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Turning Tungsten

I vaguely recall machining what I think was pure tungsten, to be used as an EDM electrode. This was a looooooong time ago, but dont remember needing any special tools or having problems. The chips were very short and irregular, like cast iron, or magnet material. Brittle stuff, too, IIRC.

...memory poor...C-R-S...must take more ginkgo bilboa?
gecko balboa?
Rocky Balboa?
:confused: :(
 
I made alot of balance weights, and one boring bar. I don't remember treating it any different than mild steel for manual machining.
 
I know of a company that regularily machines tungsten, primarily milling. They were able to get it to machine like 304 stainless by heating it to 450F. They built special vises with heating elements and lightly brush peanut oil on it. I know your turning it so heating is just about out of the question but I thought I'd pass on the info.


Jim
www.pivotlok.com
Professional Bench Top Work Positioning Systems
 
It machines like tough cast iron. Don't push it too hard or high RPM.
I used to make some small 5/8 dia parts on a Hardinge, it was quite painless, but be careful if you need to tap it. Use 2 fl or NI taps that have a strong core.
 
Tungsten is not hard, but it is tough. Use very sharp carbide, keep your speeds and feeds down and use lots of coolant. I don't have any problem with turning it, but pressures are high so turning on small diam stuff may be a problem. Tungsten is stringy and tends to delaminate and tear if your tools are not sharp as a razor.

TMD
 
Tungsten is really difficult to forge. An Israeli blacksmith makes heavy duty punches from Tungsten because it doesn't deform when driven into huge blocks of yellow-hot steel billets and it is essentially self-lubricating. He used abrasive machining as I recall. When he was asked where he got the tungsten, he said "the desert--armor-piercing shells are tungsten".
 
If you mean grinding, I don't know, but some carbide inserts come with a warning for grinding.
As for milling/turning, you get chips not dust that you would breathe in, so I don't think so.
 
You need to be careful with tungsten carbide dust. Solid tungsten carbide (inserts etc.) is carbide powder with cobalt metal binder, and it is the cobalt you need to be wary of. See:
http://www.osha.gov/SLTC/healthguidelines/cobaltmetaldustandfume/recognition.html#healthhazard
Tungsten metal itself is relatively harmless unless you're sitting in a tank and someone is shooting chunks of it at you. The dust should be avoided, don't breathe it in or rub it in your eyes or set fire to it.
 
Now I have a tungsten project to work on.

Does anybody have data on actual speeds and feeds that work well?

How about cutter geometry?
 
BTW, I wonder if some of you guys with tungsten machining experience might actually have experience with "machineable tungsten", which is usually semi-porous tungsten infiltrated with other stuff, such as copper, to make it easier to machine. This stuff is said to machine much like cast iron.

Pure tungsten, which is what I'm dealing with, is very brittle and difficult to machine.
 
I machine end caps for sonar detection divices for the navy regularly. it machines alot like cast but is very abrasive. usualy my sfm stays about 125-175 using kenametal kc5010 grade inserts. i try to take heavy cuts since the tool nose radius wheres off after about 6 passes at .2 deep .006 per rev and 3" long cuts. the tungsten grade is somthing like h16hd " i think" and it comes from korea. a peice 4" dia x 4" long cost us $465.00 per pc. buying 24 pcs. at a time. plus air freight. being that each pc weighs 18 lbs. that hurts too.
 
Just finished doing a couple of test peices out of what I was told was "pure" tungsten. It was just a little slug about 7/8 long. Had a head about 3/4 dia by 3/16 long and the rest was 5/8 dia. Had to thread the 5/8 area 5/8-18. I gotta tell you this stuff is tough and abrasive. Tried single pointing,thread grinderand thread milling. Seemed like the stuff didnt want to come apart. The point of the tool just wore off right away,had that bright burned off look to it,like I was cutting on a dowel pin. Also couldnt keep the thread grind wheel sharp enough on the nose to avoid root radius problems.It turned nice, like hard cast iron or plasma spray but it is abrasive.
 
Thanks for the info, guys.

So far, almost everything I've read has been on using carbide for machining tungsten (there was one study on the use of PCD tooling for face contouring of porous tungsten). I'm kind of wondering about the applicability of ceramic tooling. I don't have any ceramic experience, though. Does anybody have any thoughts on this?
 








 
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