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Hi all,
I've been cutting away at aluminum for about a week and a half on my lathe. At one point, I had so many chips that I thought it wise to melt them down and cast some alumuffins. When I tried to melt my chips they just turned into dross, or crud, or whatever ya call it. Am I doing something wrong? Everything else melts, just not the chips. I'd hate to just throw them all away.
It has something do with to much surface to air ratio and it looks like dross, such little pieces and don't melt they just burn up. I figured by buying many hundreds of pounds of this stuff I could melt it down but was wrong. Tried to melt it when I had half a pot of melted aluminum and us my ladle to push it under and still it didn't work. So gave up maybe someone else has had better luck.
interesting... i wouldn't have guessed that. i plan to build a small blast furnace soon though, so i'm sure i'll run into some of these "interesting" things. does the alloy play a part?
You need an inert gas furnace or a vacuum furnace. Anything to remove atmospheric oxygen which simply oxidizes the chips to aluminum oxide, a.k.a. dross. As flyeribe says it is a surface are to volume thing.
If you are feeling crazy you can mix them with iron powder and ignite them to get a thermite reaction with lots of bright white flames, smoke and a pool of molten iron at the end. Not the sort of thing you should do inside; actually not really the sort of thing you should do.
An open mind is a virtue...so long as all the common sense has not leaked out.
My thoughts were to mix those chips with epoxy to make plastic aluminum.
unlike the epoxy granite, this would be machinable, yet strong, and would give a machineable layer over epoxy granite if casst in layers.
Throw in the iron powder and you have something like the solid propellant used in the Shuttle boosters.Originally Posted by BEARINGMAN
On a serious note: I have seen this idea mentioned before and wonder how well the epoxy will stick to the aluminum or whether it is just a mechanical bond on the rough surface.
An open mind is a virtue...so long as all the common sense has not leaked out.
Aluminum oxidizes immediately in air-You never really see alluminum, jus the clear alo2 coating. with small enough pieces its mostly alo2--dross. it really isn't worth the time and fuel to melt al chips or turnings.
In the words of the Toolman--If you didn't make it yourself, it's not really yours!
Remember- done beats perfect every time!!
I seem to recall one guy who successfully melted chips. It seems that he built a press and packed the chips into compressed slugs about the size of a soda can. This allowed the heat transfer to the chips while effectively reducing the surface area. I don't recall how many thousand pounds of pressure that he use but it was significant pressure, not just something like a trash compactor. He used a thick wall container, probably with some taper. I don't recall exactly how he got the slugs out (that's why I think it was probably tapered).
Alan
How about starting with some molten aluminum then adding the chips to that?
I tried that. It doesn't work.
Geof, thanks for that post regarding the reduced atmosphere vacuum. It seems like that's the ticket. It also solved that aluminum oxide issue for me. I was wondering how I'd get that stuff.
Someone once showed me how to get aluminum oxide through a chemical reaction using liquid plummer or something of that sort. I dunno, but I do know that it's dangerous.
What a shame, all these chips that'll just get thrown away. I'm officially bummed out over it.
When you generate enough volume/mass of chips they don't get wasted. We send a few thousand pounds a month for recycling and the procedure is more or less a combination of what acondit and randyf1965 mention. The chips are compacted in pucks (also called briquettes) and are then melted in already molten aluminum. The compacting machine does use a decent force; for making pucks around 3" diameter and about 1" thick I think it might be close to 100 tons.
This thread discusses making a chip compactor and post #16 shows a picture of a puck I made in a simple press.
Chip Compacter
An open mind is a virtue...so long as all the common sense has not leaked out.
I googled the idea and saw mention of the danger of enclosed pockets of liquid exploding after a slug being immersed in molten aluminum. One of the patent abstracts talked about a washing, drying and then compacting sequence. Another just washed and dried and then sent the chips into a furnace where they were immersed in molten aluminum. It looks like the processes are non-trivial. I couldn't find the post from the foundry forum I used to haunt.
Alan
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