Safety

Hi Circlip, (and anyone who wants to know more)

I do wonder why you mentioned on a model engineering forum the fire potential of Titanium and the risk involved with oiled Kraft paper, most model engineers will, most likely, have never seen or touched Titanium let alone machined it. Industrial machinists would have no need of protecting their mill tables in such a way, and they would or should know how to handle such "exotics"! If a large mass of Titanium does catch alight, through carelessness, the paper will be the least of their problems.The new listing of machining materials, will help to educate those wishing to use some of the more exotic materials.

For those unfamiliar with Titanium, it is a light weight non rusting metal, it is easy to machine PROVIDED you don't let the tool rub. If you think Stainless work hardens, it is as nothing to Titanium! Titanium will almost "spontaneously" combust, if provoked but read more further down. Quite a few non professional designers ask for it thinking it is the answer to all their weight and strength problems, WRONG. What they really need is a metal called "Unobtainium", but that is another topic.

Now for those interested in some personal experiences;-

In a Titanium fire, what happens is it smolders brightly, very pretty but if one does not let the shavings built up to any great extent it is only a minor inconvenience. Granted one must be aware of the risk, but Magnesium is in a whole different ball game. When Magnesium burns the temperature is so great that water, put on it to quench the fire, can be split into Hydrogen and Oxygen thus fuelling it, hence the use of sand in wartime fire drill. A few shavings of Titanium can virtually be spat on, that's if they don't just burn themselves out before you can think about it. Moral is, don't let them build up to a critical mass. Magnesium and Titanium are similar in that they both emit a brilliant white light when burning, but their rate and ease of combustion are somewhat different.  If you have had a serious Titanium fire, you must be remarkably clumsy or careless !

Titanium burns because it has a very bad ability to conduct heat, so the temperature is maintained once built up by friction until there is enough heat to cause combustion. Clearing shavings prevents this happening, as does sufficient coolant. To demonstrate the effect to "newbies" I often put a bundle of Titanium swarf on the ground and light it with a gas torch, as I said it smolders and then goes out, but it is fun to watch the smolder run along a filament, but is it dangerous in that situation, not at all. The metals lack of heat conduction seems to prevent the heat escaping, to the surrounding. It does teach the said newbie of the risks though. In my opinion, plain ordinary wire wool is far more dangerous; there just a spark from a grinder can set it off, something that will NOT happen with Titanium. Do you have wire wool in your workshop, well I hope you keep it in a tin, lest those pesky little sparks contrive to spoil your day! If you really want a fire risk, you could not do better than use a Linisher to remove rust and then grind some Aluminium, in case you don’t know, that makes a compound called Thermite, look up the risks involved with that!

This morning I did another firing of some Titanium shavings, a small bundle about the size of an egg. (I keep some handy especially for demonstrations)  I lit it with a gas torch, as per usual, and sure enough a very bright light, but it soon went out. I then lit it again, more bright light and then it went out again. I had to light it fifteen, times at different points, before it all oxidized. Now I am not saying you want this to happen by accident on your precious machinery, you don’t! Certainly a large mass of shavings or swarf, once alight, could really spoil your sunny disposition, so don’t let it happen. 

The astute amongst you will of course point out that the shavings were cold before the fire, so the rate of combustion was slower than if they were hot and fresh off the lathe.  As I said Titanium has a very bad ability to conduct heat, so once hot from