View Full Version : Machining titanium on a lathe
I'm new to this group, and it looks great!
I have a couple of questions for the (very) knowledgable machinists on this forum...
I have acquired a 1" rod of aircraft titanium (from Boeing Surplus?), and I would like to know of any hints for cutting it on the lathe. I thought I'd just make a plain ring (finger ring) for starters to feel out how it cuts and finishes. I've read that it is as difficult to machine as 316 stainless...which doesn't like to be machined at all! I have a South Bend 10-Heavy lathe.
1. Any pointers on lathe cutting techniques for titanium?
2. Any pointers on getting a bright finish? Titanium finishes I've seen all seem to be dull...or brilliantly colored...
NW Computer Engineering
06-28-2002, 09:51 PM
Titainium is naturally a dark grey material. Bright finishes are from PVD coatings or plating. How well it can be plated - I do not know.
You need to use T-15 HSS bits or Inserts to machine it best. It does machine similar to 316 as far as SFPM goes, maybe a touch slower. If you have trouble machining 316 I do not think you are going to be able to do Titanium very well either. Some of the alloys are a bitch to machine - do you have an alloy number for it? It should be marked on the side of the bar.
Based on my limited experience with titanium, it turns pretty well. At least the alloy I had did (no idea what it was). Wicked sharp tool, not too fast. Cutting it generates a LOT of heat, and titanium is a poor heat conductor, so things get hot fast. You'll probably want to use coolant of some kind.
06-29-2002, 06:36 AM
You will definately want to use coolant when cutting titanium, it will ignite and burn if temps are high enough, these temps are not difficult to reach when turning. without the proper chemical you will not be able to extinguish the fire. DO NOT USE WATER AS A STEAM EXPLOSION WILL RESULT, IT WILL HAVE NO EFFECT ON THE FIRE.
I use titanium quite often and by keeping it cool there is no danger. And it can be polished to a bright finish.
Many thanks for the input!
In the past I have successfully machined a few good 3/8" bolts from 316 stainless, but in my first efforts it felt like I was machining rubber stock with rubber bits! I soon learned that razor sharp carbide bits and slow speeds worked fine as long as I didn't hurry. But that was a long time ago...
The temperature thing worries me. I didn't know titanium would burn in air at fairly low temps! I know magnesium can be very dangerous to machine in the home shop...the chips are extremely flammable even at room temperature. I've stayed away from any machining of magnesium for that reason.
Any tips on a coolant? I usually machine just brass and aluminum...quite small parts (for optics)...and I've only dry-machined for a long time now. In fact, the only fluid I ever use these days is for tapping...using an ancient can of TapMagic.
06-29-2002, 11:00 AM
One of the attributes of titanium is its temperature resistance, 2000*F, I don't think flammability is problem as it is with magnesium.
For a small HSM lathe (Atlas, Southbend bench lathes, etc.) HSS is best to use. They cannot handle forces needed for carbide. A good sharp cutter, low speeds and coolant will work wonders.
A good water soluble coolant, or sulfur cutting oil will be as good as anything. TapMagic is good for tapping, but pricey for lathework. Get a general purpose water soluble coolant, and apply with a pump spray bottle. A gallon will last for years. For aluminum, I still think WD 40 is best.
06-29-2002, 01:02 PM
Fire is definately a hazard. Tried to set the lathe on fire turning the stuff, saw this glow under they ways grabbed the chip rake and dumped the glowing stuff on the concrete floor and covered with sand. Other than that it cuts well.
Although I have not tried it, I have heard that you can put it in dry ice before machining it to improve machinability.
07-02-2002, 09:50 PM
Some grades of Titanium cut like butter--PROVIDED YOU KEEP THE RPM DOWN. I frequently make custom rings for jeweller friend. Beautiful formed finishes are easy.
Reactive Metals Studio, Inc. (firstname.lastname@example.org) sells a 1"dia. X 12" long billet of jewelry grade titanium. Approximately $40.00.
Look up titanium rings on internet.
07-02-2002, 11:33 PM
That must be just commercially pure Ti - no alloy. Cheaper than the rings I have seen! http://bbs.homeshopmachinist.net//rolleyes.gif
07-03-2002, 08:46 PM
Correct. Catalog describes it as Commercially
Pure Grade #1 Titanium.
Ring mfgs on internet offer their rings in two grades. One is harder and more wear resistant, an alloy of 6% Aluminum,4% Vanadium, 90% Titanium.
I have only cut the No. 1 grade. I make my tools out of 3/8" X 1/4" guage stock and harden and draw them with a torch. I use endmills to form the needed radius form using steep cutting angles (just angle the piece in the vise as you are cutting the radius) and I keep them razor sharp. If slow rpms are maintained the titanium seems to cause minimal wear. Makes the prettiest chips I have ever seen.
07-03-2002, 09:00 PM
If you are serious about making rings then you should purchase Gesswein's Platinum Buffing Compound Sample Set. www.gesswein.com (http://www.gesswein.com)
Also will need 4-4"dia. muslim buffs and a Satin Finish Buff.
Better yet make friends with a jeweller. All jewellers need a machinist friend.
07-04-2002, 04:14 AM
Do you recommend Shiite or Sunni buffs?
07-04-2002, 11:55 AM
Oops! musliN not musliM. Had me guessing for while Unc. Now you've got me laughing. Must have been that SECOND glass of Merlot.
07-11-2002, 09:32 PM
If you want to put nice colors on the titanium ring? Put it on a wire loop and hold it over burning gasoline. If you do too much, buff it out and start again. Don't tell any one, I gave out that trick-SSSHHHH!
Ti is flamable. I do not use coolant on it when spinning it on the lathe. I tried it the 1st time and set fire to my lathe. Ti produces its own oxagen when burning. so dont try water on it or a normal shop extingusher. I brole it into small piles and let ity burn out.
Just my .02 worth
07-26-2002, 04:12 PM
I did not know that Ti was a fire hazard.
So far I have only cut some Ti bar with a hacksaw to make TIG fill rod, have not turned it in a lathe.
It welded OK, anyone know why TIG did not set the Ti fill & Ti casting on fire?
07-28-2002, 01:39 AM
Titanium in not a pyrophoric metal - unlike Magnesium, Uranium, Zirconium, Niobium, and Indium. I have never seen it set on fire, smoke, or smolder. Seen all those others do that...
If it was every SR-71 would burn up from the extreme heat of mach 3.4+ travel in air. It is tough to machine alloys like Ti(13V-11Cr-3Al) (260,000 psi tensile, .3x machinablilty compared to 200 Brinell free machining steel) as the heat can readily ruin the inserts - coolant is a must with this stuff.
Zirconium is just as difficult to machine as Titanium, it looks similar and DOES burn. It is used in nuclear reactors to accelerate neutron flow and Hafnium is used to control it - Zirconium and Hafnium occur together in nature too. It is quite possible that what you have been machining is Zirconium - they are quite similar in properties and appearance. It is a controlled substance and illegal to own - ask your local University to test it for radiation and on a mass spectrometer.
[This message has been edited by Thrud (edited 07-28-2002).]
07-29-2002, 03:58 PM
check out titanium industries web site, they
have a machining guide
07-29-2002, 05:07 PM
This is an interesting website. Stresses titanium's fire resistance as one of it's major attributes. Wonder how those guys managed to have it catch fire on them?
07-29-2002, 07:00 PM
Only thing I can think of is they are machining Zirconium - it will burn in the air if heated and looks and feels similar to Titanium. I was trying to figure out what was going on and that was the only thing I could come up with.
07-29-2002, 07:35 PM
Ti chips can burn. Been there, done that. http://www.titanium.com/tech_manual/tech15.cfm
p.s. Ti has an oxide coating like Al and when cut this layer is missing and reforms on the hot chip in a vogerous manner called fire.
[This message has been edited by NAMPeters (edited 07-29-2002).]
07-31-2002, 02:23 AM
Thanks for the url - most informative. I was unaware of the 480* ignition problem with <100 mesh dust. I did not know paint dust would do that either until it set our dumpster on fire. I have seen the other metals I mentioned burn (along with Na, Li, & K in water) but have never seen a Ti chip burn. I stand corrected again - geez I am a dork. Twice in one day. I will have to try burning some now! http://bbs.homeshopmachinist.net//biggrin.gif
07-31-2002, 01:57 PM
Any one dealing with metals dust should go to fire code and readup. Ground small enough, most will burn and even explode. Flour dust, brain dust cotton lint (as in clothes dryer) oxidize with ease and speed.
Lee Valley catalog had a story (I think it was Lee- comments please) about a grinding wheel use for iron and aluminum that exploded. I've doubts about the story but it is possible given right conditions- I guess http://bbs.homeshopmachinist.net//smile.gif
07-31-2002, 07:30 PM
What is brain dust?
07-31-2002, 08:30 PM
brain dust = dandruff
07-31-2002, 09:18 PM
It is doubtful you could get a high enough concentration of brain dust to explode. Brains will autoignite. Dumb salesclerks frequently seem effective with mine.
As regards the rest of post, the link on Titanium was interesting. I have been trying to find similar information for other materials, such as iron, as I suspect information will be quite similar. Many MSDS's I found for Titanium listed autoignition and explosive limits as N/A. Iron too.
Iron is very easy to get to burn, you can light steel wool with a match. It is not easy to extinguish either.
The mention of dust explosions was generic, and should not be taken lightly, dust plus ignition source can be very hazardous.
07-31-2002, 11:32 PM
Zirconium was used in cluster bombs ond other high explosive applications.
After Steve's warning about brain dust I will put the q-tips I use in my ears in the fire proof rag can and not the garbage. If I run a towel straight through both ears does this work better than the q-tips? I have seen Stimpy do this, but he removes his brain first with tweezers ("It's so small...!"). And should I use coolant in this procedure? http://bbs.homeshopmachinist.net//biggrin.gif
08-01-2002, 08:48 PM
Re: Brain dust.
Gents please be informed that ALL my posts should go through Microsoft spell check, etc.
Microsoft agrees that "brain dust" is a OK phrase- when I use it. Microsoft also approves of "grain dust"- which explodes also, Drain dust which is rare,Krain dust is a protected specis, Train dust is now rare.
Hope you are more aware than before http://bbs.homeshopmachinist.net//smile.gif
08-01-2002, 10:10 PM
Don't blame macroslop for your airrors - you no bill gaates nevur makes missteaks. I uze thair spel cheecker awl thu tyme and I doant git mistaks! Four sham, Steave... http://bbs.homeshopmachinist.net//biggrin.gif
Brain Dust: n. - what you get when you put your nose to the grindstone too long without the right coolant, also that funny smell in your mouth when the dentist says "oops! nurse call this number - quick"
08-02-2002, 01:10 PM
read it again, bud- I said "should" not "did or do". I bet I read my "Brain Dust" post after I posted it and every time I read it it said "Grain Dust". Since it went up right at 2 Pm and was wrong by 8:30 when Composite found it, it must be Neil's fault. To Whom and where do I lodge a complaint? http://bbs.homeshopmachinist.net//smile.gif
Peace, Gents http://bbs.homeshopmachinist.net//wink.gif
08-02-2002, 07:10 PM
Relax - it was a hoot! I read grain dust too (brain thinking instead of reading) - so don't feel bad. Those test to see who's paying attention - you had it all planned, you sneaky bugger! http://bbs.homeshopmachinist.net//biggrin.gif
08-02-2002, 08:04 PM
Dave- no problem, I thought it was funny also http://bbs.homeshopmachinist.net//smile.gif. I have NO use for a person who can spell a word only one way (courtesy Mark Twain), I seldom make so fitting a mistake.
May you all find many more as good & point them out. http://bbs.homeshopmachinist.net//smile.gif
08-02-2002, 10:54 PM
You sound like a Wah Chang engineer.....
08-04-2002, 04:55 AM
What in heck are you talking about? I need more input (like #5), more Input!
Remember, I am Canadian - I do not listen to Rush Windbag! http://bbs.homeshopmachinist.net//biggrin.gif