Machining pure Tungsten?
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RoninB4
Well-known member
-Details? What have you already found? I've milled and turned a couple of things from an alloy (Tantung-G) and it wasn't fun.
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RoninB4
Well-known member
-Likes to chip, likes to fracture, doesn't like being dropped, likes to wear out tooling through abrasion. If that's all you have for details then will a hammer and chisel work for you?
RoninB4
Well-known member
-Well I sorta presumed it would need a bit more precision but resorted to the absurd to draw out details, which are still lacking feature description. ID grinding the internal radius of a clevis? No info, no comments.
-Not asking for more than you want to divulge but this is like pulling teeth. Rotab may/may not be a good choice but nobody else will ever know except you at this rate.
Why so hostile Ronin. Was just asking if anyone had any tips. I’ve never worked with this stuff before and just asked if anyone had.
Im just going to treat it like graphite I suppose. Minimal DOC and probably keep it flooded with WD-40.
Is it a bad thing to ask if anyone has useful advice before tearing into a $4k hunk of stock!
Im just going to treat it like graphite I suppose. Minimal DOC and probably keep it flooded with WD-40.
Is it a bad thing to ask if anyone has useful advice before tearing into a $4k hunk of stock!
I kinda think this might be fun! Till it isn’t. Will definitely be messy!
Need to cut the 6” bar into 2 pieces. A bottom and a lid. Will most likely have about a 3/8 x 3/8 lip interface. Will then bore around a 3/8” hole into the bottom half about 2.25” deep. That will have a copper part hopefully press fit into it with a .200 bore in it. I’m really not keen on making this a press fit. Think I might make it more of a slip fit with some super glue. And a copper disk fitted into the underside of the lid. That’s about all the details I can provide at this time as I haven’t actually drawn the parts up yet.
And yes it is a pig for radiation shielding.
And yes it is a pig for radiation shielding.
RoninB4
Well-known member
-No hostility intended. What I was trying to convey was semi-humorous, rib poking sarcasm but this is the limitation of the internet. A mild annoyance might have colored my wording.
-I understood the reasons you posted, nothing wrong with asking questions either. Your lack of details did cause me to wonder if you were asking for info or just taking a survey. If you want info you have to provide some context regarding machines, tooling, and a rough description of the features needed. When the short question is "Has anybody done this?" the short answer is "Yes/No". I regard the work you're doing as interesting. Throwing out a short question like the thread title has me taking the bait. When I asked for details and what you might have already found the reply was so very minimal as to suggest you wanted an equally minimal reply. Perhaps I should have just replied "Not pure tungsten, just an alloy" and left it at that instead of attempting to prompt/prod you for further details/info. No hostility was intended, I try to just disengage when it arises. You and I don't have lingering resentment and I see no reason to start now.
-I've turned, milled, and ground a fair bit of graphite but my reading suggests tungsten to be far more abrasive and fracture prone. Nobody seemed to enjoy working it and many refused to bid on the job. One member reported that it was easy enough to machine but chewed his spade drills quite a bit at the corners.
-I didn't note the speeds/feeds since your details weren't posted
-Well of course it isn't a bad thing, especially with an expensive and unfamiliar material like tungsten. What I don't particularly understand is why are you not asking advice from a site like PM? They're a cranky bunch but the depth of experience is considerable. It would be good to draw from previous experience because It's been reported that there doesn't seem to be a market for scrapped tungsten pieces. Perhaps this is due to it being fracture prone and nobody wants to take a chance with an potential flaw. Cutters with sharp corners abrade. Radii instead of sharp corners are reported to last 3x as long. Like you said, it might be fun until it isn't.
RoninB4
Well-known member
-The grade of carbide you use will likely affect the process and results. Cheaper carbide from China is probably a waste of time for this material. Coated carbide? Unknown whether it makes much difference or not. Some have reported using diamond/CBN inserts to avoid excessive wear/abrasion. My experience with the alloy was somewhat limited but for turning, milling, drill/tap, and then precision grinding the material chewed on everything. Whatever subtractive tooling you use I would plan on having multiples of. There's also EDM but that adds expense, compare it to conventional machining.
-With tungsten being fracture prone I wouldn't expect success by stressing it with a press fit.
-Will it be subjected to heat?
-Dimensions less important than the process to get there. How you hold the work without stressing it will also deserve some thought.
-Another reason, besides machining flaws, why tungsten components don't sell. I wish you success with this.
Thank you. Not exposed to heat. Appreciate your input.
rlitman
Well-known member
Can't say I've machined anything like you're dealing with, but I have a bit of experience dealing with tungsten TIG electrodes. They like to splinter and spall, but grind with diamonds pretty nicely (easier to work than granite or porcelain tile). A lot of your experience will depend on the manufacturing process, because it's not like anyone casts liquid tungsten (what would you even use for a crucible?), and I've seen good variations in behavior between packages of rods (assuming because they're made by different companies). Yeah, "solid" tungsten is spendy, but alloys with iron (typically around 10% iron) are routinely machined (often used for dart bodies). I'm curious how the purity of your material will change this, but expecting it to be for the worse, kind of like how brass is harder to machine without lead.
As for a press fit, I'd be uncomfortable with the hoop strength of the tungsten. Even with adhesive, I'd leave space for the copper to thermally expand, and use an adhesive that accounts for this movement.
As for a press fit, I'd be uncomfortable with the hoop strength of the tungsten. Even with adhesive, I'd leave space for the copper to thermally expand, and use an adhesive that accounts for this movement.
A quick update. Chucked up and faced in the 13”’colchester. Brazed carbide tools did cut it, but pretty bad finish. Had some diamond tools that worked pretty well. Was only taking a 0.010” cut @ 350rpm with a slow feed and using way oil as fluid.
Threw it into the horizontal saw and made about 1/2” cut into it with a bimetallic blade with coolant Same blade cut Titanium and Zercaloy just fine, figured it was was worth a shot. Kinda expected. Have a carbide impregnated blade coming from McMaster tomorrow.
I knew this was going to ****!
I’ve read that this stuff likes to be machined better if it’s at 450degress. I’d like to figure out how to do that!
Anyway thanks for all the good luck wishes and if anyone has any suggestions on on this hell metal please speak up.
Thanks.
Threw it into the horizontal saw and made about 1/2” cut into it with a bimetallic blade with coolant Same blade cut Titanium and Zercaloy just fine, figured it was was worth a shot. Kinda expected. Have a carbide impregnated blade coming from McMaster tomorrow.
I knew this was going to ****!
I’ve read that this stuff likes to be machined better if it’s at 450degress. I’d like to figure out how to do that!
Anyway thanks for all the good luck wishes and if anyone has any suggestions on on this hell metal please speak up.
Thanks.
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mike93lx
ALLIANCE MEMBER
Will any heat help or does it only start to help at 450?
O/a torch hose clamped to your tailstock?
Not really sure. My first delve into this material. I’m not really sure how that’s done. I was thinking more possibly on a mill than a lathe. Either way I don’t really want to be standing next to it!! If I continue to work with this material I’m pretty sure the edm shop down the street will have more business.
rlitman
Well-known member
You don't want to heat tungesten with O/A. It likes to turn into tungsten carbide.
mike93lx
ALLIANCE MEMBER
Electric furnace only?
rlitman
Well-known member
Why do I feel like this is going to turn into the worlds biggest lightbulb (at least momentarily)?
RoninB4
Well-known member
-Gee only 9 hours?
-I'm a tad disappointed to hear this. Think of all the hours of entertainment you'll be missing by sending it out. I was all set to read progress reports on further machining operations, even had a bowl of popcorn ready..... (said with tongue firmly in cheek)
Grant Gunderson
Well-known member
If the EDM shop is reading this, their quote just went up 100000x haha.
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RoninB4
Well-known member
-The cost of education is seldom a bargain but the experience is often priceless. painful, or both. At least you tried.
That’s why I asked in the first place. At least the band saw pretty much runs it self so I was able to get other things done. Out $250 for the blade. Think I might have made some new friends at the EDM shop. Hopefully have an estimate tomorrow!
Right
So they need to make at least 1 electrode, probably 2 if you're doing a cap and maybe even 3.
Plus EDM time.
Curious why you need a tungsten containment vessel...
rlitman
Well-known member
The usual reason is that it's better than lead at blocking gamma radiation. Last time I've seen something like this was a tungsten cylinder that wrapped the syringe holding the FDG when I got a PET scan.
Yep, it’s going to take a while.
Tungsten shields about 1.75 X better than Lead. So we can have a smaller lighter pig vs lead. This thing is going into containment of an operating reactor. So anything that makes that jump easier/safer/faster is worth doing.
This tungsten pig weighs about 30lbs. The equivalent in Pb would be around 70lbs. And needs to be transported on catwalks and up/down a couple sets of stairs.
Tungsten shields about 1.75 X better than Lead. So we can have a smaller lighter pig vs lead. This thing is going into containment of an operating reactor. So anything that makes that jump easier/safer/faster is worth doing.
This tungsten pig weighs about 30lbs. The equivalent in Pb would be around 70lbs. And needs to be transported on catwalks and up/down a couple sets of stairs.
RoninB4
Well-known member
-Yeah I'll bet they're happy to talk with you but that's just the nature of things sometimes.
Makes sense.
But I assume there's established companies that make those.
No offense to OP, but it seems like his company is just stumbling along with some things that may be basic in their industry
rlitman
Well-known member
For syringes, there are several options on the market you can order, with or without lead crystal windows. For a custom sized fuel capsule for a prototype reactor, finding something COTS that does the job well enough may not make sense over a one-off custom. Especially when you're considering future scale up.
I'm sure he's considered that before coming here. I'm also quite sure we don't have enough information to make that call, but it still is fun to think about.
You would think so. And we have lots of very knowledgeable people in the field working for or with us. But what we are doing has never been done before and we are working with some very nasty stuff. I’m alwas the first one to employ something off the shelf! But for this it simply doesn’t exist.
It’s way too specific. I was actually very surprised to even find off the shelf stock this large.
So at the end of the day we will have >$5k into this little cask. But the little sample that it will carry will be worth >$1mm and hopefully save the lives of many cancer patients. And we can reuse the cask many times (as long as no one drops it!). I just found out today, now they want another one! I’m very curious what the EDM shop is going to charge!