Titanium in the home shop...

[Seanol]

Had some time to work on my Cusader WIP and decided to machine the last crankcase. Since I had broken my last insert in my boring bar I tried a brazed bar from my boring head. Worked OK but I had to keep depth of cut to .020.

Now the problem.
I had built up enough swarf to make a rather large pile in the lathe bed. While I was taking a cut the swarf was getting packed in the hole. I removed it each time but it was a consistent problem.

Titanium will burn. It will burn white hot and very quickly.

I had a small piece of swarf start up and when it came out of the bore it landed in the lathe bed. Reference the contents of the lathe bed previously and you will see a nice little bed of material to continue the the fireworks!

I rushed outside and was able to get some sand (one of the benefits of desert living) and smother the fire. :-[

Two things learned:
1.) Understand the properties of what you are machining. I know that titanium is flammable but hadn't had a problem. I should have had the sand next to the lathe to begin with to avoid the panicked rush outside!

2.)Clean the lathe bed when working with a material of this type!

Hope this helps someone,
Sean

 

[rake60]

I'm glad there were no injuries or property damage Sean!

Exotic metals can and will do surprising things.
Titanium and magnesium are probably the two most dangerous
metals to work. You will NOT put out a magnesium fire.
Best you can do is bury it is soft earth away from structures,
then dig it up every few days to see if it's still white hot.

Let's be careful out there!
Be sure of what you're working with!!!

Rick

 

[zeeprogrammer]

Not to minimize things...

I'm thinking June 23 is not a good day for machining. There seems to be several uh-ohs today. Let's try to remember this next June 23 and compare.

 

[Seanol]

Rick,
I agree. Titanium has the same properties. My saving grace was the dirt and I was able to move most of the turnings away from the fire!

I worked for a titanium company and the fines pile would steam in a rain storm. I've been told it has been smoldering since the 50's

Another thing to watch out for is grinding. Aluminum and iron have the makings of thermite so I am told!

I will be better prepared next time. Luckily there should be no more turning work on the Ti!

Zee,
I hope the 23rd is not a cursed date. Going by my recent failures you could make the argument for every weekend in June!

Sean

 

[bearcar1]

Just out of curiosity, could the fire been kindled by the usage of that carbide cutter? What is the ignition temperature of titanium? Just wondering out loud here, I have never had the opportunity to work with that exotic metal.

BC1
Jim

 

[Seanol]

Bearcar1,
I was using a carbide insert at first with no problems but it had a chip breaker (which made tight curls but didn't break any chips) but the boring bar was brazed and had stringy chips and poor clearance in the hole.

Titanium will light off at higher temps due to its poor thermal conductivity. It melts at 3000 degrees but with a small bit of swarf trapped in a hole with a carbide bit it can and will spark. From there all you need is fine swarf and poof!

When you get the speed and feed off you will:
A. Harden the outer skin and the tool will skate over it
B. Spark as you remove the chip
C. Make really nasty, stringy long chips

You need to take a fairly large cut at a slow speed and high feed rate. I was turning the snout from 2.325 to .875 and had cuts in the .030 doc at 300 rpm with a feed rate of .015, the highest my lathe would go. I noticed that the bigger the bite the cooler the material (but the hotter the swarf). I used soluable oil for machining.

If I had to do it again I would wait until I get a new insert. With that boring bar I was at .030 doc at 190 rpms and same feed and I got tight little spirals that exited the headstock from the back and looked like spagetti on the floor behind the lathe!

Boy am I glad I didn't have a fire in the headstock!

Sean

 

[rake60]

Titanium will burn at a low temperature.
OK, it doesn't really "burn".
You can throw a solid chunk of titanium into the hottest fire
you can build and nothing will happen. The hazard is in the fine
stringer chips. It doesn't take a lot of heat to get those fine bits
to burn. Once they are burning there is no chance of stopping the
chemical reaction. It is an uncontrollable oxidation of the alloy.
When the parameters of heat, oxygen and fuel meet their perfect
balances, you are helpless to defeat them.

Titanium is bad, magnesium is worse!

Rick

 

[arnoldb]

This might sound like a silly question....

Would a CO2 extinguisher put out a titanium/magnesium fire ? It would take away both oxygen and heat...
That would be a good sight better than dumping sand on machinery

Regards, Arnold

 

[Foozer]

This might sound like a silly question....

Would a CO2 extinguisher put out a titanium/magnesium fire ? It would take away both oxygen and heat...
That would be a good sight better than dumping sand on machinery

Regards, Arnold

Sand dry sand at that. Better a dirty machine than burnt down shop. Did once light some of those shavings from those magnesium fire starters, sprinkled a bit of water on it and it did exactly opposite of going out. Was one of those teach the kids lessons about fires. Do not try this at home

"Since magnesium burns in the presence of carbon dioxide, a CO2 fire extinguisher does not put out the flame from burning magnesium; a dry-chemical fire extinguisher must be used instead." http://www.angelo.edu/faculty/kboudrea/demos/burning_magnesium/burning_magnesium.htm

 

[arnoldb]

Thanks Foozer

Note to self: Basic fire-fighting principles does not apply to all volatile metals/chemicals! - Maybe I should have paid more attention to chemistry lessons in school!

Clean-up job between sand & powder extinguisher... Sand on one machine or powder dust through the entire workshop; it just might be easier to clean the sand then ;D - I've had to clean powder from a building and that is no fun!

Regards, Arnold

 

[bearcar1]

Thanks for the information re: the feed rates and speeds Sean, I think that I will not likely be working with the big 'T', shoot, I have troubles enough working with CRS sometimes :big:
Fire safety in our shops should be addressed and we should all be prepared for something like your experience to happen, even though we think it won't. :bow:


BC1
Jim

 

[Seanol]

Guys,
I have a 13 x 40 or so machine. It has a bed well below the ways. Sand was placed(thrown! ;D) in the bed below the lathe. The real problem was all the other swarf(fuel) that I didn't clean up. Had that caught I might have had a different outcome :'(

Should have listened to that inner voice...

Sean

 

[Camsfirie]

It is very misleading and dangerous to say that “a dry-chemical fire extinguisher must be used instead” on Class D combustible metal fires. The writer has confused dry chemical with dry powder extinguishers. They are NOT the same!

Dry chemical extinguishers contain sodium bicarbonate, potassium bicarbonate or ammonium phosphate.

Dry chemical extinguishers are suitable for Class A (solid substances such as wood, paper, coal, rubber), Class B (liquefiable solids such as petrol, kerosene, methanol, oil, paint, grease) or Class C fires (flammable gases such as LPG) but NOT Class D fires involving combustible metals, such as magnesium or titanium.

Class D combustible metal fires require dry powder extinguishers and work by simply smothering the fire.

Carbon dioxide, foam, and dry chemical extinguishers are not effective on titanium fires, but good results have been obtained with extinguishing agents developed for use on magnesium fires.

The most common extinguishing agent for use on Class D fires is sodium chloride (NaCl - common salt). You should have in your shop an approved class D unit if you are working with flammable metals.

Sodium chloride dry powder extinguishers work well for metal fires involving magnesium, titanium, and powdered aluminum. Heat from the fire causes the agent to cake and form a crust that excludes air. As long as the crust remains undisturbed the combustible metal will not reignite. The Sodium chloride will dissipate heat; however, the combustible metal (particularly magnesium) will be slow to cool and may remain hot for from 90 to 120 minutes after extinguishment.

The safest procedure to follow with a fire involving small quantities of titanium machinings is to ring the fire with a Class D extinguishing agent and to allow the fire to burn itself out. Care should be taken to prevent formation of a titanium dust cloud.

I write the above as a firefighter with 37 years experience with aircraft fires and a senior firefighter at Formula One races for the past 15 years.

 

[Seanol]

Camsfirie,
Have you ever heard of using soda ash for titanium?

Good call on the Class D extinguisher. I will be procuring one immediately!

Thanks,
Sean

 

[Camsfirie]

Hi Sean

Yes, soda ash (sodium carbonate, Na2CO3) Class D agent is used in areas where stainless steel piping and equipment could be damaged by sodium chloride. It is used to control fires involving sodium, potassium, and sodium-potassium alloys, but it has very little use with other combustible metal fires and I have never used it in my career. Sodium chloride is the agent of choice on alkali metals including magnesium, titanium and aluminum because it is effective and cheap and it can also be applied to a metal fire with a scoop or a shovel.

So, in addition to the the 9 litre AFFF and 9Kg monoammonium phosphate dry chemical extinguishers in my workshop I have a 10 kilogram drum of sodium chloride that can be applied to a metal fire with a shovel. They are mounted in a visible position close to, but not on top of, the areas they are designed to protect.

 

[1Kenny]

http://en.wikipedia.org/wiki/Purple-K

 

[Seanol]

Camsfire,
Thanks!

Since this may not be a one off I will get some soda ash to supplement the Class D. I do not plan on any magnesium anytime soon.

Appreciate the info,
Sean

 

[steamboatmodel]

Camsfire,
"The most common extinguishing agent for use on Class D fires is sodium chloride (NaCl - common salt). "
What type of salt, Table or Rock
Regards,
Gerald.

 

[Camsfirie]

Table salt form.

The sodium chloride needs to be in the finest form so that it can flow freely from a stored pressure extinguisher bottle, siphon tube, hose and applicator. The extinguishers have a special very low velocity applicator to ensure the sodium chloride is applied efficiently and effectively to the burning metal and prevent burning swarf from spreading by being blown around by propellant nitrogen gas.

When being applied with a shovel the table salt form ensures that the sodium chloride flows well to ring the fire and if applied over the burning swarf it flows to form a good seal over the fire.

 

[THX-1138]

Would a CO2 extinguisher put out a titanium/magnesium fire ? It would take away both oxygen and heat...
That would be a good sight better than dumping sand on machinery

Looong time later: The short answer is "no." Here's the long answer:

[ame=http://www.youtube.com/watch?v=WoBp2m035OA]http://www.youtube.com/watch?v=WoBp2m035OA[/ame]