NASA: EBF3 - Electron Beam Freeform Fabrication

[www.nasa.gov]

is there any way we could see something in that direction in future models?
I know there were some plans on Metal printing. But melting a wire with an electron beam sounds like a creative idea.

The article spends a lot of time explaining the process of building parts from layers, but doesn't say much about the unique part of the process: the use of an electron beam to melt metal. Can anyone offer some information?

Well first off you need a vacuum chamber and the process generates XRAYS so you need shielding so you don’t get a fatal dose of radiation; then you need an electron beam source of 8,000 to 60,000 volts.

Not quite something to run on your desktop.

For more information just type "Electron beam freeform fabrication" into google.

For stronger structures a more reasonable near term possibltiy for us is:

[dev.forums.reprap.org]

Edited 1 time(s). Last edit at 10/03/2009 12:19PM by freds.

That's what I was somewhat worried about. X-rays are annoying. Now, an X-Y stage in a bell jar isn't too implausible. DO NOT DO THIS, however the interior of a CRT screen is exactly this. High KV electron beam gun, lead shielding, but it uses magnetics to steer the beam. That, however, is a different RP system (electron beam used on a metal powder bed). Keeping a seal is difficult if you are feeding the metal into the build chamber from the outside.

I do like the idea, just not certain how practical it will be.

Ahh a use for old TV's, just have to up the beam current LOL!

Anyway want to do the power calculations?

The NASA version creates a puddle of metal verses exciting phosphor dots, but since you are recycling use multiple guns with a raster image?

Maybe. 32" TV's routinely have something like 90W input per some power calculations I found online. So we're talking probably 20-40W directed at the screen.

That could possibly do it if you moved away from a raster scan and have some form of header on the wire feeder.

Then you into the mechanics of a vacumn chamber and pulling enough vacumn that the gun doesn't vaporize it self, etc.

Maybe part of the construction is step one, get 12 lead acid batteries for the safety cage.

You could abandon the electron beam, and the vacuum chamber, and use a welding rod to draw patterns of gloppy molten metal for each layer. It would use a lot of welding rods, and not have much resolution, but it would be simpler.

I actually have an interesting idea about how to do this. The first time I came up with the idea, it involved using a huge electro-negative potential and a microwave gun to excite an air plasma where the electrode gets eroded as feed stock and big magnetic coils push the plasma stream around.

Then I learned about plasma cutters, which skip all the messy microwave parts and just use a spark gap and compressed air to push high current/high voltage around. Basically the idea is to again use the electrode as feed stock and use some sort of magnetic coil setup to push the plasma plume around. It would be messy, but for large enough objects it could be an interesting way of making precision metal parts.

The neat thing is that it actually could be a desktop sized metal fabricator, except it would need some sort of ventilation control and need to be isolated from users as it would be like having a microwave oven. You don't have the option of running a microwave oven with the door open and the cover off, or at least I hope not.