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TANTALUM - has anyone machined it?

ScorpaF

Plastic
Joined
Feb 4, 2009
Location
UK - NEWCASTLE
I'm busy looking at some components made from Tantalum - has anyone machined this (turning - milling - drilling) and got any good data regarding speeds, feeds, inserts etc. I'm guessing its going to be not unlike Inconel but if anyone has any hard data it would be much appreciated.

Thanks in advance.
 
Be careful, this is from a safety data sheet for tantalum;

PHYSICAL HAZARDS: Extremely flammable. May ignite spontaneously on exposure to air. Dust/air mixtures may ignite or explode.
 
Funny you should mention this. The other day a guy in my shop was drilling holes in some material that had Tantalum in it. It was a small hole about 1/8th dia. he had it in a Hardinge lathe. He was using a carbide drill and he was showing me how the chips would suddenly ignite and disappear in a flash! He said the stuff was a "bitch" to machine. He reminded me we had milled the same stuff about 2 years ago with similar problems. Martin
 
I'm busy looking at some components made from Tantalum - has anyone machined this (turning - milling - drilling) and got any good data regarding speeds, feeds, inserts etc. I'm guessing its going to be not unlike Inconel but if anyone has any hard data it would be much appreciated.

Thanks in advance.

The only use I know of Tantalum was when I worked for the government. Expensive and hard to get, gummy and tear’s. Good luck, because the guy that cut it the most didn't like it at all.

What are you doing with it?

Tom
 
Tantalum

I think Tantalum is a lot harder to machine than Inconel. It's been a long time since I worked with it. but I remember we had to use a chemical as a cutting fluid. We brushed
it on and it had a bad odor.The chemical was something like carbon tetrachloride but not as bad. I don't know if anyone here remembers using carbon tetrachloride as a cutting fluid.
It machined about the same as molybdenum.
Jim
 
Cutting fluid

I used to work with an old machinist who worked with tantalum when he was at Varian Vacuum. All I remember him saying about it was after much trial and error, he ended up using Listerine mouthwash as the cutting fluid. YMMV

Davis
 
Jims has the right of it. Tantalum is very much like Molybdenum.

Dense (heavy), gummy, and expensive as hell.

Hard to get a good surface finish on it.

I highly recommend the link toadjammer posted. I wish I'd had that info back when I was working with Tantalum several times a week.

As far as it's being flammable ... I don't think so.

I believe you have confused it with Titanium.

Much more info here:

http://en.wikipedia.org/wiki/Tantalum
 
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25 years ago we received a piece of Tantalum from the Navy Research Center. The piece we received was a piece of plate that looked like it was broken off a larger piece. They wanted us to try and cut it with an abrasive waterjet. We did cut it and never heard anything else from them. The waterjet did a great job.
 
I stand corrected sir.

Shoulda/coulda looked first.

Also found these:

Combustible. Dry tantalum powder may spontaneously ignite on contact with air.

and

An accidental tantalum powder deflagration with casualties occurred during the operation of a bag filter dust-collecting device. To understand the mechanism of the incident and its material hazards, experiments for determining the combustibility and ignition characteristics of the tantalum powder were performed. The magnitude of the tantalum dust explosion is classified as severe (Kst=273), contrary to the classification found in the preceding literature. The minimum ignition energies for both a dust cloud and a dust layer of the tantalum powder were also found to be far lower than previous values. Judging from the observation of the surface with an SEM, the coral-like structure of each particle of the tantalum powder can enhance its fire and explosion hazards and affect its sensitivity to electrostatic sparks by increasing in particle surface area. A thin, non-conductive oxide layer of the tantalum powder surface has a high resistivity and generates electrostatic charge when rubbed with conductive materials like the wall of the collecting device. The authors conclude that the possible cause of the ignition was electrostatic discharge resulting from charging electrostatically.

Kinda hard to reconcile with:

The oxide is used to make special high refractive index glass for camera lenses.[35] The high melting point and oxidation resistance lead to the use of the metal in the production of vacuum furnace parts.

and

The metal is highly biocompatible and is used for body implants and coatings, therefore attention may be focused on other elements or the physical nature of the chemical compound.

It does say "dry tantalum powder" though so machining it and using a coolant/cutting oil shouldn't present a problem.

Never did for us ... unlike Titanium and Zirconium.

All kindsa' excitement when someone let's their lathe run out of coolant turning a bar of that at high SFM with a pan full of chips!

Not me BTW ...

Thank you for the information.
 
But what doo you doo with the chips then?

Mix them in with the others? Possibly start a farr in the chip bin? (Rusty steel chips will self ignite as well.)

Throw it in the dumpster and light the gas at the landfill of farr?



------------

Think Snow Eh!
Ox
 
I am not at all questioning the flamability of Tantalum and would recomend all proper precautions be taken, but...

I work in a lab, so I have read MANY msds sheets for various substances and it is very helpful to have other sources of information than the msds. One of the points of the sheet is to point out the worst case scenario, and as such can be a little exagerated from reality. Depending on the source the msds for water makes it look like deadly poison.
 
I'm busy looking at some components made from Tantalum - has anyone machined this (turning - milling - drilling) and got any good data regarding speeds, feeds, inserts etc. I'm guessing its going to be not unlike Inconel but if anyone has any hard data it would be much appreciated.

Thanks in advance.

I have been machining tantalum for some time now. It was a trial and error thing but I have established methods for it over the years yielding great results. I have 2 jobs I have been making for years that require turning, drilling, and threading. All with very close tolerances and that also require very good surface finishes. I use 35 SFM for all ops. I use only HSS tooling as the material wants to tear and HSS is what I can get the sharpest edge with on the tool. I have to grind a very aggressive chip breaker on the turning tool and you want absolutely no tool nose radius. I know this sounds odd but this is the only material I cut that actually does not leave a threaded finish while cutting with no tool nose radius. I take .040 for roughing passes and .010 for a finish. I use CRC true tap for a cutting fluid and use a light drip application and make sure the tool does not run dry. I feed at .004 IPR. The cut is flawless and there is absolutely no burr at all. If it starts wadding up, your tool tip has broken.

I then have to drill a .035 hole through the part that is 1.000 long. This is a tough op but I do it. I use the same SFM and have to take very small cuts. I use the same cutting fluid and it cuts really good. I just have to be careful as the tiny drill breaks very easily. I peck every .004. Time consuming but it gets the job done.
 

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Jason,
It's a 7 year old thread. If they haven't got it figured out by now, they're in deep shit!

Nice work on the part though! I alwasy envied you guys that could hold finished parts.
JR
 
Great information Jason. Thank you for sharing.

And I much appreciate reviving an old thread rather than starting a new one on the same topic. It shows that you did your home work! It simplifies the search and read process. AND... It makes posting links to those old posts redundant.

Good show!
 








 
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