Melting scrap aluminum

[JimGlass]

I have 15-20 lb of scrap aluminum I would like to melt down. What could I use for a container to melt the aluminum?

I'm thinking about using my heat treat oven for a heat source.

Thanks,
Jim

[RONALD]

Jim, I melt lots of aluminum in a silicon carbide crucible. I have a McEngelvan B30 furnace and use a number 30 crucible. The numbers on crucibles indicate how much aluminum they can hold, a #30 holds 30 pounds.

For a heat treating furnace, you will have to use a much smaller crucible, and will not be able to melt all twenty pounds at once. I have a heat treating furnace I recently acquired, but have yet to connect the gas. Such a furnace can easily heat up the Al.

Of course, it depends on the type and condition of the Al, as to if you will get anything useful. I use scrap for things that are not important, and have 1500 pounds of A319 ingot, I bought from the closed foundry of the school I taught at for .50/pound, for important castings.

[tomc]

you can use a piece of pipe and weld a bottom on like we did. We will use a propane furnace instead. A little heat and a big hammer gave us a nice lip. We will use the bolts for our pickup handle to grab.

Tom C.

[JimGlass]

Hey Tom:
I thought the aluminum should not come into contact with steel? What you have looks great. If what you have works, I'll probably go that way.

I would like to mold the aluminum into 1 or 2 pound ingots for later use.

Also have aluminum chips I would like to melt down. Puting the scrap and chips in the trash feels like throwing away money. I may try getting into casting someday. At the CNC workshop, I saw a demonstration on foam casting and was very impressed.

http://www.cnc-workshop.com/

This is all 6061.

Looks like the graphite crucibles could be the way to go. Could I use
cup cake pans for molds? The tapered side walls should release the aluminum when solid.

Jim

[steamin10]

First nice job on forming the iron pipe for vessels. Second, they aren't worth a dang, unless you coat them. Paint them with slip from ceramics or weld barrier, (its made from chalk), and you are good to go. I used a cast iron pioneer dutch oven for melting out turnings and scrap for many years with mixed results. A plumbers pot was way too small .

The point here is to keep the aluminum as chemically clean and stable as you can. DO NOT add any aluminum that has iron filings, rivets, or saw trash in it. ANY IRON in the melt will dissolve and be picked up into the aluminum, making it shrink badly, give large crystals, poor color skin, and pastey pouring, with poor detail (if it pours at all), and become quite brittle. Basically ruining the properties you use aluminum for. When you pour this into ingot form for future use you can actually see the diferences between 'good and 'bad aluminum stock. You can shake and bake a batch from known feedstock, and use small amounts of your bad ingot on selected projects.

Just because you start with 6160, does not mean you will end up with that. The process of melting in the presence of any other materials can change the small alloy contents and make it something else. Aluminum, being a very active metal is very changable in the small quantities we deal with. Basically, melt fast, get to temp and pour in as little hold time as possible.

As far a pigging is concerned, I keep scrap and turnings in 5 gallon pails with lids on to keep it clean, and just add to a melt to top it off. I have several home made ingot molds that are 2 inch angle welded so that the 10 inch lengths describe a tray that has four triangular channels. The triangular pigs absorb heat well and melt into a puddle quickly, the other mold made from channel makes bricks that sometimes give me fits jammming on other scrap and while heating, expand, and sometimes push on the hot vessel bending it. That makes me uneasy. I use carbide now for my melts and find it most economic for aluminum, and necessary for bronzes.

I hope this helps you to get the quality you need. If you do any casting, it doesnt make sense to work on something that has inferior metal quality in it. So keeping the metal quality high is what I am preaching to the choir here.

[Lew Hartswick]

Also have aluminum chips I would like to melt down. Puting the scrap and chips in the trash feels like throwing away money.

Jim

Jim trying to melt chips and swarf is a loosing prop. It all turns to dross
unless done in an inert or reducing atmosphere. There is jut WAY to much
surface area per volume. They tried to melt soft drink cans at school and
got nothing but scum. It would be real good if someone could come up with
a practical system to reclaim the turnings, we certainly produce enough of
that to keep the foundry class in business.
Some sort of "liquid" with a high enough boiling point to keep the swarf
submerged while melting would do it . :-)
...lew...

[steamin10]

Ya, whenever I 'use up' turnings in a melt, itis always on a puddle or part ladle that is already hot so an infuser rod is used to push the scrap under and melt quickly. Also a little fluxing will help clear the melt of junk and gasses. HTH pool chlorine tablets are what I use, crushed with a hammer in a burlap. about a half teaspoon does OK for me infused into the melt with a screen cup, or invert cup rolled in Al foil pack works, stirred well in. Carefull of the fumes here. Chlorine is dangerous when cast off, so goood ventilation is needed.

I have also tried the folley of melting pop cans. Turn them in and use the money to buy heavy scrap , like auto wheels, transmission cases, and cut or break them up. You will be ahead.

[oldbrock]

When we cast aluminum in my high school class I quickly learned not to include any wrought aluminum in the melt. They are not designed for casting. I had the best results using cast pistons. Went around the auto shops and collected old pistons, not forged. The worst material for clean sharp castings was bell housings. Don't know what they put in them but it casts up like s**t

[tomc]

We had to try a melt and it went well.

Tom C.