Titanium

"best wire" wrote in news:1176444209.341770.37560 @y80g2000hsf.googlegroups.com:

Have a good, fully charged, dry chem fire extiguisher handy (or two).

You must be thinking of magnesium.

Titanium is not pyrophoric.

You have to use a very sharp tool bit, as it will gall easily!

Treat it much the same as Stainless. Use fairly slow cutting speeds and fairly heavy feed. The main problem with titanium is that it work hardens so easily. If that happens it will harden to the point that it will be nearly impossible to cut it with high speed tooling.

I have certainly machined titanium H.S. tooling but if you have machinery that can use carbide tooling it will probably make life a bit easier.

Bruce in Bangkok (brucepaigeatgmaildotcom)

Titanium is a little hard to light, but once burning, it's ferocious.

If you're spinning off chips at the "smokin' blue" stage, you'll likely have a titanium fire. Flood coolant is the only safe way to turn the stuff.

LLoyd

Titanium flake smaller than 400-mesh IS DOT listed as pyrophoric. It (legally) must be transported under water in commerce.

Normally, machining operations would produce particles larger than that (400-mesh is roughly 1-1/2 thou.), but you could get down to that size pulling swarf on a last finishing pass.

Again -- flood coolant is your friend.

LLoyd

I have done work for a local company that manufactures titanium, and they have had cnc equipment heavily damaged by fire. Yes, indeed, ti chips are flammable.

It also pays to change inserts before you think it's necessary. My experience machining the stuff lead to a few broken inserts that failed and broke, destroying the insert. It's not fun material to machine. Real nasty to tap.

Harold

No kidding it's nasty to tap. If you use a tap that's been used on steel, tapping Ti is a real pain. I finally started buying taps just for titanium---they live in a special box marked FOR TITANIUM ONLY. Makes things so much nicer. I only use 3 sizes on Ti,

Bill

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What about using ceramic?

I get to make titanium bushings on occasion.

Not too fast on the rpm, flood coolant, and a deadly sharp high speed steel tool with a bit of positive rake. Works for me. A scary sharp tool allows a light finish cut if required for looks.

I have used carbides for hogging a bit, but was not really happy doing so.

If the drill squeaks, it's already too late!

The stuff I work normally work hardens like a SOB if the tool rubs or is a bit dull. 6al4v mainly. Mostly I deal with rod under 3/4 inch, so my strategy may not be suitable for your purposes.

Cheers Trevor Jones

What Trevor said. Sharp tools with positive rake. Make sure feed per revolution is high enough and depth of cut is deep enough to get under the work hardened surface from the previous pass. When milling use high spiral endmills. These cutters will not only cut better they will deflect less and last much longer. ERS

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Not a sharp enough edge.

I believe what you are refering to is Titanium Trichloride which is is pyrophoric, and is DOT classified as a HAZMAT. Under most circumstances pure Titanium metal will only spontainiously combust when its temperature reaches approximately 600ºC or higher. But Titanium has an affinity to oxidize, so it may reach combustion temperature if it oxidized rapidly enough, but Titanium powder can be transported dry, according to DOT HAZMAT Regs.

There are no cautions of fire hazard from machining Titanium in Machenery's Handbook. I guess that you could probably start a fire if you were machining titanium dry, but who would want to do that? Then again you can start a fire machining steel or aluminum.

I agree that ceramic isn't sharp enough, and I am not sure that I would even use carbide. Carbide would probably get-er-done, but HSS is sharper, you just have to change the cutting tool more often

It will certainly ignite chips and swarf simply from machining.

"best wire" wrote in news:1176444209.341770.37560 @y80g2000hsf.googlegroups.com:

Seeing as you don't say what type of titanium nor what kind of lathe, I'll stay on the conservative side.

HSS tool - Grind 5 degrees of side rake, end relief and side relief. 0 back rake. Take .040" depth of cuts at 180 RPM and between .001-.005 IPR feed rate. Use flood coolant. Keep the chips from piling up and you might not have a fire. Don't listen to the folks who say it's not pyrophoric, they are dead wrong.

Carbide tool - Run 450 rpm same feed rates as above. But use 7 degrees of side rake, end relief, and side relief. Again no back rake.

Make sure you have some tool nose radius. Anything from .008"-.032" should do. Don't feed too fast and don't let it get too hot.

These speeds are safe for age hardened Alpha-Beta alloys. You could easily double them for CP titanium. If you don't know what you have, then stay slow.

Watch this video:

About 2-1/2 minutes into the video these morons cut some titanium dry. They are lucky it didn't get out of hand. I've seen more than one CNC lathe or mill burned to the ground from Titanium fires.

The machine is a cheesy Chinese POS CNC Swiss type lathe with a noisy spindle and a whole lot of chatter.

Thanks for the good info.

I havn't done a lot of it but I found that very sharp ground edge carbide inserts work best, and you can tell when they get dull, which will happen quickly once it goes. I was using Kennametal CNMP 432 KC730 insets, these are high positive ground edge TiN coated.