PDA

View Full Version : how can you melt aluminum without a furnace



welder
20th Sep 2011, 10:27 PM
I was wondering if there is a way to melt aluminium with out a furncance. as i have a pile of extrusion i want to cast into ingots. also is i possible to melt aluminium gas cylinders as i have an g size aluminium helium cylinder that i have no use for.

kraits
20th Sep 2011, 10:46 PM
easy, build a fire in the weber, aluminiums melting point is around 660C and the oxidised layer is slightly higher but, you can acheive these temps in the bbq no worries, all you need is wood, not heat beads and something to fan it with, also will need a crucible of some description. you can use a stainless pot if you got a disused one laying around but your going to lose the handle so get tongs.when your melting dont stir it around, just let it melt and make a spoon with an extra long handle to scrape the dross off the top which will reveal the molten aluminium. take my advice and don't pour it into pipe or rhs, your going to have a hell of a time removing it, will have to slice it in half to get it out. pour the molten metal in, pipe/rhs heats up and expands, when it cools its tighter then you know what.make the mould of two halves either hinged on one side, wired together or bolted together.

jhovel
20th Sep 2011, 11:15 PM
Any container that can be heated to around 700 deg C allows you to melt it.
However you need good insulation to get things that hot without heating the rest of the town. That kind of insulated container is called a furnace.
Google "melting aluminium" and you'll find all kinds of solutions.
You also need a burner - gas, coke or oil. ELectricity is feasible but more complicated.
You should PM RayG for assistance!

Please don;t melt the gas cyclinder. The day after you do, you will find a use for the heavy wall aluminium pipe between the ends! Just cut them off and melt them if you really must - and put the pipe section in your metals stock.
Joe

kraits
20th Sep 2011, 11:35 PM
However you need good insulation to get things that hot without heating the rest of the town. That kind of insulated container is called a furnace.
Google "melting aluminium" and you'll find all kinds of solutions.
You also need a burner - gas, coke or oil. ELectricity is feasible but more complicated.


don't worry, char coal will burn at a higher temp then coke, given enough air is pumped into it, only problem is that it's not as efficient as coke. as for heating up the whole town i dont think so. if your sceptical next time you have a bbq, throw in an off cut (when you finnished cooking) and dont even give it any air, it will melt, ive melted copper at home in my coke forge and poured ingots, no problem and as i recall its melting point is around 1200C or more.

RayG
21st Sep 2011, 12:15 AM
The simplest I can think of, is dig a trench in the ground, fill it with charcoal, get a hair dryer and some steel pipe, maybe 2-3 ft long that you can fit the hair dryer to, use duct tape to hold the hair dryer in place.

Get the charcoal burning with newspaper and a bit of air from the blower. Put the aluminium into a steel cooking pot. Adjust the hairdryer speed to give a nice hot bed of charcoal. Before too long (maybe 10 minutes or less) you will have molten aluminium.

Ok that's the easy part... to cast a particular shape, you need a pattern and some technique. The easiest casting technique for backyard casting is called lost foam, I won't go into detail here, you can google for it. But basically you make a pattern out of polystyrene foam and bury the patten in a bucket of sand, then you pour the molten aluminium into the pattern, the polystyrene foam just evaporates and the aluminium fills the space..

Now for a safety warning, casting aluminium is potentially more dangerous than casting bronze or copper. The reason for the danger is a bit subtle, aluminium is very reactive, it reacts with air very readily to form aluminium oxide, every piece of aluminium you have ever seen is coated with a thin layer of oxide, when you have molten aluminium, it can't form that protective oxide layer, so it reacts with any oxygen that it can find, if molten aluminium comes in contact with water it's so reactive it will strip the oxygen out out the water (remember water is H2O) leaving hydrogen gas, which in turn will burn ( more likely explode) when it bubbles out of the molten aluminium and combines with the oxygen in the air. (I'ts called a hydrogen explosion)

It's a problem that is peculiar to the chemistry of aluminium, particularly where scrap aluminium is involved that might include cans that have the dregs of some drink or water trapped inside... some of the biggest foundry explosions are molten aluminium... be careful

So, make absolutely sure you have NO water where molten aluminium is around.

Don't let me scare you off from doing it, just use common sense precautions.

Regards
Ray

kraits
21st Sep 2011, 12:28 AM
your not wrong about it exploding Ray, i had copper pop once when i was pouring it, the boat i had just made to pour it into wasn't wet but slightly darker in colour from cooling it with water 10 minutes earlies, even though there was no visible water present the dampness was enough to make it pop and spray balls of molten copper around my shed.

pjt
21st Sep 2011, 01:58 AM
Any container that can be heated to around 700 deg C allows you to melt it.
However you need good insulation to get things that hot without heating the rest of the town. That kind of insulated container is called a furnace.
Google "melting aluminium" and you'll find all kinds of solutions.
You also need a burner - gas, coke or oil. ELectricity is feasible but more complicated.
You should PM RayG for assistance!

Please don;t melt the gas cyclinder. The day after you do, you will find a use for the heavy wall aluminium pipe between the ends! Just cut them off and melt them if you really must - and put the pipe section in your metals stock.
Joe
Yes, somebody will give you a compressor unit which will go nicely with that motor you have under the bench and all I need now is a reciever, Ahhhh I melted that:doh::p

Pete

welder
21st Sep 2011, 08:47 AM
i was planning on using it as an air receiver but i have a steel oxygen clinders for that job.

eskimo
2nd Oct 2012, 05:23 PM
Now for a safety warning, casting aluminium is potentially more dangerous than casting bronze or copper. The reason for the danger is a bit subtle, aluminium is very reactive, it reacts with air very readily to form aluminium oxide, every piece of aluminium you have ever seen is coated with a thin layer of oxide, when you have molten aluminium, it can't form that protective oxide layer, so it reacts with any oxygen that it can find, if molten aluminium comes in contact with water it's so reactive it will strip the oxygen out out the water (remember water is H2O) leaving hydrogen gas, which in turn will burn ( more likely explode) when it bubbles out of the molten aluminium and combines with the oxygen in the air. (I'ts called a hydrogen explosion)



I did a lot of work at Castalloy, now owned by Harley Davidson over 30yrs or so, and the video we had to watch for OHWS induction really showed what happend in a sleeper walled bunker ..it was about 1.5 square and about 2 meters high fully enclosed on three sides and top and then dirt ...sort of like being cut into the side of a hill

certainly opened my eyes as to what a cup full of molten alloy could do when it came into contact with moisture...the little bunker was destroyed

Chris Parks
2nd Oct 2012, 06:33 PM
It's easy to melt aluminium, try and weld it with oxy acetylene. I guarantee you will melt a heap of it while you are learning!!:U:U

Ueee
2nd Oct 2012, 07:34 PM
Hi Andre,
If you have a piece of nice heavy pipe, say 250 or 300mm dia, same sort of length, build a charcoal fire as Ray said and plonk the pipe on its end on top. The bottom edges of the pipe may suffer but you will contain the heat. Just take some more pipe or heavy RHS and weld a cap on the bottom and some lifting rings on the top and side and you have a crucible. Stainless pots are ok, but as they are so thin you will eventually burn a hole through them and lose your ally into the fire.
Make yourself a "sandpit" and put indentaions in it the size of your wanted ingots and pour into the sand.....just don't use a plastic bucket to hold the sand.....guess how i know that?