.
I'm new to posting but have been coming here for tip quit a while, so I'm not sure what I can say but in TI my go to drills are Iscar camdrill, partially because once we get the job its 100-300 pcs orders per 6-12 times a year but i might get 1000 holes per tip depending on size and depth and how aggressive.
Make sure you do break it up in into a few different operations, Spot -> Stub drill smaller size x3D -> Ream that hole to you drill size for a nice bushing -> then deep drill.
Exact SFM & IPM I cannot say, but try to ensure you peck at a rate of 3,2,1,.5D and the remaining amount at .5D make sure at the 3,2,1,.5D you have the drill come out of the hole to clear chips.
I run these parameters all the time in 304 to Hastelloy X.