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  • Melting aluminum

    Does anyone here cast aluminum? I did in high school, but haven't since. Here's the thing, I'm cleaning out the garage. And I have lots and lots of cast aluminum scrap. Lots of pistons, engine cases, etc. (I'm a motorcycle mechanic) I'm not set up to do any casting now, but I'd like to try my hand at it down the road. But im not going to make the investment now. So I'm thinking I'd like to hang on to all this scrap, but it's also a sizable pile spread out in various boxes. It would be nice if there was a way for me to melt it and turn it into easily stackable and storable ingots. How would one do that if one didn't possess a furnace or molds and whatnot? Could a crude crucible be made from say, thick walled pipe, and be heated in a good hot fire to pour it into some sort of home made ingot mold?

  • #2
    I do, and there's lot of decent (and not so decent) info on the web. As for casting the aluminium into ingots... I gave up, recycled a bunch I had collected and got near nothing for it. It takes time and fuel, and after a while it starts to seem rather pointless, unless you have them in abundance. I realised that I had already cast enough ingots to complete every project, real or imagined, likely or absurdly into "never going to happen" territory. Why keep sorting scrap and casting ingots? Why not do something with what you already have?

    That said, I do just about everything wrong and I still manage to get useful blocks of aluminium without, so far, killing myself. I did buy some ramable refractory to make my furnace but otherwise use shop-built steel crucibles instead of the store-bought ceramic ones. I'm still learning the art of sand-casting but have had reasonable success just using steel moulds. I don't think I'll be casting aircraft parts or new pistons for my car, but blocks for this and that are pretty easy. It's actually quite fun.
    Last edited by fixerdave; 03-23-2012, 01:25 AM.
    http://fixerdave.blogspot.com/

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    • #3
      A home foundry to melt aluminum is pretty easy to make.
      I read Gingery's book about it, and tried it myself (although I'm no pro).
      A 5 gallon metal bucket, lined with fireclay.
      a 2" hole in the side, near the bottom, for the forced air input.
      Use your wife's or girlfriend's hair-dryer to force air into the hole.
      Rig-up a fireclay lid with a 2" opening in the middle.
      Steel pipe will work for a crucible.
      Fill halfway with regular charcoal, light, force air thru it.
      Melt!
      Make a simple sand mold with Silica sand (NOT playground sand).
      (obviously these are the crib-notes. Actual reading about the subject is recommended)

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      • #4
        Melt in a steel pipe with a cast iron cap for a bottom ( 4" or so) on top of a gas burner or in a bed of charcoal
        Pour into a cupcake tin for ingots.

        Don't need a furnace

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        • #5
          I could be wrong, but I thought I read that CI and perhaps steel crucibles used to melt aluminum will add iron to the mix and that is undesirable.
          Paul A.

          Make it fit.
          You can't win and there is a penalty for trying!

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          • #6
            check out Lost & Foundry's site lot's of good info there , here's a link to a page called hobo casting, http://www.foundry101.com/Free%20Furnace%20Plans.htm

            I bought one of their casting set up's and it's been a lot of fun .

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            • #7
              I once accidentally cast an aluminum ingot, so it can't be that hard. Burner barrel, was burning all kinds of wood from a friends RV he was taking apart, Lots of aluminum trim on the wood.

              Next morning, theres an ingot on the ground next to the burner barrel, with a trail running from one of the vent holes in the bottom. Looked very clean too. I guess it melted and soaked through the lighter wood/ash and out a vent.

              I have seen lots of popcans in a fire turned into little lumps as well. And other misc aluminum recovered from the ashs of fires of burnable debrie as small molten lumps.

              Not recommending it as a way to make ingots, Just saying it does not take much to melt aluminum.

              Its also worth much more if you scrap it now, then after spending a lot of money and time on fuel to turn it into ingots. Melting stuff twice is a bit silly too.

              Consider scraping anything thats low weight for the volume in your scrap pile it takes up.
              Last edited by Black_Moons; 03-23-2012, 01:52 AM.
              Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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              • #8
                I have a foundry I've built....just haven't finished the project with a crucible and tongs.

                I'm going to go the lost foam route just to keep it simple.

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                • #9
                  Originally posted by Paul Alciatore
                  I could be wrong, but I thought I read that CI and perhaps steel crucibles used to melt aluminum will add iron to the mix and that is undesirable.
                  Yeah, I read that too. I think it all depends on the standards you're working towards. Like I said, I'm not making aircraft parts. I've also read that you can coat your tools and whatnot with graphite to provide a barrier. Never tried it as I never had any trouble with stuff melted and poured into steel. It comes out clean, no bubbles, works like aluminium. It's all from scrap anyway and I can't vouch for the zinc content or any other alloy. It melts, it pours, and it made decent soft-jaws for my vice etc... good enough for what I'm doing - so far. When I started, I figured I could buy the ceramic crucible if I needed it... not so far.
                  http://fixerdave.blogspot.com/

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                  • #10
                    Before I became obsessed with mechanical things ie moving sculpture I cast quite a lot of bronze


                    This is my son and me with about 30kg of 1100 degree centigrade bronze between us. Strangely he hasn't offered to help again
                    Probably the biggest piece was this horse


                    Built the foundry ourselves.
                    I still cast work but they are part of moving pieces

                    I have a project I'm working on now that I hope to post pictures on soon.
                    Aluminium is easier in that the temperature is lower but the shrinkage can be hard to deal with
                    regards
                    david

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                    • #11
                      It is a good idea to melt scrap aluminium into ingots before using it in a project, the process gets rid of oil dirt and grunge that could otherwise affect your 'good' castings.

                      A good ingot mould is a piece of angle iron with a plate welded across each end, this makes long skinny sticks of aluminium which are easy to stack and melt quickly when you want to use them.

                      A good hot fire, wood or charcoal will be enough to melt aluminium, and a steel pipe crucible will suffice. As others have said molten aluminium dissolves steel quite readily so check the soundness of your crucible from time to time. One good method of extending the life of a steel crucible is to heat it red hot when empty and let it cool down before you use it for a melt. This gives the crucible a coating of oxide which protects the steel from the aluminium.

                      There is lots of good info here. http://alloyavenue.com/vb/forum.php

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                      • #12
                        Originally posted by nitsuj
                        Does anyone here cast aluminum? I did in high school, but haven't since. Here's the thing, I'm cleaning out the garage. And I have lots and lots of cast aluminum scrap. Lots of pistons, engine cases, etc. (I'm a motorcycle mechanic) I'm not set up to do any casting now, but I'd like to try my hand at it down the road. But im not going to make the investment now. So I'm thinking I'd like to hang on to all this scrap, but it's also a sizable pile spread out in various boxes. It would be nice if there was a way for me to melt it and turn it into easily stackable and storable ingots. How would one do that if one didn't possess a furnace or molds and whatnot? Could a crude crucible be made from say, thick walled pipe, and be heated in a good hot fire to pour it into some sort of home made ingot mold?
                        If it were me (and it was a few decades ago) I'd cap a piece of steel pipe with a threaded cap or plate for a pot and use a coal fire (with a bit of draft) a charcoal fire (again a bit of draft helps reduce heat time), or a "weed burner" propane torch (where I grew up, there were lots of locally made "tiger torches" around. IIRC 200,000 BTU burners)

                        Any heat source that will raise about 4" of a 1" bar of steel to dull red heat will melt aluminum. Refer to a blacksmith color scale for pyrometer or infrared temp readings that correspond to the color (should be +/- 1400 F) Aluminum melts at just under red heat.

                        Ingot molds can be as simple as a stamped steel muffin tin or a few pieces of angle iron.

                        For critical castings, direct contact with steel is undesirable as some minute changes in chemistry can result. On a hobby basis, the minute additions are, IMHO, irrelevant as the feedstock is largely mystery alloy anyway.
                        Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

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                        • #13
                          For crucibles I've used simple grapefruit juice cans, the large 46 oz cans, in my Gingery charcoal furnace.

                          To be on the safe side, I only used each can for one melt, and don't let it linger in the fire for a prolonged period after the metal is molten.. After a few melts with those I made a crucible of thick walled pipe, but it actually seemed to deteriorate faster than the juice cans.

                          For molds I've used salmon cans; the type that are tapered or flared from bottom to top. The flared shape permits extracting the ingot easily.

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                          • #14
                            Originally posted by fixerdave
                            . I've also read that you can coat your tools and whatnot with graphite to provide a barrier. Never tried it as I never had any trouble with stuff melted and poured into steel..
                            Graphite is CARBON and it will be all burnt up in a shake. The coating is
                            a refractory material put on as a slurry and cured.
                            ...Lew...

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                            • #15
                              Originally posted by bob ward
                              A good ingot mould is a piece of angle iron with a plate welded across each end, this makes long skinny sticks of aluminium which are easy to stack and melt quickly when you want to use them.
                              Another good ingot mold is a piece of channel iron about 12" long and capped on both ends.

                              One thing no one has really addressed are the safety concerns. Aluminum melts around 1250 degrees F, plenty hot to cause serious burns. PPE is a must and should include at the minimum safety glasses AND a face shield, welding gloves, apron, jacket, and arm protectors. Liquid aluminum splatters and goes right through "normal" work clothes. Naturally only clothes made from natural fibers (cotton, wool, etc) should be worn. Man made fibers such as polyester, nylon, etc are asking for trouble.

                              In addition care must be taken not to accidentally add any liquid to the melt while adding additional material. The coefficient of expansion of water to steam is 1600:1 and happens instantly (think explosion). This also effects where one should pour. Do not do so on concrete as any spills will create concrete shrapnel. Pour outside on the ground or if you must pour inside do so on a bed of sand or at least a piece of plywood or OSB.

                              I've made my own foundry using an old water heater lined with fire brick and a couple of squirrel cages from HVAC units and fired with coal. Worked great. Flasks in which to make your molds are very easy to make and it is easy to make a molding bench from a 55 gallon drum split vertically then laid horizontally.

                              One of the best manuals for casting is the US Navy's Foundryman book available from Lindsay Publications.

                              BTW, dogdoctor that is an example of an excellent set up and the horse is a fine piece of craftsmanship. Well done.

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