Reverse Polarity Magnets?

[Joe Jones]

I am curious about something. Is there any way to build a an electromagnet that will ATTRACT metal dust, but then RELEASE that metal dust when the polarity is reversed? Electronics escape me. I am a mechanical guy. Once a project involves circuit boards, etc., I am lost.

Joe

[acourtjester]

If you are using an electromagnet it only works when poser is applied. turn it off and you can sweep it clean. Many guys use one on a drill press to hold metal whole drilling, switch off when done. build on your self.

[Joe Jones]

I am playing with a way to use wide belts to capture drops and dust, and deposit them into hoppers at the end of the table. I have two designs. The first one is more complicated. Two concentric belts. The outer belt is longer than the inner belt.

The inner belt is a bank of electromagnets that turn ON at the top of the horizontal oval, and OFF at the bottom. This gives the outer belt a magnetic quality to capture drops and metal dust. This would catch and transport drops and plasma dust to the end of the table. The drops would then fall off of the shielding outer belt and into a tray as it circles beneath the table lower than the magnet belt beneath it, which would pull the drops and dust away from the magnetic sub base.

The dust would be brushed off and fall into a separate hopper, or onto the floor for later collection. The belts would return clean and sandwiched together at the other end of the table. It would work sort of like a lamination machine.

The second design does not use magnets at all. It is simply a steel belt that runs beneath the grates, like the belts you see in pizza ovens. The drops would fall onto the belt which would transport the drops into a tray at the end of the table for easy disposal into an oil drum or whatever. The smoke and dust would simply blow through the belt to the floor as normal, and the air duct system would remove the smoke and dust to the outside of the building.

I have one "Version 2" about 20% constructed at the moment, but I am shifting gears, and looking at a long, wide stainless steel belt instead. They are not cheap by any means, but they will certainly do the job. I created this first attempt by linking 4"x9" stainless baking racks together with hog rings. Believe it or not, it works! I am making one for my 5x10 table, so it is quite large at nearly 25 feet in length x 60" wide. I am also considering making one out of a simple chain link fencing material, with small than normal links.

Fun times!

Joe

[adbuch]

[Joe Jones]

I suppose it would work to turn a magnet ON and OFF. I was looking for a way to physically repel the metal from the magnet, but I guess that would not work by reversing the polarity, because it would still be an electromagnet. I guess the ON/OFF option is the way to go.

In a perfect world I could create ceramic tiles with electromagnets inside of them. The belt would be a steel mesh that holds the tiles edge to edge on a flat surface. On the top of the belt cycle, the tile "bed" would be edge to edge, and the magnets would be turned ON. The metal would drop to the tile platform, along with the metal dust, etc. As the belt wrapped around one end, the magnets would be turned off. The drops would fall into a tray, and a brush would remove most of the metal dust, returning clean tiles to the other end to circle back to the top again.

All just theory, at this point, but it might be worth the experiment.

Joe

[robertspark]

magswith on top, and mag switch on bottom.... or electo magnet on top and bottom and turn one off and the other on

[adbuch]

robertspark - very interesting video!
David

[Joe Jones]

I played with electromagnets when I was a kid. I know that you can energize them by turning the power off. I set my bedroom on fire, learning that lesson

I was more interested in whether the magnet's polarity could be reversed, or more accurately, if a magnet that attracts metal in one polarity could REPEL the metal in the opposite polarity. I see that this cannot be so, unless the metal itself is also magnetized to provide an opposing force. Otherwise the magnet will still attract the metal, but from the South pole rather than the North pole.

I cannot use a rubber conveyor belt beneath a plasma torch for obvious reasons. If I use a metal belt, the metal itself will become magnetic at some point, from the electromagnet being turned on and off. It will hold onto the plasma dust I am trying to remove, and become a fuzzy mat of mess. Of course if the belt is aluminum, or copper, or some other non-ferrous screen metal, then I guess that would not be a problem.

I am abandoning the magnet idea for now, and looking at fine mesh stainless steel chain link fencing material. "Marine fencing" is what I am finding. Stainless steel fine mesh for boats and docks, etc. The mesh would catch the drops and deposit them into a tray at the end of the table, and the smoke and dust would pass through the belt and be removed via traditional exhaust fans or by some other means.

I am now wondering if there is some liquid I could wash the belt through prior to passing it beneath the cutting grate, that would prevent the dross and crud from sticking to the chain link material. It would have to be some non-flammable liquid that would not drip from the belt, but only carry the small particles to a wash basin that would return a relatively CLEAN belt for repeated service per revolution. I know about "anti-spatter" spray. I wonder if that would work on a large scale.

This is the general concept. Drops would fall off and into a tray at below grate level. Dross and dust would be cleaned off in some other way, before the belt returns to pass beneath the grates again.

Joe

[Joe Jones]

If only I could set this up so the plasma torch does not damage the screen!

Joe

[PlasmaDon]

Magnet on a Blanchard grinder does what your asking.
Neutrofiner was one, here is another:
https://www.walkermagnet.com/products/w ... k-control/

[Joe Jones]

Magnet on a Blanchard grinder does what your asking.
Neutrofiner was one, here is another:
https://www.walkermagnet.com/products/w ... k-control/

Thank you.

Joe

[Francisco]

When you turn the magnet`s DC supply off, a relatively weak magnetic field remains. If you briefly supply AC, the mild steel core (and, in your application, the plasma dust) will be demagnetized. Gravity will finish the job.

[Joe Jones]

When you turn the magnet`s DC supply off, a relatively weak magnetic field remains. If you briefly supply AC, the mild steel core (and, in your application, the plasma dust) will be demagnetized. Gravity will finish the job.

Thank you! That is the answer I was seeking. I can make an electromagnet, and I can turn it ON and OFF. But I want the plasma dust to completely fall off of the magnets, rather than become a residual layer of fuzzy dust, as the steel cores themselves become magnetized over time. That is why I thought I could reverse the polarity, to neutralize the residual magnetic characteristics, but you say a shot of AC power does the trick?

Now ... HOW to make a conveyor belt that consists of a bank of electromagnets, tough enough to repeatedly pass four inches beneath a plasma torch, and take the physical abuse of sharp, falling "drops," and still deposit dust into one tray at the end of the table, while depositing the drops into another tray for retrieval ... I'd better order a big box of Unobtanium!

Joe

[PlasmaDon]

Eriez Magnetics.......