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3-D Printing with Molten Steel (Video)
Steve Delaire is making a 3-D printer that uses steel instead of plastic. Specifically, he's using TIG welding to build up layers of steel, just as most 3-D printers build up layers of plastic. He says he's "still working it out," but eventually hopes to use 3-D welding to make larger than life art pieces that are strong enough to be placed safely in public areas such as parks, where children are likely to climb on them. Steve's blog is called Molten3D, and it's a diary of his work, including the problems he encounters and how he overcomes them. He's not the only one doing metal 3-D printing; a Texas company has even made a printed metal gun. So there's plenty of people working in the field of what we really should call "additive manufacturing" instead of "3-D printing." But whatever you call it, every year we see this kind of process being used to make stronger and more complicated shapes, using an ever-increased variety of materials in ways that have been developed since this seminal paper, Liquid Metal Jetting for Printing Metal Parts, was written in 1997. (Alternate Video Link)
Some Meta
The good:
This isn't some naval gazing blog post by someone whos opinion we don't care about babbling about how 3D printing will change everything. In fact, I didn't see anything about future implications of this technology. This is just a blog by a guy building something really cool in his garage, and I like this.
Maybe it won't pan out. Maybe it will be impractical. Maybe he'll hit some insurmountable wall. It doesn't matter, he's actually doing something! He has actually got a physical thing in his garage that he's tinkering with, and that's cool in my books.
The bad:
Bold comic-sans esq font. I'm not usually a font snob, but this is really hard to read. I actually copy+pasted the contents into a text editor to read it.
Good luck.
I was a welder for quite a while. Molten steel behaves more like water than plastic. Steel "beads up" as you heat it. Being precise with welding is very hard. Plastic behaves more like frosting when molten so it's easier to use in a printer scenario.
I think his big mistake is taking the ID of 3D printing and applying it to a martial for which it wasn't intended. I'd think he'd have better luck if he instead looked at Powdered metals: http://en.wikipedia.org/wiki/P...
In industry, they design a part, make a mold for it, press a mixture of powdered metals into the mold and then sinter it (basically the same as firing ceramics)
ooo... hey look, I tried looking it up and that's exactly how they 3D print metal:
http://en.wikipedia.org/wiki/S...
anyways, yea, that's the direction he should go. I'd use electro static charge to hold the shape and then use something like an Xray laser to melt/fuse/sinter it.
I saw a demo, around 2003, of a sintering machine the military used to build prepare parts in the field. Rather than shipping a part they could produce and machine it as needed remotely; all they needed was the appropriate instruction set and they were good to go. When I asked abut the strength and durability of the parts they said it was as good or better than normal spares.
I'm a consultant - I convert gibberish into cash-flow.
Well take the bait out of your mouth and abate your breath, but please not for long. It's not that mass-produced things will be cheaper by the piece to the consumer - it's hard to compete with lost-wax, styro molding, sand casting, injection molding, etc and the cheap labor to do them. But if you need that first one made, you can get access to 100 micron precision on shoebox-sized builds for the cost of a week or two of a decent salary. Which can save you time and money compared subbing it out. And since time is money...
"Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
This guy wanted to be able to weld cool stuff without having to sit there holding a welder for hours at a time, plus he wants to have the welds be of uniform quality. What makes this a "3D printer" is that it uses an X-Y drive rather than an arm with elbow/wrist joints like most robotic welding machines.
dom
But that's the thing. If the environment isn't also controlled, the weld will not be of uniform quality. Welding is an art. You have to pay close attention to ambient conditions, the material being used and the settings on your welder. You need more or less Gas pressure, to adjust the gas mix, higher or lower welding speed, and need to change the voltage. You can also reverse the polarity of the weld depending on if you want the puddle to push or pull based on the direction you're welding. When I welded for a living, storms coming would mean I had to re-setup my machine if I was on a big job. I don't know if it was the barometric pressure, temperature or humidity that did it, but it was definitely something we had to deal with. As soon as I'd lift my helmet to make the change (back then there were no auto-dimming helmets) I'd see everyone else in the shop doing the same thing. Moving to someone elses welder meant re-setting it up to, so personal style must have had an effect as well.
On assembly lines they do just that... they control the environment. It's at a relatively constant temperature, humidity and the welding arm is doing the same exact weld over and over again so they operator can program exactly what it's supposed to do. But it's by no means as simple as feeding in a cad file and pressing "weld" You can do that for sure... crappy welds are good for several metric tonnes of force and can hold on a bumper as well as a good weld... but you're not going to get consistent quality or a "Pretty weld"
Does this mean I can finally download a car?
Yes, there are people who really believe we're at the dawn of Star Trek because a hot glue gun on a stepper motor made a Yoda coffee cup.
Subtractive manufacturing is fairly wasteful of primary material resources.
With that said, I snickered at his mention of how cheap steel would be. I would expect that the biggest expense of his rig isn't going to be the metal... it's going to be Argon. My last refill was $75 for a 45cu/ft tank. He's going to need to figure out how to enclose the entire rig in a sealed (positive pressure vented) box to help conserve gas. Just imagine... an enclosure big enough to do an 8' piece of art... 8^3=512cu/ft. It's a good idea, but there are still some hurdles before this is in the price range of the average Joe.
Which has more power: the hammer, or the anvil?
Cool, sounds like a job for sensors and algorithms.
"Anything you can do I can do better..." sung the old computer...
http://www.masturbateforpeace.com/
Nah, you recycle the waste. It wastes energy, because you're casting more metal than you need only to spend the energy tearing it apart and recycling it, but the metal, minus some oxidation, should recycle fairly easily.
http://www.masturbateforpeace.com/
Video about steel-welding-3D-printer without actually showing it in action. *facepalm*
Assorted stuff I do sometimes: Lemuria.org
Laser sintering is commonly used the term when plastic parts are produced: https://www.additively.com/en/...
I'm not sure what you're saying here. If you mean that the word "sintering" is used mainly when plastics are involved then I'm afraid you're mistaken. It's used when referring to sintering as opposed to melting; melting and sintering are quite different and produce very different finished parts. The question of whether plastics or metals are normally sintered or melted is unrelated.
If God forks the Universe every time you roll a die, he'd better have a damned good memory.
The company that makes the 3D printers SpaceX use call it Direct Metal Laser Sintering. Not selective laser melting.
http://www.eos.info/04ea46b971...
Top of his blog it says TIG.
The top of his blog post says "using ... a TIG machine". TIG welding is not the same as MIG welding: with MIG the wire is one of the electrodes and is fed using a variable speed motor through the torch, with TIG the wire is held separately in one hand in much the same way as it is with brazing and the torch is in the other hand. I think he's used parts of a TIG welding machine because that's what he happened to have. There's no reason I can think of why the same couldn't be accomplished using a MIG welder.
Of course this would be easily settled if the video showed the machine in action or the blog had any sort of description or diagram of how the machine works on either of the two pages.
If God forks the Universe every time you roll a die, he'd better have a damned good memory.
There was a project going on, first at Carnegie Mellon University and then at Stanford's Rapid Prototyping Laboratory, where a very similar but more sophisticated process (Shape Deposition Manufacturing) was investigated to make precise metal parts with full strength (unlike the sintering methods mentioned here and elsewhere). A number of methods were used or tried to melt the metal, including TIG welding, laser fusing and induction heating.
The biggest hurdle to success was the huge internal stress that built up in the process. Remember that one puts layer after layer of molten metal on top of the previous one. The new metal layer solidifies and shrinks, creating lots of compressive on the previous layer. Put down enough of these layers and the part will crack.
And no, doing this process with Invar won't help, because Invar doesn't have this beautiful near zero thermal expansion close to its melting point.
Lets hope the blogger reads what has been published about this process before he commits more effort and resources to his project ...
Seriously, it's like we we've been having a conversation about home-built plastic ultralight aircraft, and then somebody says, "Hey, there's this company out in Seattle that makes aircraft out of metal."
Doing it with molten metal is a new one on me, but people have been laser sintering metal powder for thirty years now, and I bet most of the dollar volume of 3D printers shipped today are of this type. They've been coming down in price too. I have a friend who's a research machinist who has one in his lab, and he tells me that the strength gap between cast metal parts and laser sintered parts has closed significantly over the years.
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