Step 7: Smelting and Casting Aluminum

Okay lets get started with the smelt. Leave the blower turned off until the coals are established and have some grey ash on the surface. Turning the blower on prematurely will blow the fire out however once grey ash appears on several bricks the blower will greatly enhance the process from then on.

If you use on those charcoal starter devices with newspaper or whatever get your coals started. Otherwise remove the crucible and spray on a good dose of starter fluid. No need to go crazy, it won't help. Use the same sort of amount you would use the start the charcoal in your grill.

Light the charcoal and, holding the crucible the extended rod ends, place the crucible back into the furnace. **CAREFULLY** drop in additional briquets up to about the level of the crucible rod. Don't over pack, you can always drop in more briquets later.

Take the last two bricks and place them **CAREFLLY** on top of the furnace to form a chimney. They should be placed so that the center of the furnace forms a square framing the crucible. (see picture)

As things heat up the feedstock will begin to soften and then melt. As the metal melts addtional feedstock can be **CAREFULLY** added to the crucible. Eventually you will have either fed in all your feedstock or the level in the crucible will be "full". I wouldn't overfill the crucible, if it gets half full go with that until you a clear idea of how exactly things will go.

Dross and slag will float to the surface of the molten metal. I removed this using a long handled tea spoon. ( see picture ).

Once you have a nice crucible of silvery molten metal ( more or less ) remove the two chimney bricks from the top of the furnace. Hook the crucible rod with the coat hanger hook and lift the crucible out of the furnace. Tilt the crucible to pour the aluminum using the wood piece to lift the bottom (see picture), this approach provides pretty good control on the pour.

In this case I used a muffin tin as the mold. It was handy, worked and readily discharged the aluminum ingots in an interesting muffin shape ( sort of ). As you can see from the picture I've done two melts with this and didn't actually get a full muffin because I ran out of feedstock.

I have a old cast iron stove i use to melt Al. I cut a old Co2 tank for a pantball gun in half and use that as a crucible, its high carbon steel with 1/16" walls and when I pre heat it to a deep red (and dont overheat the Al) I dont get any sticking and minimal slag. i just welded 3 legs@2" on the bottom and a "U" shaped handle for pouring on the top. gave it a football shape in a vice and good to go. it can hold about 3 cups no problem and can hit a good yellow hot without damage. By far the easiest to make and most durable crucible i have ever used.
<p>Some paintball CO2 tanks are actually made of aluminum. This could be a problem. I've seen other crucibles made out of empty propane tanks used for camping.</p>
I have featured your comment. You should consider doing an instructable as I believe there is a widespread need for crucibles amongst amateur metallurgists.
Will no one mention that what we commonly call aluminium is pure aluminium metal. Aluminium oxide is the major component of the dross you take the top of the melt.
<p>If you can't think of anything else to do with the molten aluminum, pouring it into a fire ant colony produces interesting results.</p><p>http://www.anthillart.com/</p>
I have been looking for an easy way to smelt aluminum and I do believe I will give this ingenious way a try. May I ask a few questions? <br> <br>Why doesn't the steel can crucible melt? Scratching my head on that one. <br> <br>The &quot;muffin pan&quot; seems to be steel too... Don't need cast iron? That would be great! <br> <br>Finally, I think I am going to cut the top off an empty mini propane can used for camping as a crucible. (Of course ensuring it is absolutely empty) do you think the sidewalls of this new crucible will be to thick to use in this application? <br> <br>Thank you for any response and showing me how simple can be best sometimes. <br>KeiferMax <br>
The steel can has a much higher melting point at about 2500 degrees F <br>while aluminum melts at about 1,221 degrees F <br>so you need a much hotter fire to melt the steel
The steel can has a much higher melting point at about 2500 degrees F <br>while aluminum melts at about 1,221 degrees F <br>so you need a much hotter fire to melt the steel
This is completely brilliant. And your Arthur Miller comment wasn't lost on me. No sir. OK, i have a couple of questions. <br>1) How long does the molten aluminum stay pourable? I'm sure it hardens pretty quickly, but how quickly? <br>2) Will silicone molds work, do you think? I'm not sure how high the temp goes in your smelting process. My most interesting molds are those made of silicone, so it would be great if they could be used. However, I have a feeling the temp will be too high. <br>3) OK, it's more than a couple of questions. Does the aluminum retain its flexibility? Could you pour it into a wire-shaped mold and make aluminum wire? <br> <br>Thanks for your time! <br>-- Lori <br> <br>
\i live in new zealand and i cant watch the video<br> why?<br> <br>
It is possible that the content is blocked due to copyright issues over the soundtrack. I have a notice from youtube that says this content has been blocked but it doesn't say where.
Very nice instructable, I will give a try on this one. I have only one doubt : I understand that the molds are sand made to permit the gas from the molten metal escape from it when solidifying, but, is possible to make molds from cement or something that I can use several times ? <br> <br>Thankyou for sharing this instructable.
I don't actually do forging so I can't provide any additional insight appropriate mold materials.
I tried this and i couldnt get the aluminum to melt. any suggestions?
I'd have to know more about your setup. I suspect either not enough charcoal or not enough air. Also what were you trying to melt, I cut up aluminum cans and didn't have much difficulty. A solid chunk might be more problematic.<br><br>What did you use for a crucible? Some have had difficulties with heavy metal crucibles, they absorb a lot of heat and can take a long time to get to melting temperature.<br><br>You could try banking earth around the sides, this will increase the internal temperature.
i used a tin can, like yyou said. i used a whole bag of charcoal, i was trying to melt soda cans. i used a leaf blower for air and it got extremely hot <br> <br>
I wonder if the leaf blower might be blowing too much air for this configuration? If there is too much air it might serve as a vent rather than a conduit. You might try a smaller fan if you have one. I was actually actually thinking of going the other way and seeing what results I could get with a small cooling fan.
I use a leaf blower, but the nozzle must be kept a few feet from the mouth of the furnace or the air/charcoal mix will be too lean and the fire may actually be colder (not to mention you could go through 50 lbs. of charcoal in 15 minutes). If you have a very large melter than you could hook the blower right up. However, if you do go with a leafblower DO NOT use wood charcoal. A leafblower used in a tall, thin furnace could give hardwood charcoal enough air to reach steel melting temperatures (as in a cupola), and ordinary bricks can't handle anywhere near those temperatures.
hey its been a while but ive been thinking of a new plan that uses these materials and a few modifications to increase insulation.
Cool, I look forward to your instructable. I've been toying with a modified design that uses a gas burner, solves the refueling and fire control issue.
unfortunately, my dad used my bricks for a different project with out asking, and they cant be retrieved(under at least 1 and a half foot of cement). With it being christmas, i cant afford the bricks. when i get them, i will test it out immediately.<br>NOTE: my bday is commin up, and so i expect to get cash to get bricks, so the inst. is coming soon.
I finaly did it!!! Instead of bricks, i just dug a hole and attatched a pipe to the bottom. worked great!!
Do you try again with a smaller fan?
Our county currently has a fire ban and im currently in High School so trying to find the time to do this and a secluded place is really hard, but i plan to use a smaller fan. just need a good, cheap fan.
does this furnice get the aluminum hot enough to make lost foam castings?
Since I'm not sure what the specific requirements of lost foam casting is I can't speak authoritatively to that. The aluminum melts, is pourable and so on ( depending on the crucible to some degree ). The charcoal is consumed so if the process is extended one may need to replenish the coals.
awesome instructable i will be trying this soon! <br>
lot of great info here. Gotta try this build some other places you all might like are www.backyardmetalcasting.com and www.metalcastingzone.com <br> <br>2 things that will help the casting are cover flux and degasser A quick search will turn up sources
In your introduction you claim that all aluminum scrap is really aluminum oxide. This is false. All aluminum scrap contains aluminum oxide - which is a clear ceramic with a melting point of 2000 degrees Celsius (3600 degrees Fahrenheit). The base aluminum melts at 660 degrees Celsius. This is why aluminum must be welded with an inert cover gas. Once the thin ceramic surface is fractured in air it oxidizes generating more aluminum oxide, until the over all heat builds up enough to fracture the oxide coating away from the edge - creating destructive puddling of the metal near the weld point. <br><br>In terms of your casting endeavor, the only significant issue is that the aluminum oxide coating guarantees there will be slag - no matter how pure your aluminum is.
I love this instructable. But the part where you said aluminum is aluminum oxide is only partly true. Pure aluminum metal gets an extremely thin layer of aluminum oxide. Also called alumina it is in itself a great refractory &amp; is extremely hard.
Cool. Have to try this with my heat gun.
You mean as the blower or the heat source? I don't think a heat gun will generate sufficient temperature to be useful but would probably make a dandy blower.
a blowr can give much efficient.
Your probably right though the extra heat could not hurt. I can always go to Goodwill and get a cheap hair gun and not wear out the heat gun..
Cold air is denser and thus has more usable oxygen. Hot air is just a waist of electricity.
Yo im wondering if the can is going to melt holding the aluminum
The can is (usually) made from steel, which has a much higher melting point than aluminum. Different steel alloys have different melting points, so I couldn't say what a &quot;tin&quot; can's mp would be without knowing the alloy, but it's generally around 1370 &deg;C. Elemental aluminum melts at 660.37 &deg;C, while Al2O3 has a melting point around 2,000 &deg;C.
Thanks for the amazing useful factoids.
It hasn't yet.
Love the idea, will try this soon! I drink a boatload of [citrus soda] and [cola] (I'll be fair, and not advertise, lol), and always save my cans for profitable scrap. I'll see how the scrap yard responds to processed ingots! I'm thinking I might even get a better price, since many impurities are removed, and pretty much did what the large recyclers do. The smaller recycling yards compact the cans, then ship them to a processor that either ships the cans to manufacturer (who processes the cans themselves) or shred and melt them down to ingots. I'll report my findings! :D
Please do, I agree that you should be able to get higher prices for ingots although you may have to hunt for it. If you have ready access to a source of biochar/charcoal you might be able to move up the food chain ( buy cans and sell ingots )....
The use of the grill cover is brilliant. I think this is going to be the design for the forge I am building. I don't have the resources for concrete, bricks will do fine.
Thank you for your kind words. I look forward to hearing more about your project.
I tested the design today and was able to heat treat two knives! It's great, thanks for the post :D I also manage to melt aluminum in it, so I plan to do a lot more in the future.
This looks really great! But does anybody have any idea on how to make a good mold for casting the liquid metal?
There are several instructables for making sand cast molds. Basically a box filled with a combination of fine sand and clay which is packed tightly around a form.<br><br>Arguably the cheapest and easiest cast.
what setting did you have your hair dryer set to? Did you let the charcoal burn awhile before using the blow dryer. If I use unheated air will that work?
Yes, any forced air source ( such as the blower output from an old fashioned rug vacuum ) will work. I used the cool setting on the hair dryer, its add no value as a heat source.<br><br>The more air that gets forced in the higher the temperature. Its not clear how hot this particular can safely get before the bricks begin to crack or the steel can crucible begins to soften and defrom.<br><br>I light the charcoal as one would a BBQ grill, when the flames had died down and grey ash begins to appear turn on the blower.
I have just had a brilliant idea! I hope its brilliant anyways... I got to a technical career school for computer, and in another class on the other side of campus is a machine tool shop with several lathes and the like. I know they get there Al peices from a factory that tosses the pieces out as scrap, being they must be a uniform size in there machines. I doubt they will give it up to me, but the machine tool shop in the school is going at is constantly, could the Al shavings from the lathes be used for this setup?
Actually I'd suggest you take the class, the ability to do basic machining such as milling and lathing will serve you well all of your life. Casting is just the first step, virtually anything useful will require additional machining. Plus you'll have access to a larger body of folks who can help making useful things. Trust me, they will want to get sand casting done as much as you want to do it!

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