How to make an electric arc furnace ?

[my_books]

how to make an electric arc

How to make an electric
arc furnace which can
generate 2000° C ?

 

[heychel]

make carbon arc furnace

You can find more info if you search TIG (tungsten inert gas) soldering techniques

 

[Arropilla]

how to make electric arc furnace

In a very simplistic form, an arc furnace is a electric device which can work with a full short-circuit. In this sense, an Arc Welder (being simplistic again) is a transformer which was constructed to work with its secondary winding in short circuit (through the electric arc).

You can think use an Arc Welder with carbon electrodes to melt conductive metals. Some time ago I read about an article which explain how construct this device. I never found it, but surfing the web I could find this one:

**broken link removed**

Please be carefull, UV radiation due to arc, can make you blind. High currents can burn you and kill you.

LRIOS

 

[liuxiaoganga]

Re: how to make an electric arc

How to make an electric
arc furnace which can
generate 2000° C ?

normally, the steel molten termperature is 1600-1650 ° C ,i guess you are trying to make some other alloy or silicon of which molten termperature is up to 2000° C .

acturally, you don't need to warry about temperature, the temperature in your furnace can reach up to any degree you need. it depends on the material motlen degree.

 

[RetroTechie]

Re: how to make electric arc furnace

Been there, done that (well not the blind/burn/kill part).

Simplest form is a set of carbon electrodes connected to AC mains, with a very low resistance (=high wattage, think water boiler, 2kW heater) in series. When the electrodes touch, the series resistance limits current but the electrode tips & nearby air heat up quickly. When pulled apart slowly, you get a plasma arc in between the electrodes. Extremely bright, white light (including UV!) & temperatures high enough to melt small pieces of glass or even nickel, produce ozone and other bad fumes. At optimum distance 1/2 the power goes into the series resistance, the other 1/2 into the arc. And obviously not safe to touch anywhere (read: using isolated tools to grab / move stuff) due to direct AC mains connection.

When I'd do a repeat these days, I'd use at least isolation transformer, professional electrode material & more precautions / safety gear. Equipment meant for such uses is even better...

Please be carefull, UV radiation due to arc, can make you blind. High currents can burn you and kill you.

You forgot ozone, nitrogen oxides, liquid metals, open fire, 1000+ °C sparks & objects that decide to fall apart @ such temperatures... :razz::shock:
Gasses & UV can do severe damage you won't notice until later.

In other words: think before you act, and use all protection available!

 

[BradtheRad]

In my younger days I read about how an electric arc furnace is made using carbon rods.

So I extracted two carbon rods from D batteries, and tried to make an arc by connecting them to house voltage. As soon as I touched them together, immediately it caused a fuse to blow.

I tried to touch them together very quickly, then separate them a tiny bit. I could not get it to work.

I tried putting a bright light bulb inline. It reduced the voltage between the carbon rods so that I could not get an arc.

I forget how high a wattage bulb I tried. In any case, 120V is only able to spark across a small gap. There would need to be a plasma generated around the electrodes from the start, to keep an arc going.

So I think it will need 230 V and a high current load inline, in order to succeed at making an arc.

 

[RetroTechie]

Hehe, used those too, and some pulled from those square 6V batteries. Also tried pencil leads but those tended to explode along their length... :shock: Maybe plain iron wire would be easier; melting isn't much of a problem if you start out with decent length electrodes.

I forget how high a wattage bulb I tried. In any case, 120V is only able to spark across a small gap. There would need to be a plasma generated around the electrodes from the start, to keep an arc going.

So I think it will need 230 V and a high current load inline, in order to succeed at making an arc.

At the moment the electrodes touch, the current flows through a very small surface area so that heats up fast. This in turn heats up the air around that point. When hot enough, that air ionizes & thus becomes conductive such that a much lower voltage is enough to sustain current through the arc. As electrode distance increases, the required voltage goes up but (with a series resistance setup) a larger % of total power goes into the arc. At the same time losses increase due to larger size/volume of the arc & radiated light. The sustained arc you get is basically the balance between these 'forces'.

The point is to have a sustained current flow, and enough electric power available to put into the arc (like at least some hundreds of Watt continuous). Read: as series resistance, pick an ohmic load with wattage close to what your fuses will bear, and move electrode tips carefully. Probably there's methods with better efficiency (inductive load in series like with fluorescent lighting?), perhaps there's a practical minimum voltage for this kind of arcing. :?:

At the time I had 220V / 50Hz AC and several centimeter wide sustained arcs, so I'd be very surprised if one couldn't do the same starting with 120V. Anyone got a set of 10 car batteries to spare? :evil:;-)

 

[BradtheRad]

At the time I had 220V / 50Hz AC and several centimeter wide sustained arcs, so I'd be very surprised if one couldn't do the same starting with 120V. Anyone got a set of 10 car batteries to spare? :evil:;-)

Several centimeters... that is a large arc.

I would have tried harder if I had known it was possible to get an arc with house current.

It's just as well I didn't succeed. Being young I didn't realize UV light is bad for the eyes.

Years later I would run an arc welder. The helmet had a filter glass so dark that the only things I could see through it were the sun, and an arc.

At least a couple times I got a headache after doing a big job. I sometimes had to weld where I didn't have good light, so I would lift my helmet to let me see exactly where I was striking an arc, then I would lower the helmet to weld.

One day I read that getting a headache after welding means I let my eyes be exposed to too much UV light. I would have sworn I only exposed my eyes to the arc for about two seconds total.

So I learned to close my eyes just as I struck the arc. I certainly did not want to risk burning a hole in my retina.