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Just Poured Some Aluminum!

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  • Just Poured Some Aluminum!

    I had been wanting an aluminum foundry for a number of years now, but had never gotten around to building one. Finally, I decided to get off my arse and build one (because a friend of mine was getting married and I had no clue as to what to get her, but I figured that if it was something I made, she couldn't be upset if it was crappy or not).

    I managed to get it finished about a week ago, and let it sit to allow the lining to dry out. Today, what with it being a warm day and with there not being any better day for a week or so, due to weather, I fired that puppy up and melted some aluminum!

    Here's a pic of the foundry as its heating up:



    That pipe on the end goes to a hair dryer, which blows air to get the charcoal in the foundry to burn hotter.

    One thing I discovered is that standard aluminum cans are not worth bothering with to melt down, unless you can shred them up into small pieces first. Here's the crucible with a couple of cans and an old license plate in it.



    The crucible is about 5 inches in diameter and about 5 inches high, those cans melted down yielded less than an inch of metal in the bottom. I went through two kitchen trash bags worth of crushed aluminum cans and tossed in some aluminum that I had in a project I'd been working on, but hadn't gotten around to finishing. All that metal filled up about half the crucible when it finally melted, and I ended up with way more slag than I should have. And until I threw in the cannibalized parts from my one project, I was constantly opening the lid, putting in more cans, closing the lid, grabbing more cans, opening the lid, putting in more cans, and repeating. It probably took twice as much charcoal as it should have, and I only wound up (even with the metal from my project) with about 4 pounds of molten aluminum. The crucible could have held double that, I'm sure.

    Here's a shot of the ingots I cast:



    I'd always planned on my first heat being just a simple ingot making one, so I wasn't concerned about anything other than getting the stuff melted and into shapes that I could more easily re-melt later on, so I just poured it into some moist sand that had depressions made in it. Next time, I'm going to try and actually make the wedding present for my friend, and I'll be doing a lost wax casting, rather than a sand casting.

    Still, it was a lot of fun, and now that I know better, I won't be bothering to melt aluminum cans, so I won't be using up quite so much charcoal.

  • #2
    One small step... soon you'll be making BILLETS.

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    • #3
      That does look like fun. I'd like to try it too sometime soon. Somewhere I heard that the best scrap to use for casting is an old casting. Pistons, manifolds etc. Anyone else heard that?

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      • #4
        Originally posted by chipmaker4130 View Post
        That does look like fun. I'd like to try it too sometime soon. Somewhere I heard that the best scrap to use for casting is an old casting. Pistons, manifolds etc. Anyone else heard that?
        I don't know. I know that at the foundry I worked at, we tossed anything in that was of the right metal, casting or not. We made a wide variety of things, so it would seem not to matter (at least not on an industrial scale).

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        • #5
          @chipmaker4130 - my experience, my opinion - its a blast! And a good challenge for me to get low defect castings. lol

          On alum for home foundry, my experience:

          1. Cans are a bummer, vapor from coatings is BAD for your lungs & make lots of dross, their large surface area oxidizes making more dross. Yeild is about 40%, 10 lbs cans makes about 4 lbs ingot. And like Tucherfan said, you use lots more fuel w/ lid open to toss in more cans. Almost anything else is better.

          2. Extrusions (most things that weren't previously cast) melt fine & pour OK, but if you want to machine the castings you'll be sad. They will be very "gummy", alum. sticking to drill bits, mills & cutters. Crappy finishes. Just a bummer. If you add some copper to the melt (say 3-6%), the results will be better. The copper will dissolve in molten alum in a few minutes, no need to heat to coppers melt point.

          3. Previously cast items usually make pretty good castings. They melt & pour a little better & machine well.

          Hope it helps, cuz its a blast!
          uute

          PS. Do try to aviod greasy or oily scrap - makes for more hydogen in melt = porous castings. Little bubbles all thru = pits on any machined surface.
          Last edited by uute; 11-22-2012, 07:12 PM.

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          • #6
            Another thing with cans is that some of the ones I used still had some liquid in them, and I got a few nasty "burps" as I was putting them in. Thankfully, the bulk of the metal that came out just splashed on to the side of the crucible, and didn't come raining down on me. I'd forgotten what that was like, until it happened to me today.

            (The foundry I worked at stored its metal outside and the days after it rained always made for some "interesting" heats, as the furnace would "burp" whenever a wet load of metal was shoveled into it. After a while, you didn't pay any attention to it, until one day when the furnace operator ran from a wet load!)

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            • #7
              Casting metal is fun and addicting. I did this cross for a silent auction at the day care my son goes to. I did this out of bronze. A simple impression form a cast-iron one I had. And an open mold, I just band sawed off the over pore and machined the back flat. This would make a great wedding gift with the names and date engraved on the back.
              The links to my cast cross.http://bbs.homeshopmachinist.net/thr...light=jeremy13

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              • #8
                Tuckerfan, Do you have a Freecycle group near you? Old lawnmowers are often given away on Freecycle. I've collected and melted several. Their blocks, heads, pistons and rods are all good quality cast aluminum. The best to be had, so I've heard is aluminum car wheels.
                I have gone the can route myself and came to the same conclusion. I had heard of the poor machinablity and high dross of popcanium, but like so many others I had to find out for myself.
                Haven't cast much usefull stuff, other than consolidating 2 ea 5 gal. buckets of muffin tin sized pucks, most melted over charcoal in an old mop bucket, as you did.
                Next step is to build a propane burner.
                I was given a huge furnace but haven't used it yet.

                Chuck

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                • #9
                  Now that you mention it, I've got a dead lawnmower in my shed that I've partially torn apart. Of course, getting it out of the shed and completely tearing it apart is going to be a bit of a challenge. Wish I had remembered that before I started the foundry up today.

                  Hadn't thought of freecycle, either, will have to give that a check to see what turns up. Might also be able to get some scrap aluminum from work as well. We mostly work with stainless, but there's a few jobs of aluminum that we do every now and then. Its plate and bar stock, but I've got plenty of scrap copper around here, so I can mix it.

                  I'd never heard anybody say anything about aluminum cans one way or the other. I'd figured that it'd take a number of cans to get a decent amount of metal, but I had no idea that it'd take so many.

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                  • #10
                    The comment about oily scrsp is a good one. I melted about four old barbeques and the metal, although cast aluminum, was sooo greasy it was about 1/3 slag.
                    Watch out for chainsaw castings! There is a chance that they are magnesium and THAT will light up your day!
                    Duffy, Gatineau, Quebec

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                    • #11
                      Heh. I remember when I worked at the foundry and they had a special project to cast that I overheard the furnace operator and the mold setter talking about, when one of them mentioned that it was being made out of magnesium. I immediately asked them if they knew that the stuff caught fire very easily. Nobody had bothered to tell them about that, nor did they know that there wasn't really anything they could do to put it out once it caught.

                      I was so glad that I'd moved off the pouring crew and into the shop, because the stuff caught fire. Thankfully, nobody was hurt, but it damaged the furnace and the castings were useless to the customer (turned to powder the instant anybody tried to touch them).

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                      • #12
                        Now that you have been bitten by the casting bug I sould warn you that smelters are never big enough This is one crucible full-
                        I just need one more tool,just one!

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                        • #13
                          Originally posted by Tuckerfan View Post
                          Heh. I remember when I worked at the foundry and they had a special project to cast that I overheard the furnace operator and the mold setter talking about, when one of them mentioned that it was being made out of magnesium. I immediately asked them if they knew that the stuff caught fire very easily. Nobody had bothered to tell them about that, nor did they know that there wasn't really anything they could do to put it out once it caught.

                          I was so glad that I'd moved off the pouring crew and into the shop, because the stuff caught fire. Thankfully, nobody was hurt, but it damaged the furnace and the castings were useless to the customer (turned to powder the instant anybody tried to touch them).
                          Your employer has a legal obligation to provide the MSDS. There is an obligation to familiarize employees with that information. The employee has an obligation to consult that document regarding any material they are not familiar with. Lots of blame here.
                          Adding copper will not solve your casting problems. Your best solution is to melt similar items to what you plan to cast. The most critical element, silicon is already there. This is what makes the heat flow into little thin areas of the mold.
                          Castings are for casting. Wire is for drawing. Sheet is for rolling. Extrusions are for extruding. It ain't rocket surgery.

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                          • #14
                            Tuckerfan, Be shure to test any scrapped castings for magnesium. Shave a small piece from suspect casting and try to light it using a propane/mapps gas torch. If it burns brightly do not bother melting it.
                            You can break down the lawnmower castings into smaller pieces to fit your crucible by heating them to "Hot=Short" over a charcoal or wood fire. Heating to hot-short is just below melting point. Makes it soft enough to break up into pieces.
                            I have posted on Freecycle that I wanted old broken mowers and gotten several.
                            There are additives you can add to the melt to help de-slag and de-gassify. Can't remember what they are at the moment. Google de-slag or de-gasify aluminum and you should find info.

                            Chuck

                            Chuck

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                            • #15
                              I saw somewhere that when breaking up larger castings like wheels, mower housings, etc to use a hydraulic log splitter. Looked like a good idea.

                              Also, salt of some sort is used to de-gassify the melt.

                              Brian
                              OPEN EYES, OPEN EARS, OPEN MIND

                              THINK HARDER

                              BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                              MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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