Smelting/Pouring/Casting of Aluminium ?

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Smelting/Pouring/Casting of Aluminium ?

Post by Die Judicii » 13 Jan 2023, 10:35 pm

Does anyone here have hands on experience with the abovementioned ???

I'm thinking of using old alloy mag wheels as base supply.
Or, any suggestions of something harder wearing and higher tensile than alloy wheels as a base supply that may be readily available.

When talking to an alloy wheels supplier today, I was told that the same grade/hardness/tensile strength is used in the manufacture of the entire
wheel,,, including the wheel stud/hub area.
Would smelting and subsequent pouring of,,,,, result in a lower/poorer quality metal ?

I know what I want,,,,, but lack in the technical knowledge of such things.
Any advice,, pointers,, gladly welcomed.
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by bladeracer » 14 Jan 2023, 12:12 am

When I was a kid I used to carve things in wood and pour molten aluminium in them to make stuff, nothing serious though, just messing about. As an adult I did look into casting aluminium and magnesium for race bike parts but determined it was going to be far too finicky for most things (like engine covers) and impossible to control for important things like wheels and frame components. At that time I could buy various aluminium alloys from Capral for $15/kg so it made more sense to use known stock and cut it to what I needed than risk casting imperfections and burns.

It's just melting, smelting starts with bauxite and a few million dollars worth of equipment.

Yes, I would expect a single cast item to be all of one alloy. A rim bolted to a hub could be a different alloy though. I don't recall whether I looked into what you end up with when you melt different grades of alloys but I would expect it to be significantly lower grade.

I don't know but I would expect to lose quality in casting in a backyard situation. If you want a 7xxx series alloy for example I would use billet and machine it, I wouldn't melt it and expect a cast piece to be of that same grade. I would just assume it'll end up being 6061 and work on that.

EDIT: I did make engine covers by simply stacking plate up until I had the required height and bolting them all together. Very solid too so only damage when crashing was grinding the end off which was very easy to replace.

Die Judicii wrote:Does anyone here have hands on experience with the abovementioned ???

I'm thinking of using old alloy mag wheels as base supply.
Or, any suggestions of something harder wearing and higher tensile than alloy wheels as a base supply that may be readily available.

When talking to an alloy wheels supplier today, I was told that the same grade/hardness/tensile strength is used in the manufacture of the entire
wheel,,, including the wheel stud/hub area.
Would smelting and subsequent pouring of,,,,, result in a lower/poorer quality metal ?

I know what I want,,,,, but lack in the technical knowledge of such things.
Any advice,, pointers,, gladly welcomed.
Last edited by bladeracer on 15 Jan 2023, 7:09 pm, edited 1 time in total.
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by Noisydad » 14 Jan 2023, 1:48 pm

Use the search bar and search for “Making Stuff part 2” to find a photo heavy thread I posted years ago about casting my own reloading press. That press is still going strong and is my regular workhorse for full length sizing cases, sizing cast bullets, compressing BP, riveting leather etc.
There's still a few of Wile. E Coyote's ideas that I haven't tried yet.
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by bladeracer » 14 Jan 2023, 2:04 pm

That is pretty awesome.
Did you get the cast at the first pour or did it take a couple of goes?

I met a bloke years ago that couldn't get an alternator cover for his bike so he patched his damaged one up well enough to do a sand cast and poured himself a new one, and it looked bloody good. That's what got me interested in looking at it myself. But I'm a carpenter so I just work better with stock materials I can cut and weld or bolt together to make what I want. Bolts and screws do significantly add mass, which sucks for bike parts, but they also make a part modular so when you crash again hopefully you only need to make one or two pieces to repair the original you made - front and rear subframes, battery boxes, rear sets, mufflers and such.

Noisydad wrote:Use the search bar and search for “Making Stuff part 2” to find a photo heavy thread I posted years ago about casting my own reloading press. That press is still going strong and is my regular workhorse for full length sizing cases, sizing cast bullets, compressing BP, riveting leather etc.
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by Noisydad » 14 Jan 2023, 2:40 pm

I deliberately poured a couple of samples first to see where shrinkage would happen so I could position risers to feed the shrinkage and eliminate them. Still have the wooden patterns too.
There's still a few of Wile. E Coyote's ideas that I haven't tried yet.
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by bladeracer » 14 Jan 2023, 3:45 pm

Noisydad wrote:I deliberately poured a couple of samples first to see where shrinkage would happen so I could position risers to feed the shrinkage and eliminate them. Still have the wooden patterns too.


I would would probably just cast a solid billet then cut it into the shape I want :-)
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by Noisydad » 14 Jan 2023, 4:00 pm

It may well have been easier to fab a press but….thousand degree fire AND liquid metal!
There's still a few of Wile. E Coyote's ideas that I haven't tried yet.
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by bladeracer » 14 Jan 2023, 4:14 pm

Noisydad wrote:It may well have been easier to fab a press but….thousand degree fire AND liquid metal!


Fun, but definitely not today :-)
BOM says we got to 35.4, but it felt like more to me. 61C on the gravel outside the door with the thermo gun.
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by on_one_wheel » 14 Jan 2023, 5:45 pm

I do have good experience in foundries.

If your mags actually contain magnesium it would be unwise to attempt to melt them / it without doing so in an controlled atmosphere to prevent the magnesium from combusting into a hot as the pits of hell, blinding white fireball.

If you're sure it's just aluminium then it's a pretty straightforward process, just ensure it's bone dry and your sand isn't too wet as it will explode violently otherwise.

Aluminium of all grades is great to work with, it melts at relatively low temp, flows well and machines easily.
Ideally don't get it so hot that it glows, it should look silver not red as red hot aloy leaves a very rough finish. :thumbsup:
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by Blr243 » 15 Jan 2023, 5:54 pm

I tried melting alum once with oxy acet. Not hot enough. Buggered if i know ho to melt it ?
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by bladeracer » 15 Jan 2023, 7:00 pm

Blr243 wrote:I tried melting alum once with oxy acet. Not hot enough. Buggered if i know how to melt it ?


MAP gets to 2000C. Can't recall what I used as a kid but it wasn't acetylene. Most likely a bunsen burner from my chemistry set but I can't see that getting hot enough for aluminium without a crucible. I'll ask my brother, he might remember.

I remember now, I did it in a little cast iron pot on the gas stove. The pot was too small to sit on the top so I had to balance it between the points of the grate. I also recall the time I tried to straighten a brake lever using the gas stove and it melted, the molten metal fell into the gas orifices and stopped the stove from working until I pulled it apart and melted the aluminium out of it - oops :-)
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Re: Smelting/Pouring/Casting of Aluminium ?

Post by on_one_wheel » 15 Jan 2023, 7:20 pm

Depending on the grade / blend of aloys it'll melt somewhere from 550c to 700c

We use a basic diesel furnace with a blower.
The foundry stopped using heating oil when a reliably clean supply proved difficult.
Diesel is fed under gravity through a needle valve for flow adjustment, through a small hole, atomised with a venturi that's feed air from the blower.
Air / oil spray enters the bottom of the furnace on one side and swirls around the crucible, it exhausts through a large hole in the furnace lid.

You could make a neat little furnace around the size of a old tin garbage can without breaking the bank, the furnace cement is a little pricy but you wouldn't need a whole heap to make something of that size.
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