Home made cast Aluminium

I am sure that many of the people arguing against this have not done much aluminium casting. Once you have a furnace it is quick and easy. As a raw material I usually use car wheels which are a good quality source,

Inclusions? In over ten years of casting I have never had a problem. I never degass, but a few tiny bubbles in the casting do not matter, I would not use it for a critical part in my car.

But what a saving in cost and time! If I want to make a part that requires a large chunk of aluminium I can be machining it the same day for just the cost of the gas. I scrounge the wheels.

Would you use a car engine cylinder head Norman and how much time you reckon it takes to melt say a kg of alu?

I'm very much tempted by the idea, aluminium suppliers are few, costs are high and you dont get much choice here. I mostly order the material I need off uk sellers (not linking any ) but shipping is a killer.

Have all the material to build a 2kw electric heat treat oven, it should be good for up to 1000°C so it could melt aluminium in theory. At 0.16€ per kwh it could work out as good solution.

I've done lots of home ali casting, usually on the 'lost foam' principle using hard insulating foam (open cell packing foam is useless). The casting part is relatively easy, if you take care - (don't wear sandals ). I was advised to heat until it was thoroughly molten, scrape off as much dross as possible, then leave it to stand for a few moments before pouring to allow air to rise and disperse. This has worked well for me, and I have cast many bits and pieces, for example for a sanding disk machine, and for electric motor mounts. I have experimented with sand casting, but found it virtually impossible to get the various additives needed, despite many self-proclaimed experts telling me to use cat litter and so on.

As well as parts, I also cast slugs of ali to use for turning - usually OK, but do expect to find some blowholes sometimes, or very small pin-holes in the metal. There are many 'folk-lore' stories of what can be used as flux to help prevent this - most never seem to work, so the best way is to try it yourself. If it doesn't work, you can always remelt the ali and try again.

I used all sorts of stuff as raw material - cans are useless, they will burn to dross. Try old car engine bits, such as cylinder heads or pistons. My scrapyard lets me have them just for the scrap-metal weight.

Biggest 'don't' is don't spill the hot metal - it spits like hell on earth or cement - work on a sandbed is best.

There are many websites providing info, such as furnace builds and burners - mine is a stainless steel bread bin lined with a mix of fire-cement and some clay I found - works fine. The burner is home made according to J Reils ideas, and works equally well on Propane or (more slowly) on Butane (Propane is hard to get where I live).

I have been melting aluminium and casting for a few years. It is relatively easy to make a propane gas fired furnace to melt aluminium from simple readily available materials. Old aluminium castings are the best source of material but I frequently mix old aluminium extrusions into a melt and this does not seem to be too detrimental. I usually make lost foam castings and these can have complex shapes. For stock for machining I usually cast in old tin cans for the larger diameters (50 mm -75 mm). The can after casting is simply cut and peeled off the solidified aluminium when cold. Smaller diameters are just cast in green sand using a bar of the right diameter as the pattern. The cast material usually machines very well. I once cast a rod from melted drinks cans but this was very gummy and it did not machine well.

To get a good clean casting without inclusions or void it is important to use a flux. I use a product called LoSalt which ios mixture of sodium and potassium chlorides as flux. This is readily available in supermarkets as it intended for people that need low salt diets. I desert spoonful of this in a one litre melt of aluminium brings all the dross up to the surface where it can be readily scraped of usinf a spoon.

I wrote an article that was published in MEW some years ago describing making the furnace and burner and describing some of the casting techniques. There is also some information on my website covering this, see:

**LINK**

ChrisB, trying to melt a whole cylinder head would take a long time. It is best to reduce it down to small pieces. An angle grinder is slow and will not cut big pieces. I have tried cutting large parts, wheels, with an angle grinder and used a large hammer on partly cut pieces. It is hard work.

Due to changing domestic circumstances I have had to use different approaches. When I first started casting I used to build a large wood bonfire and stack the wheels on top, as it reached melting temperature the aluminium would run out of the bottom of the fire and if you got to it before it cooled too much you could break it into small pieces with a hammer. This produced dirty material which I had to remelt in my furnace to cast clean ingots. This cost me nothing as I was using peat as fuel which I had obtained free.

When I had to start paying for fuel I used a different approach, I collected as much scrap wood as I could and built a fire in an oil drum that had a hole in the bottom and was perched on bricks. As the aluminium melted I placed a loaf tin under the hole  to catch the molten metal and produced 3 kilo ingots. Too big but they were clean,

Nowadays I live in a home closely surrounded by neighbours, I collect small pieces of aluminium that will fit into my crucible. I find it very restrictive.

As for casting blocks for machining I use bean cans, old tobacco tins or anything that is near to the size that I need. I do open topped castings, I am not looking for precision. Yes, it takes longer to machine it to size but hobby time is free.

Edited By norman valentine on 25/08/2020 19:19:02

That's only really true if your hobby is making swarf. If you actually want parts, whatever they might be for, producing them is just a time consuming step.

The rest of the band didn't care how I made the lower bolt

to reattach this

into the bell. I would much rather the job had taken less than the 2.5 hours it did.

Nicholas, what you are talking about is very different from what I was saying, If I want parts for a particular job of course I will make patterns that will produce a part that needs minimal machining. If I need a part such as the raising block for my toolpost on my lathe, I will cast it in a tobacco tin and save myself quite a lot of money. No my hobby is not producing swarf and your sarcasm is not appreciated.

Hi Norman, no wouldn't attempt to melt a whole head (would need one hell of a furnace!) I'd bandsaw pieces off and melt say a kilo, should be managable. Would like to know if an electric oven (not a household one) would be up to the job, in theory it should as it can reach the alu melting temp and beyond. My idea would be to melt the alloy in a steel form and leave it to cool slowly in the oven...might be a couple of years from now to see the result given the slow pace of my projects!

There is a guy on Traction talk who has also written in ME who uses a couple of electric ovens for aluminium and bronze casting so should be upto the job. Although it mostly shows the patterns this album of some of his work does show a couple of the castings too

Edited By JasonB on 26/08/2020 07:31:37

Last two posts about CoC moved to here to keep this one about casting.

After a few conversations with Rob i found out the pearlite is just the stuff you put in pot plants and is mixed into a sand cement mix to line the furnace . I reckon if you scavenged around for an old lpg bottle you could make a furnace for $20-30 bucks at most. You would get a decent amount of aluminium from just one car rim and if you can scavenge one for free well you're in the box seat then !

Hi, yes I heard about perlite - I was going that route initially, perlite mixed with liquid glass (sodium silicate) but gave up on the gas type furnace, mainly fearing a mishap with gas in my workshop which happens to be the basement of my house!

I then changed my mind to build an electric oven, I have all I need but it's still in the bottom of the to do list. For insulation I got aeriated concrete blocks, which should work well and are relatively cheap compared to insulation blocks. In theory temps of 1100'C could be attained, and as Jason mentioned there's a chap who's been doing this in an electric oven, there's hope it could work. Not that I'm trying it out any time soon.

Portland cement may not be the most long-lived material for a furnace. Cement gives up the ghost at temperatures well below 1000 Celsius. Concrete analysis often relies on heating at 900 degrees to break down the item under analysis.

Home made furnace linings are not a good idea, they break down very quickly. it's much better to use ceramic fibre blanket which is available from pottery suppliers or Artisan Foundry. You can get a coating which you apply to the surface. This is a whole lot better insulator.

Agreed, portland cement will not be up to the job as you say, what I intend to use tho is slightly different. It's not homemade material, I bought these bricks from a construction material supplier. Apparently it's good for 1200'C, the brand which makes them is Ytong. For added surface heat resistance I'm coating the internal surfaces with a mix of aluminium oxide and liquid glass. That's the plan at least. I tested a small piece of brick in a direct flame till it glowed yellow, the material did not degrade but I noted some shrinkage.

Those Ytong blocks are really no different to Thermalite/Celcon type aerated blocks and won't give much in the way of insulation in a furnace, all so as they are made by a reaction between the gypsum in portland cement and aluminium powder which causes the bubbles you are back to the issues mentioned above about ordinary cement.

.

I had never heard of YTONG, Chris ... but that was clearly my loss

Impressive range of products: **LINK**

http://www.ytong.gr/index.php?option=com_content&view=article&id=47&Itemid=27&lang=en

MichaelG.

.

Edit: Contradicted by Jason before I had even posted 

... the man must be psychic !!

Edited By Michael Gilligan on 26/08/2020 18:30:31

Researching these bricks before I bought them I'm sure I had seen somewhere videos of it being tested, one side heat being applied with an oxyacetylene torch and the a hand on the other side of the brick. And there was another gentleman who used it in a furnace with temperature of up to 1300'C. I hope they are right!!

I'm not saying it's better than insulation brick, but it could be a cheaper alternative, especially for me as the only way of getting insulating brick is to import it, and believe me, it's expensive!

High alumina cement is better at high temperatures. Last time I needed any it was available at my local builders' merchant at about double the cost of Portland cement. Mixes well with Perlite...

I think the unit Rob made had a steel liner which eventually burnt away and yes the pearlite cement mix is degrading but he only uses it every so often - probably when he runs out of aluminium bar so he fires it up to build up his stock . If i were going to do a lot of casting i would use the proper stuff but i’m really only likely to use this system once or twice a year at most and i do like the idea that i can make a simple furnace out of junk and cheap materials that i can get from my local hardware store !