Researchers demonstrate rapid 3D printing with liquid metal | Hacker News Reader

Researchers demonstrate rapid 3D printing with liquid metal

news.mit.edu

137 pointsclouddrover42 comments

This is exciting but incredibly niche atm. The parts it produces have to be milled and machined afterwards which in some cases could increase the manufacturing time overall. I do like their approach of keeping it hot and printing inside the sand. Much like casting. The nozzle however pushes sand all over the place and is probably pushing it into the path, causing the poorer quality prints. I spent a couple years as a young adult in a metal part manufacturing plant while going to school.

It’s exciting though because I believe we’ll have a time, not too far from now, where a design can be fed to a molten printer to print a base part, transferred to cnc mill for final refining, and then polished and painted for shipping. It won’t cost $10M to create a fabrication facility. It won’t require 25 years of industrial mechanics to build your “plant”. Just get “Bubba the Boiler” metal 3D printer, “Michael the mill” CNC miller, and the cast and crew of smaller tools to buff, polish, powder coat.

I’ll stick to wood and plastic for now. More my “level”.

It's not actually sand, it's glass balls.

Fancy sand!

Same thing

Nope, just google for "sand microscope".

Dude, when you cast molten metal into sand, you create glass micro balls. They are just starting from there. Sand is glass, heated to molten temperature and fused into a crystalline structure.

What is commonly understood as sand, has not much to do with little glass balls, even though here we have glass balls. A very special type of sand you can say, but not common "sand". But I feel no need to go more into pedantery here ... if this is sand to you, then I am fine with it.

It doesn't cost $10M in equipment costs to create a basic fabrication facility for short-run metal parts today, right? You pay for land, permitting & compliance, construction, etc. Machinery to cut "consumer-sized" parts out of metal stock, or to stamp sheet metal, usually costs six figures or so.

Lost wax casting, which is done with CNC-machined molds, isn't a capital-intensive process either.

An old but servicable lathe and mill can be had cheap on craigslist anytime. $5000 with some tooling. $10000 if you want cnc and digital readouts, with plenty leftover for more tooling. new imports can be had for similar prices - there is debate about which is better (both are compromises somewhere, new of what the craigslist stuff was new will cost you $100,000 or more).

or you can send the print to any machinist to manufacture for you. There are many around, but often they won't talk to you for small runs. (but someone will)

This is reminding me of a YouTube channel I watch, Cutting Edge Engineering in Australia. It's a shop that does machining and welding in support of things like bulldozers and other construction and mining equipment.

https://www.youtube.com/@CuttingEdgeEngineering

There's something hypnotic watching someone fabricate precision objects.

Wow, that’s an amazing channel! I expected to see big parts on big turning machines from your intro, but somehow they were even bigger and better than anticipated in the best possible way.

in equipment costs you are correct.

> This is exciting but incredibly niche atm.

However, the "niche" is a non-trivial one--injection molds.

Machines already exist which deposit metal and also have a 3-axis CNC head that can then polish up the surface of that metal in the same envelope. This lets you directly print 3D molds with conformal cooling.

So, it doesn't matter if your machine is "slow" as long as it's faster than your alternatives for producing an injection mold.

I love that I can always count on the internet to tell me why cool new things are dumb and not useful.

Nice. But Cranktown did this 2 years ago, in his garage.

https://www.youtube.com/watch?v=L7sv3HkDyok

That guy really needs a lot more followers.

That looks like a super different process for entirely different applications.

I saw a video about this a few days ago, one thing that’s not addressed is what aluminum alloys this works best with. Some alloys aren’t suitable for casting. And separately you need to flux the molten solution to separate out oxides and make sure there’s no voids or inclusions in the metal object.

That said, this is brilliant and could easily have huge impact in non structural applications or prototyping.

Would this device actually work out to be cheaper than a cnc machine milling out a solid alloy block?

For skletonized stuff, the reduced waste in raw materials might make it compelling. Those large solid blocks of quality material ain’t cheap.

I imagine the turnings are recycled

You can't mill internal cavities and other structures that are possible by additive manufacturing.

This isn’t really additive manufacturing though, it’s more like cnc casting if I understand correctly.

Recently on twitter an e/acc-aligned person posted some techno-optimist propaganda to the effect of “if primitive societies could see our existing technology, rockets, supercomputers, semiconductor fabs etc, they would see us as gods rather than human beings” (paraphrasing).

Someone else leapt in to provide a number of very interesting accounts in which isolated tribes e.g. Inuit, aborigine, etc had actually been taken to marvel at advanced western technology - cars, skyscrapers etc. These were obviously cherry-picked accounts but it was nonetheless thought-provoking and very funny to me to read about these guys being deeply unimpressed with our shit. “You mean you have to feed this mechanical horse with dinosaur bones and you have to work all day to pay for the dinosaur bones? My horse feeds itself” type of stuff.

I love an enthusiastic MIT student project as much as the next man but I think it’s really nice to sometimes view stuff like this through the lens of an ancient master craftsman. I accept that some open-minded farrier from the Middle ages, when shown this contraption, might be impressed, but I also think a decent fraction might be shaking their heads in dismay :)

It seems like there are still a lot of challenges from the physics of printing liquid aluminum. To me this seems like it overcomplicated the task because they chose to print the aluminum, rather than just printing a form that can hold molten aluminum as a traditional casting might. Maybe that is already done though, this is academic work after all and not necessarily done to seek optimal solutions but to scope out future challenges.

There are useful shapes you cannot form through casting or subtractive manufacturing, such as shapes with complex cooling channels inside them or weight reducing voids.

Digital sand casting is a thing yes: https://www.youtube.com/watch?v=_ClnmiggRPU

Printing a sand mold and cores is quite a bit slower than this new MIT project through, so the OP may have a useful niche.

I'm a 3D printing enthusiast. I find this to be incredibly interesting.

There was an interesting product at CES that used a gelatinous bed into which resin is injected and cured making it possible to print objects without supports.

Being able to do this with metal opens up a ton of future manufacturing options. It's not quite the same process and it's quite early, but with refinement this could be a very interesting future option for quickly building entire objects in minutes that would normally take hours.

I'm waiting for the time when 3D-printer can print a 3D-printer.

Will the 3D printer manufacturers cry about "piracy" then?

Very clever! But it looks like that this is more like making grooves in glass sand and pouring molten aluminum in the groves than traditional 3D printing! I’d be curious if the characteristics of these parts are akin to cast parts. Also, my understanding is that this is more of a 2.5 D process than a 3D process. I’m. I’m curious as to how this process may scale to a 3 D process! Still cool!

Sciaky is a company in Chicago who's been doing far more impressive work for decades now.[1] They've got a few different additive metal technologies to choose from.

It would be interesting to see about rapid production of one-off molds for sand casting, maybe printing wax and filling with sand, using 3d printing techniques?

[1] https://www.sciaky.com/

Sciaky goes higher quality at slower speed. The tech in the OP is not impressive because of the finished product, but just because of how quickly it prints.

I don't know a ton about metal internal structures but I would assume that the properties of the printed product will be lesser than if it was made from extrusion or some other process? I think there's something about crystalline structure and the speed of the transition from liquid to solid. Would love to know someone else's informed guess on this.

Probably yes, forging is often best but I suspect this is similar to casting although there might be more voids. For non-critical structural applications it might work. You can also heat treat certain aluminum alloys after casting/welding to improve properties.

Yes, there are a wide variety of what amount to recipe books for different aluminum alloys along with their post treatment temperature profiles. Usually this includes details such as various impurity concentrations (more for steels), what temperature and time it is held at for each step of treatment, and processes like work hardening would be in there. There may be barriers to work hardening here but the heat treatment process seems like it should be similar to other casting processes.

At least I'd think so, sand and glass beads aren't terribly different.

I would expect that temperature and nozzle clogging would be where you'd see issues, with speed and probably small solid chunks causing bursts in flow rate since it's gravity fed. I'm sure they've thought of it... I'd expect it to be better than something built up layer by layer though, there's no messy attaching aluminum oxide layers to one another and figuring out a clean way to do it and then afterwards heat treat it properly all over again.

kind of remind me of a pistol slide at 0:27... but yeah this isnt 3d printing, it is molding... and I haven't watch the whole video but I don't think they show you how they make the mold.

They insert a probe deeply into glass beads to deliver hot metal liquid as the probe moves along the programmed path.

That part that looks like molding is for to show how the metal liquid will cool down inside the such beads.

(You should have watched the whole video)

at first I thought it was a tool designed to 3D print casting molds... it isn't, it's just a nozzle creating a casting profile by direct injection underneath what amounts to fine sand.

Good news, by improving system

So like sand-casting, only worse.

Title should read “molten metal”. Liquid metals are a thing, and the title is ambiguous. https://en.m.wikipedia.org/wiki/Liquid_metal

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