Flying Balls of Molten Aluminum!

We’re replacing “holy moley” in our vocabulary. Levitating globs of molten aluminum are that much more amazing. It’s not that we couldn’t believe it would work — we understand the physics after the fact. It’s just that we never would have thought to build an induction forge that can simultaneously melt and levitate a chunk of aluminum. (Video embedded below.)

[imsmoother] has had plans for 3 kW and 10 kW induction heaters online since at least 2011, and we’re wondering how we haven’t covered it before. Anyway, in the video, he’s using the smaller of the two to melt a chunk of aluminum.

The trick with aluminum is that although it’s non-magnetic, it’s fairly easy to induce eddy currents in it. Basically, the pulsing current in the coils creates a changing magnetic field that induces current loops in the aluminum, which act like electromagnets, creating their own opposing magnetic field. When these two are strong enough, they can suspend a block (and later, blob) of aluminum in the air.

We have no idea if this has any practical applications — it’s easy enough to melt aluminum in a crucible and this floating induction process is limited by the weight of the aluminum that needs to be suspended. But still, it’s an awesome demo. (See also this classic video while on the subject of aluminum, magnets, and eddy currents.)

Forging seems to be in the Zeitgeist at the moment. We just ran an article on direct-metal 3D printing, and you don’t have to go back too far to find projects like the Reactor Forge, a 1000 W induction solder pot, or this Kentucky-Fried furnace. But if induction is not your cup of tea, you can always melt aluminum in your microwave.

Thanks [Julia Longtin] for the unintentional tip, via HacDC‘s mailing list!

47 thoughts on “Flying Balls of Molten Aluminum!

        1. Or perhaps just leave it in the heater for quite a while and wait for the vapor (at a good distance). People often forget that metals will boil/vaporize (though for aluminum it’s over 2400C).

      1. I am surprised that he didn’t get a nice visit from the tinsel fairy. I was always told never to let molten metal land on cement because of the moisture left in the stuff. I can only imagine the fireworks that could have happened had the aluminum landed on any of those oil splashes.

        1. I did not notice that the first time. Isn’t that three strikes for him?
          Loose extension cords under ball of floating molten aluminum.
          Spilled oil under ball of floating molten aluminum.
          Ball of floating molten aluminum…

      1. Wouldn’t it depend on the speed you launched the blob? If you could launch the blob at around at around the speed of a bullet it would still do a hell of a lot more damage than a small chunk of lead.

  1. Wow! Would it be possible after it has completely melted to lower the current enough that it solidifies onto a deformed blob? Or is the energy required to keep it against gravity too much to allow the blob to cool down?

    1. Obviously the levitating force does not require any heat to be created at all.
      It’s not like all the magnetically levitated stuff like maglev trains are all hundred of degrees hot and in a liquid state.

        1. Aluminium will respond as long as the magnetic field keeps changing, so it makes little difference in terms of the heat part.
          Also, isn’t it cool and levitating at the start of the video?

      1. Specifically, can HIS setup levitate the aluminum after it is molten while the blob cools down. We don’t know if levitating at its lowest threshold would allow it to solidify.
        Unless I missed an explanation in the video.

  2. Please make this into a lamp.
    I wonder if it could be scaled down to a ‘reasonable’ size and temperature. It would be the world’s coolest (haha, not literally) red-purple night-light. (But no way in hell am I going to sleep with that monster glowing!)

    1. Manually focused because of IR interference and excessive brightness wouldn’t allow auto focus possibly.
      Unless you mean low quality picture? Looks good to me.
      (Except terrible focus.)
      Then again, maybe the EMF is screwing with it.

          1. Well you did get a laugh, but for another reason lol.
            I would like a warning that reads ‘link’ or ’embedded image or video’. HaD has a suggestion box. I might throw something at it.

      1. they don’t work with aluminum or copper. steel (and iron), and graphite are about the only things you can heat up directly. titanium works slightly. I have the big and small unit.

  3. I think this comes under the bracket of, “any significantly advanced technology, can be seen as magic” :D
    I quite enjoy watching things like this.
    I need to build a big one at some point :D

  4. The real use of this sort of thing is in high purity metal melting – gold, silver, platinum. You can melt a blob of it and know its not going to pick up contaminants from the vessel walls. Generally not for jewelry but for precision electronics!

    1. I was wondering if the molten blob of aluminum could be used to grow large corundum crystals. Blow oxygen over the blob over an extended time frame and sufficient Aluminum oxides should develop. If the temperature:time profile is right, the oxides should dissolve into the blob and start crystallizing after a certain density threshold is met.

  5. “We have no idea if this has any practical applications — it’s easy enough to melt aluminum in a crucible and this floating induction process is limited by the weight of the aluminum that needs to be suspended.”

    I thought of a good one – it’s a safety improvement! No, really (although obviously not if you treat it the way it’s used in the video). You can simply put your induction heater over your mold, levitate the aluminum while it melts, then shut off the field and have it drop into the mold. No walking around with a crucible of white-hot metal on the end of a pair of tongs or having to make your entire furnace tip over and pour the metal out. Removing the requirement to move the molten metal horizontally means that the metal can only spill in one place, and that’s right over the mold.

    1. Or just use an Ardunio. Haha.

      I like that. Would be interesting to try but there could be ‘splash issues’. But that could be solved with tubes.

      I want to make a mini version, over a simple sand mold.

    2. How about a continuous-feed induction forge? Long coil, you feed it wire or rod from the top, and it’s liquid drizzling in a continuous stream into the mold.

  6. This process have been studied by in the URSS back in the 196x. A Swiss aluminium company (Alusuisse at that time) buy the license to continue the study in the end 197x. There finally get a working production of aluminium ingot (about 6m length of 2m x 0.6m section if I remember correctly) machine called Low Cost Automatic Casting. I know that several of them was sold in USA in the 199x. It was insanely complex machine from the electronic point of view with gigantic current converter, early LED matrix screen to sustain the magnetic field, and high speed computer to keep about half a tone of liquid aluminium with the required section shape on top of the already solidified part that slowly go down into a water pool. The advantage of the process was a more homogeneous ingot, especially near the surfaces, compared to traditional casting, an important parameter for the quality for the next metallurgic processes like lamination or extrusion. The disadvantage was that if something go wrong (like power cut) you have half a ton of liquid aluminium that fall into a water pool and this usually make a dangerous mix that can spread liquid metal several meters apart. The problem exists also into the traditional casting process, but the liquid aluminium don’t fall all together at the same time, limiting the danger.

      1. I am not aware of any video of the development machine I have witness, but it’s not so spectacular to see because the surrounding coils take a lot of space, hiding the liquid part of the aluminium. If I remember correctly the distance between the liquid aluminium and the coils was a few centimeters only. The coils was water cooled from inside. In the building where the development machine was, when the machine was in test, only a couple of peoples where authorized to stay inside fully covered by thermal protection cloths.

        Internet was not a subject at that time so it’s difficult to find something online. I just found this:
        http://www.google.com.na/patents/EP0015870A1?cl=en (same process but for continuous casting)
        https://infoscience.epfl.ch/record/31987/files/EPFL_TH1509.pdf
        The last document have a lot of details about the process but unfortunately no photo. It say that the ingot section was 1.86m X 0.51m (just a bit less than was I remembered) so you can imagine the scale of the machine. The part above the surface was not big, maybe about 1 meter only. The rest are essentially the pool under the surface. There was a gigantic natural gas oven aside of the casting machine to hold and supply the liquid aluminum. The current converter was several meters away and was the size of a small truck. Many monitoring devices was connected to a VAX machine that communicate with a 1Mbps coaxial ethernet. This was the first ethernet network I have see in my life :-)

    1. I’m going to the library. It looks like a good read! It is A.C.C after all.
      I haven’t read a novel in ages, this may be it. That or From the Earth to the Moon.

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