Electric arc- aluminium melting

[kadora]

Hello all
Guys does somebody of you use electric arc aluminium melting?

regards Kadora.

 

[moya034]

I haven't practiced enough to give you much advice about technique, but I will tell you if you want to arc weld aluminum, you will need a TIG machine capable of doing AC. HF start will make for less tungsten contamination.

DC electrode negative creates more heat in the work piece, but electrode positive breaks up the surface oxides. So in aluminum welding we have to break up the oxides with electrode positive, however that will melt the tungsten, thus why we use AC, to get the best of both worlds.

Also, you will need a stainless steel wire brush that has not been contaminated by use on any other metal.

Oh, also aluminum has great heat conductivity and thus acts like a heat sink, which is why you need more amps vs welding steel of the same size.

Edit... I should add that the do make electrodes for doing stick welding using electrode positive DC. They work, but are not popular, and are better suited for large work pieces.

Edit 2... Just realized you are probably talking about casting and not welding... LOL.

 

[moya034]

As far as a furnace goes, yeah, sure it's done. Electric arc isn't typically very practical for most home foundries, where charcoal, propane, or oil/diesel is usually preffered.


If you already have the power supply, then I don't see why a furnace and some graphite electrodes would not work.

 

[Lakc]

While the idea of a homebuilt arc furnace is intriguing, I cant see bothering to go through all that for aluminum. AL melts easily enough with charcoal or propane.

I dont know of anyone who has built a home arc furnace foundry of more then a couple of ounces capacity, but it wouldn't surprise me to hear of one.

 

[moya034]

I just found this thread you had posted on the same topic. I'm assuming you are trying to ask a different question, but I'm not sure what it is.

 

[kadora]

Hallo friends

moya034 yes i have two threads maybe the same but from my point of view
threads are different.
I want to melt aluminium to be able to cast my own engine parts.
I want to use electricity to melt aluminium i can not use open fire.
I have found this arc method on internet so i was pretty curious
if somebody uses this arc technique because this method probably needs only welding machine to melt a metal.
Thank you guys

 

[///]

... i can not use open fire.

It may be worth checking your city's definition of an open fire.
As I mentioned in your other thread, a propane or oil fueled furnace is a contained fire, not an open fire.

 

[Lakc]

A welding machine will melt very small quantities at a time, probably limited to the machines duty cycle. Arc melting furnaces are three phase power and from what I can gather, are usually using 480v straight off the pole.
As Simon says, there are plenty of propane home foundry designs that are sufficiently contained to the point that nobody would consider it "open flame". Since propane is ashless, nobody would know its there to ask in the first place.

 

[bhowden]

I have used charcoal, propane and electricity. I found the charcoal and propane a bit noisy and expensive and created enough smell / smoke that I had to be careful when I was doing it (wife out and neighbors away, house windows closed, no laundry out!). For electricity, I bought a used top loading potters kiln for $100 and added a PID controller out of Hong Kong. With the thermocouple, solid state relays etc that added about $120. I preheat the crucible so the molten aluminum is exposed to air for a shorter period of time. I turn off the power when I have the kiln open so there is no danger of electric shock. I have only used it a couple of times but so far it seems to work fine and can be done in the garage if it is raining. If I am inside, I put down a 4' X 4' sheet of 1/8" steel and an inch or so of sand to make sure molten aluminum never hits concrete. I think the kiln route is far easier, cheaper and quieter than getting electric arc to work properly would be.

Brian