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This is my first post. I apologize in advance for any faux pau's. Rapid prototyping in plastic and sintered metal is already well baked, but what I propose is a slightly different approach. In a vacuum chamber most metals and many oxides can be evaporated and deposited on substrates with little or no
contamination. Many processes also require the ionization of the vapor to promote adequate adhesion. If the vapor can be ionized then it should respond to the effects of magnetic and/or electrostatic fields. The vapor could be focused to a beam, rastered and otherwise controlled in such a way to produce a very controllable matrix of deposition. Given an appropriately high evaporation rate and control fields, extrordinarily complex geometries and resolutions should be achievable. One of the more interesting advantages would be that a part could selectively alloyed in a way that is not easily done now.
EM radiation as crystal catalyst
EM_20radiation_20as_20crystal_20catalyst
[xaviergisz, Sep 10 2007]
[link]
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no idea what you are on about but then I am quite technically stupid. |
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(psst, that's pronounced "fo paw's", not "po's paw") |
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This idea sounds absolutely bakable. Of course the cost for even one part would be amazingly expensive and likely slow. |
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[po], if you know how a cathode ray tube works, then you know what this idea is. Basically, there is a stream of metal vapor that is steered using magnetic fields to deposit metal one layer at a time. |
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I leave it to you genyus's |
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[po], it's like aiming a hose at a wall, except the water is magnetic and you can control the direction by placing a magnet nearby. Add to that a very very cold wall that freezes the water on contact. Hmm... did I just halfbake the rapid prototyped ice sculpture? |
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Comment from someone who works in a wafer fab:
Thats a pretty similar idea to how they make computer chips. |
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Thank you Worldgineer for the great simplification of the idea. I should have submitted it a little better. The one thing that I think could make this valuable is the idea the one could use several "guns"or"hoses" at once to either increase build speed or create parts that are, say, titanium on the surface blended to an aluminum core structure. Parts could then be engineered to each materials strengths. Or even vice versa. |
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<note before I comment>Please take my comments with a grain of salt - I'm sure there's a lot more that goes on in vapor deposition than I understand.</nbic> |
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[sp] What I fear your time constraints will be is the thermal conductivity of your metal. You have to bring metal through two phase changes (gas->liquid->solid). To use my previous example, you'll have to use a very very cold wall or very little water through your hose or it won't freeze when it hits the already-frozen ice. While that may not be an issue at the microscopic level, it will likely be once you get to real sized parts. Of course, the size of your stream may be the limiting factor when dealing with small parts. |
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Many semiconductor devices are grown in a similar way using growth reactors, Molecular Beam Epitaxy (MBE) is very similar to what you have described. However this is considered a fast process in semiconducor terms but if you want something more than a mm thick your going to wait, a very long time. A Few microns is doable within resonable time. But don't dispair such a technique may be useful for nano scale parts! |
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I agree with Not-Arf, vacuum deposition of metals is EXCEEDINGLY slow. Given the great track record of laser sintering, stereolithography, and of course CNC, I don't see the advantage of your idea if a raster-based metal prototype is your goal. There's also the option of using stereo lith to create a mold for casting metal parts, if it's solid metal you want. |
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One thing in support of this is that rasterized deposition allows you to create "impossible objects", the classic example being a ball joint where the ball cannot be removed from the socket --it's actually bigger than the hole, and normally could not possibly be inserted into the joint, or machined in place. |
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How could you possibly start to deposit the ball in the ball and socket joint you describe, [5th]? With deposit fabrication, you need to "stick" the structure onto something else... So you can't make a discrete ball not attached to the structure that surrounds it. |
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That's the problem with deposit type fabrication - you need something to build on. Far worse than this is with complex geometries you cannot build some shapes. Imagine fabricating a cave with a staligtite hanging down, when the beam comes from above. When the plane you're working on reaches the height of the bottom of the staligtite, there is nothing to deposit onto - you're trying to fabricate something suspended in space - you haven't built the roof yet that the staligtite hangs from. <ugh - that was hard to explain - hope it made sense> |
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<from a position of complete ignorance>I imagine, [Custardguts], that you could include a disposable spacer of some kind between the back wall of the socket and the first layer of ball, and then, when finished, you could burn it or dissolve it or something.</fapoci> |
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Damn, I love this place. Go [Worldgineer]. |
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Everyone seems to think this is Molecular Beam Epitaxy (MBE), but I'm seeing it differently. |
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I think [Spare parts] want to fill a chamber with vaporised metal and selectively ionise the metal vapour (maybe using a laser) close to a substrate. The ionised vapour (e.g. positively charged) is then attracted to and thus deposited on the (negatively charged) substrate. |
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This would probably be much quicker than MBE so a big [+] |
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<shameless plug> Also it reminds me of an idea of mine (linky). |
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Could you steam cool it to speed it up? (by steam I mean anything that is a vapour at the desired temperature). |
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Ball and socket example: The socket is the base, the ball is vertically above it. The ball needs to be on an arm which curves around the socket to the base. The arm can be removed afterwards. |
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[worldengineer] Place a wood chipper near the hose and you've invented rapid pycrete construction. |
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Why does it need to curve? |
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It is an example, it can curve but doesn't need to. The word 'goes' might have been more encompassing I guess. |
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