electric arc furnace
Moderator: Harold_V
electric arc furnace
hello,first i must say this is a great sight.I've enjoyed going through some of the post and have learned quite a bit.Now to my question.how hard would it be to build a small carbon arc furnace to melt small batches(10lbs. or so)?it seems to me i've read insome old issues of popular mechanics or something and it didn't look that hard,but theres always those little things you never think about that messes you up!thanks for any replies and knowledge.
-
steamin10
- Posts: 6712
- Joined: Sun Jun 08, 2003 11:52 pm
- Location: NW Indiana. Close to Lake Michigan S. tip
furnace
You didn't say the material, but most everyone that does hobby casting does a crucible furnace, either bought or homebuilt. Go to one of the several foundry boards and read on.
Then tackle your local library.
Look for books written by C. Ammen
He has written extensively for the small shop, and is the touchstone of the hobby , in my opinion.
Then tackle your local library.
Look for books written by C. Ammen
He has written extensively for the small shop, and is the touchstone of the hobby , in my opinion.
steamin 10,i appreciate the response.I do have many of C.W. AMMENs books as well as many other books on casting.I've even built a LIL BERTHA furnace for all my alluminum castings.What i'm looking for now is suggestions or ideas about a furnace for cast iron or steel.I really dont want to have to go the Cupula way as its really messing and tons of smoke.I know alot of mini mills are now running a electric arc furnace and thought it might be a good way to go.I just need some kind of idea as to what voltage or amperage i would need and anything else someone might come up with.Thanks.
-
David_toledo
- Posts: 147
- Joined: Sat Jan 04, 2003 11:57 am
- Location: Toledo,Oh
I now work at a steel foundry and we have two ten ton arc furnaces. They are low voltage, but 20,000 amps on three phases. I beleive our graphite electrodes are 6 inch. The transformer for one furnace fills a whole room. I just cant see this being more efficient than a blast furnace.
It takes a little over an hour to bring each heat to pouring temp. When it pours from the furnace I beleive it is around 3000 degrees and cools slightly before pouring in to the molds.
Oso
It takes a little over an hour to bring each heat to pouring temp. When it pours from the furnace I beleive it is around 3000 degrees and cools slightly before pouring in to the molds.
Oso
-
steamin10
- Posts: 6712
- Joined: Sun Jun 08, 2003 11:52 pm
- Location: NW Indiana. Close to Lake Michigan S. tip
furnace
Iron and steel require a lot of heat, and that means raw heat input. It takes equipment that is rapidly outside the abiliity of a home Lab or garage shop.
Iron can be done in a crucible furnace in a reasonable , but small quantity. Steel temperatures can be attained but the chemistry is complex and beyond the scope of a home shop. changing conditions make for a tough call on additions to make the chemistry you want, and then only testing will show what was made. A very difficult deal in micro, and tough in the real steel industry. Iron However is not that hard, as it is very happy to settle into several natural forms, that are easily controlled.
I speak from 25 yrs experience around steel mills and a foundry. I was a millwright, and learned many ptifalls of the process.
I have three crucible furnaces, and have not done iron, because of the wear on equipment at such required high temperatures. I dont think you really want to go there. The cost for such items made will be very high, just in terms of equipment maintenance.
Having said that , there are lab sized kilns of the electric convection/radiant design that might get you close to what you want. I doubt the average person can afford one.
Iron can be done in a crucible furnace in a reasonable , but small quantity. Steel temperatures can be attained but the chemistry is complex and beyond the scope of a home shop. changing conditions make for a tough call on additions to make the chemistry you want, and then only testing will show what was made. A very difficult deal in micro, and tough in the real steel industry. Iron However is not that hard, as it is very happy to settle into several natural forms, that are easily controlled.
I speak from 25 yrs experience around steel mills and a foundry. I was a millwright, and learned many ptifalls of the process.
I have three crucible furnaces, and have not done iron, because of the wear on equipment at such required high temperatures. I dont think you really want to go there. The cost for such items made will be very high, just in terms of equipment maintenance.
Having said that , there are lab sized kilns of the electric convection/radiant design that might get you close to what you want. I doubt the average person can afford one.
-
steamin10
- Posts: 6712
- Joined: Sun Jun 08, 2003 11:52 pm
- Location: NW Indiana. Close to Lake Michigan S. tip
furnaces
As an aside, there is good economics to an electric arc furnace on a number of levels.
One, is that you can go from a cold start with cold scrap to finished melt in a short time period. With a cold shutdown right after without disasterous effects or holding costs. Another advantage is that changes of chemistry can be accomplished from heat to heat making low carbon to high carbon and alloy steel changes at will. Small batch furnaces are the core of exotic metal production for this reason, making tool steels of exotic forms without the need for holding lots of inventory. It all points to an economy of operation overall, where the power cost is high in relation to other items, but wins out as a running cost with low equipment values over massive installations that would require acres of land and huge built facilities to handle the mass volumes of materials to make efficient operation possible. Many mini-mills have learned to consume scrap and produce batch carbon steels at competitive prices to larger and more efficient integrated mills. This shift in abillity has been the cause of the steel industry shaking out aging operations. The economics are not there to rebuild the dinasaurs that used to be the core of the industry. As modern technology has dealt the steel industry a dictum of high standards and narrow windows of technology for specific application, or materials tailored for a specific job, just producing general steels has not helped the larger makers, as more flexible operations have taken over those markets, leaving larger steel producers on the ropes.
Thank you , Mister Know-it-all.
I'll be quiet now
One, is that you can go from a cold start with cold scrap to finished melt in a short time period. With a cold shutdown right after without disasterous effects or holding costs. Another advantage is that changes of chemistry can be accomplished from heat to heat making low carbon to high carbon and alloy steel changes at will. Small batch furnaces are the core of exotic metal production for this reason, making tool steels of exotic forms without the need for holding lots of inventory. It all points to an economy of operation overall, where the power cost is high in relation to other items, but wins out as a running cost with low equipment values over massive installations that would require acres of land and huge built facilities to handle the mass volumes of materials to make efficient operation possible. Many mini-mills have learned to consume scrap and produce batch carbon steels at competitive prices to larger and more efficient integrated mills. This shift in abillity has been the cause of the steel industry shaking out aging operations. The economics are not there to rebuild the dinasaurs that used to be the core of the industry. As modern technology has dealt the steel industry a dictum of high standards and narrow windows of technology for specific application, or materials tailored for a specific job, just producing general steels has not helped the larger makers, as more flexible operations have taken over those markets, leaving larger steel producers on the ropes.
Thank you , Mister Know-it-all.
I'll be quiet now
-
Doug_Edwards
- Posts: 612
- Joined: Thu Apr 10, 2003 8:06 pm
- Location: No. Idaho
- Contact:
Re: electric arc furnace
In the 20's or 30's there used to be a line of arc furnaces, the smallest of which had a 10 lb pour. I doubt these would come near to passing Osha today, and suspect that except for very small outfits are long out of use and scrapped. I think the small ones were not uncommon in small investment foundries years ago, but I think they have been replaced by the induction furnaces. The down side of the arc furnace is that they will add some carbon to the melt from the electrodes, but the induction furnace will not do that. That being said, I should think that you could rig up something using a large welder (with high duty cycle) for your power supply. I seem to remember the voltage being pretty low on arc furnaces of any size. Hope that is of some help.w b wrote:hello,first i must say this is a great sight.I've enjoyed going through some of the post and have learned quite a bit.Now to my question.how hard would it be to build a small carbon arc furnace to melt small batches(10lbs. or so)?it seems to me i've read insome old issues of popular mechanics or something and it didn't look that hard,but theres always those little things you never think about that messes you up!thanks for any replies and knowledge.
Steel casting is not for the faint hearted, but is not out of the reach of the determined. I have a customer that was not happy with the small steel castings they received from their foundies, installed their own induction furnace, and are now doing all the foundry work in house. No one had any foundry experience in that business. For the hobbiest it is harder to foot the bill to get to the point to be able to melt metal. I have long been very interested in steel casting, but on checking the cost, even for a limited commercial venture, I am money far ahead by having foundries cast my parts rather than do them myself. Fwiw.
Doug