…that has been demonstrated to work in weightlessness.
This could significantly reduce O&M costs at the ISS (and later, at private orbital facilities). It could also revolutionize the pace of research, if someone on the ground could send up the specs for new experiment hardware without having to wait weeks or months for a launch.
“The 3D printer prototype will next engage in environmental testing at NASA’s Marshall Fields division in Huntsville, Ala.”
What is the purpose of this testing? Seems like a long wait – having to wait to fly the thing until next year.
Presumably, they have to ensure that it will be safe to operate (not outgas, etc.) before sending it to ISS.
Hmmm well I assumed these were safety tests….I could see testing it in zero G to be sure the “ink” didn’t scatter all over the place when coming out of the printer…and to see if it in fact printed. Outgassing huh? I suppose the station does not operate at sea level standard. Ok.
Sure seems like a long time before getting it up there and a lot of moving it hither and yon to do the testing.
No, the weightless tests were probably just to see if the thing would work in weightlessness (and thus worth sending into space), not for safety.
I see that as testing both safety and workability.
It may have tested some safety aspects, but there’s a lot more to safety than whether or not it can be operated in weightlessness.
The vomit comet ride was to see that it worked in microgravity. The environmental testing is for safety.
There are a couple of challenges for Filament Deposition-style printers (FDM) in microgravity:
– Outgassing: the printer works by melting the filament inside the extruder, so there WILL be some outgassing. The question is how much and of what gases. And that depends heavily on what material they use and in what thermal regimes. If they want strongest and toughest results, they’ll use ABS, which stinks to high heaven when printed. If they want least environmental impact, they’ll use PLA, which is easy on the nose and eye and produces parts that are strong but somewhat more brittle than ABS. Nylon, Polycarbonate, HIPS and PEI have their own tradeoffs. The environmental testing will help sort that out.
– Layer adhesion: the printer works by depositing one layer at a time on top of each other. The parabolic flights demonstrated that this challenge can be solved – that’s a really important result. I would be interested in hearing more about the materials tested and see the pictures of the results. For example, if they used ABS, were there delamination problems that are common in 1g? What about warping? How was the build platform adhesion?
– Thermal environment: FDM printers require tight control of the thermal environment during the process. There are several sources of heat (extrdurs, linear motion control motors, control electronics), and several areas that need constant steady temperature control (extruder, electronics, frame). Prints may take a long time (it’s not unusual for a large complex print to take 24 hours or longer), so heat buildup is a significant issue in the absense of convection cooling. I’ve been following MiS with great interest since their original announcement, and I haven’t seen any discussion of how they plan to address this issue yet. But I would not be at all surprised if this is a major challenge and requires solutions that are not common in the 1g environment.
– Scaling – Power consumption and weight: most desktop printers today can only produce small parts: .25 – .5 cubic foot is common – and because of this don’t comsume much power and are light. It’s not clear to me, though, that such a small build volume will be worth the effort of all this testing and then hauling the machine up and teaching the astros to maintain what is likely to be a temperamental and finicky machine. When we scaled our machine to 1 cu. ft., we discovered the hard way that the square-cube law really does work against you 🙂 both in terms of power needed to run the machine fast enough to make large format prints practical and in terms of raw weight of structures needed to make the machine robust enough. Our big machine (8 cu. ft. build volume) is even more challenging. I’d love to hear how MiS is addressing these issues as well.
– Impact on the station: an FDM printer has a couple of parts that are moving all over the place (the extruder heads and some parts of the frame) at a fairly good clip (100-200 mm/sec). An extruder might mass 1kg. Is that enough momentum to disturb the micro-g environment for the other users of the station? I don’t know, but I haven’t yet heard anyone do the numbers.
Net-net: there are a few of challenges in this, but none of them look to be insurmountable. And all of them need both analytical and experimental answers – which is exactly what NASA is doing with MiS’s help. Props and best wishes to them both.