[dmac257]

I was thinking about space-x and the possibility of building in space. A search of welding mentioned several welding experiments in the long ago past (1969 and 1973) but it seems the experiments were gas shielded in microgravity. There are several experiments again on board planes and in freefall drop microgravity but again with gas shielding. It occurred to me that if you were welding in a vacuum you wouldn't need the shield gas but has any such experiment been conducted. I couldn't find it. Does anyone know of a paper describing welding in a VACUUM in space?

dmac257

[LtBadd]

Interesting, I don't know of any such research but then I haven't looked.

I could be wrong but I believe the "vacuum" of space isn't so empty, and don't know if, say a tig setup would work, putting aside all other possible issues that may go along with such a thing

[ljdm1956]

Would you even have a flame without oxygen in a vacuum? Deep stuff to think about.

[ex framie]

Micro gravity would raise some issues, shape of the puddle might be interesting, crap floating around etc.
Also the extremes of temperature 200 plus in the sun, near absolute zero in the shade, micro cracking anyone?
Also trying to weld in the gloves of a space suit with dome reinforced finger tips, that would come close to the 7th level of hell.
Someone somewhere must have done a few experiments, which is probably why everything that gets built in orbit is modular and just needs assembly, even bolts are a nightmare.

[Arno]

Does anyone know of a paper describing welding in a VACUUM in space?

Can't help eith a paper, but get metal surfaces polished and close fitting enough and it will cold-weld in vacuum if pressed/rubbed together hard enough

None of those pesky gas molecules from an atmosphere keeping surfaces apart and the atoms in the metal have no concept of being on a 'surface' or not so put 2 surfaces tight enough together in a vacuum and they basically 'become 1'.

Techniques like electron-beam welding are of course already done in vacuum chambers here on earth.

For a manual process in outer space I suspect it's going to be easier (although still very difficult ) to actually make use of the specifics and advantages of the environment like hard vacuum and low gravity than to try to 'transplant' methods that work here on earth which are designed/developed to work around issues like oxygen-rich atmosphere and the like.

Although any conventiolal arc-welding would immediately run into 1 issue in a hard vacuum: no gas, no plasma to carry the electrons and ions, no arc, no welding..

But then in a vacuum you could make direct use of electron beam 'guns' and likely also things like solid state laser units to directly heat/weld the parent material as there's little or no atmosphere to interfere like here on the surface (where an electron beam gun out in the open is useless..).

A few ppm gas molecules out there (of which there's a relative lot of helium and hydrogen of course and much less heavier ones) would likely not be a major issue for most metals except some like high grade titanium..

(micro)gravity is likely the most tricky bit from a practical standpoint as floating blobs of molten metal are probably bad news

Bye, Arno.

[Lightning]

Would you even have a flame without oxygen in a vacuum? Deep stuff to think about.

In an oxy-acet rig, the oxygen is supplied by the oxygen bottle, not the air.

As for shielding gas...in TIG, in addition to shielding the weld puddle, the shielding gas also provides a vehicle (plasma, which requires an ionizable gas such as helium or argon) for the electrons to travel between tungsten and work. So you would still need argon or helium (or whatever) in the vacuum of space.

Also, the "vacuum" of space isn't entirely empty. The gas molecules are just a lot further apart than in the air. So there will still be contaminants that can get into the puddle, just less of them...

[dmac257]

Does anyone know of a paper describing welding in a VACUUM in space?

Can't help eith a paper, but get metal surfaces polished and close fitting enough and it will cold-weld in vacuum if pressed/rubbed together hard enough

<CLIP>

But then in a vacuum you could make direct use of electron beam 'guns' and likely also things like solid state laser units to directly heat/weld the parent material as there's little or no atmosphere to interfere like here on the surface (where an electron beam gun out in the open is useless..).

A few ppm gas molecules out there (of which there's a relative lot of helium and hydrogen of course and much less heavier ones) would likely not be a major issue for most metals except some like high grade titanium..

(micro)gravity is likely the most tricky bit from a practical standpoint as floating blobs of molten metal are probably bad news

Bye, Arno.

Hard to guess what type of welding from a "concept video"
https://www.youtube.com/watch?v=TmLWxptFFYc
bit after 7:55 shows construction with robotic welders .. the Remote operated robot directing the placement is kinda funny cause you would just remote operate the robot moving the module not make hand signals to one.

I guess it could be electron beam welding???

dmac257

[Sandow]

Welding in vacuum environments is a mixed bag. True, you don't NEED shielding gas but boy do you ever want it. A naked arc in vacuum kicks out all kinds of stuff including Vacuum and Extreme ultraviolet with a sprinkling of hard X-ray for good measure. Arc wonder is also an issue without a plasma channel formed for consistency. Lastly, the gloves worn in EVA are like the big silicon oven mitts in terms of dexterity. Go try and feed rod like that lol... Nasa did testing on it and found that a 2 LPM flow of argon was adequate to allow fairly normal operations of welding gear in fairly hard vacuum (10^-5 Torr).

-Sandow

[nelson]

Very interesting. Very interesting..
Fractionation of "slag" in zero g.
Whole bunch forces to consider.
Shielding? Arc control?

Wow for short.