cutting titanium with plasma torch

I have a request from a client to cut some titanium sheet with a plasma
torch. The torch I have uses air and I'm a little concerned by the MSDS
on titanium where it says that the dust is quite flammable and the the
metal will ignite in air at 1200 degrees centrigrade. Anybody have any
experiance doing this sort of thing? Any comments on the safety issues?
What is the likelihood that I will set the sheet of titanium on fire
with the torch.
Reply to
Steve Schlaifer
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--Been there, done that; never had a problem with a spontaneous fire, but the process does generate gobs of smoke, so do it in a well ventilated area. Leaves a gawdawful burr on the backside and you'll have to grind that off, too.
Reply to
steamer
Steve Schlaifer fired this volley in news: snipped-for-privacy@hawthorne.kihakkt.jetcafe.org:
The likelihood is rather large, and titanium burns readily in atmospheric oxygen, once ignited.
You need inert gas for this, and it wouldn't hurt to do the cutting in a "tent" flooded with gas above and below the cutting area.
LLoyd
Reply to
Lloyd E. Sponenburgh
Yes, don't do it. Would you cut magnesium with a plasma? Ti is nearly as flammable, once you get it hot. The dust would be oxidized, and not too bad, but once the side of the cut gets hot enough, WATCH OUT! This might only take seconds after the punch through before the whole plate lit off. Once ignited, it would be extremely hard to put out, with white-hot tracers flying around. Putting water on it will cause a huge "explosion" of molten metal, the only thing that is likely to work is embedding the whole mess in sand dampened with fire retardant foam.
If you have any doubts about the specific alloy, ask for a SMALL piece and try it over a bucket of sand. If it explodes, you have your answer. If it doesn't, that doesn't prove it is safe, just that that particular alloy less flammable.
And, maybe I'm off base, I just know that you need extreme precaustions when doing any welding on Ti. Generally you use extra shielding gas on the back side of the weld, and accidents still happen.
Jon
Reply to
Jon Elson
The pigment generally used for white in paint is TiO2, which would be the product generated during the cut. I bet the smoke was white, and depending on particle size, very thick. Hopefully, the thermal conductivity of titanium would be high enough to cool the haz below the temperature needed for combustion under most conditions, but who knows? Sounds nasty.
Pete Keillor
Reply to
Pete Keillor
I might also be way off base here, but I think that the reason for all the precautions with Ti is to ensure a good quality weld, not to specifically prevent a fire. Ti oxidizes readily, and the oxides aren't very strong, hence the need for a well shielded welding zone. I've never heard of any metal fires starting in the bulk material, only in the swarf. Keep in mind that one of the attractive features of titanium is it's high heat strength, hence it's use inside of jet turbines, a horrendously hot environment. Of course YMMV. This is probably a good question to ask over in sci.engr.joining.welding.
Pete
Reply to
Pete Snell
Check out and look at the 'recommended processes' near the bottom. Ti and Mg are listed as ok.
Also check out lots of good info there.
One thing to be careful of, not just in the case of Ti, is mixing of swarf of different metals, which can cause a a much bigger reaction than that of a single metal. (think thermite)
Pete
Reply to
Pete Snell
You can cut Ti just fine with a plasma cutter. It does produce an amazing amount of white light. Can be rather startling the first time. You will have a burr on the metal after the cut, and a heavily oxidized edge that would need to be ground before any welding.
Reply to
Ernie Leimkuhler

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