3d metal printed sculptures

[www.bathsheba.com]

It is a commercial/patented process that the artist uses.

Some interesting ideas in it though.

"To start with, the design is laid down, one layer at a time, in stainless-steel powder held in place by a laser-activated binder. You can see the layering on the finished pieces, it is the source of the characteristic texture of my work. Each layer is .004" to .007" thick. "

"After the whole model is built up, and the extra powder is shaken off, the piece goes into an oven, where heat drives off the binder and fuses the steel powder. There's just enough heat to make the granules weld together where they touch, without collapsing the entire piece into a puddle. This produces a porous steel part that's about 60% dense, like the one at left. "

and especially this part:
"To do this the model is heated again, the stems are dipped in a crucible of molten bronze, and capillary action causes the bronze to wick throughout the piece."

That's so cool!!
I am allready looking into resins with metall fillers for making conducting polymers (mainly aluminum) but this technique you found has some real kick-ass potential!!

The process is called Selective Laser Sintering (SLS).

If you use a laser to directly fuse a powder it's called Direct Selective Laser Sintering.
If you use a laser to fuse the binder portion of a mixture of a poweder and a binding agent it's called Indirect Selective Laser Sintering. Sometimes the binding agent is a coating on the powder grains, sometimes it's a separate powder. I imagine buying special coated powder is from a SLS Printer manufacturer is impossible.

I've been looking around for a way of doing Direct SLS in a manner that's convenient for us. I saw a paper a while ago about doing aluminum powder in atmosphere. I'll see if I can dig it up.

Here we are:
[stinet.dtic.mil]
This uses powdered alimna (Al2O3) and powdered aluminum. The aluminum acts as the binder, fusing the alumina particles together. This is done in normal atmosphere, which means we wouldn't have to build a nitrogen glove box or vacuum system.

The process does have a few caveats. My alma mater has one, so I've seen it in action.

The polymer covered metal powder is (probably) expensive. I can't think of a method right now to duplicate it "at home". Plastic powder itself could be used for non-metalic work.

The system works based on having two beds that move powder between them as it builds up. This would not be difficult, but it's not a core discipline of RepRap, would probably be a bit messy, and you'd have to clean up and break out the part from the powder. Still, no need for support structure.

The biggest issue I see is the laser. It's a multi-watt output CO2 laser. This means big and heavy, although not unreachable (people make these at home but not for constant run). RepRap would need an optical positioning system and redirect the beam instead of positioning the laser physically. Plus a bed to take it. The advantages of the laser is that it can be VERY accurate both in width and in depth of fusing. This is the issue with using a real physical head to heat a built up layer system. I don't think it's feasible to put that much heat into a spot any other way.

Wait, you say this is a laser that evaporates the polymer away and melts the metal powder? I though that part was baked in an oven.
I can think of a polymer that easily evaporates, like polystyrene (no the expanded sort) that you could fill with any metal powder. If you can get this to bake in an oven in a way that the metal particles melt together, you don't need the laser anymore.
If you chose the right metal powder like Messing or Zinc, the oven temperature can be pretty low (+/-400

Edited 1 time(s). Last edit at 05/17/2007 06:02PM by Fernando.

No, the laser melts the binder, and the binder then flows into the gaps between the other particles (hereafter referred to as "structural" particles) and glues them together. (In Indirect SLS).

After this, you can do postprocessing, like (1) dip it in some material that infiltrates the gaps between the structural particles, like bronze or maybe cyranoacetate (superglue), or (2) pack it in alumina powder and fire it in a furnace, which will burn off the binder and then sinter the metal particles together. In method (2) there is probably some shrinkage.

We may be able to make metal objects by preparing a mixture of thermoplastic and structural powder, like ceramic or metal, say 10/90 proportion by weight, building up an object this way with a normal RepRap with a syringe head, and then take the object and fire via process (2). This process would be very easy to experiment with.

I think we'll have a number of different research threads in parallel. I'm excited about working on the laser side of things, because, dude, laser!

hahahaha.... dude. laser. love it!

Yeah, laser has that... sci-fi appeal

stuff like this may be helpfull?

From a DVD burner diode:
[www.felesmagus.com]

Crazy Laser sites with manure-loads of info!

[www.repairfaq.org]

[www.geocities.com]

I have to bump this thread

Direct Metal Laser Sintering - DMLS