Aluminum Foundry

[trently]

Hi all, Another source of good scrap to melt is an auto repair shop as there is a lot of aluminum parts that gets replaced and thrown out. the best is pistons but suspension components are good to

 

[MRA]

You're really going for it, melting swarf! I seem to collect more ali scrap than I need, partly I suppose due to where I work - I've used a lot of extrusions (doors / window frames) which people say are not the best, but I've had OK results. I have some pistons and a load of what is apparently cast alloy, saved up for something that 'matters'. You know how it is.

A recycler I know collects beer cans from an alcoholic neighbour, the painted walls of which he cuts off (!!) to save for roof shingles for a projected shed. We had a go yesterday at compressing 'ends' in his press, with the idea of melting with less surface area / oxidation / dross. He has high hundreds, perhaps thousands. I don't know how I feel about a shed which is a monument to the tenacity of someone else's liver.

 

[Rndmann9]

Lol. When I was in college one of the local homeless but industrious guys used to come by my fraternity house and collect all the beer cans in a grocery cart...one day he showed up in a brand new f150 truck. I often wondered how much money we literally tossed and he gave me the assurance at that moment it was plenty. The swarf is just a reserve. I've got a fair amount of scrap so when I'm done with a pour and don't quite have enough for muffins I'll toss a couple bricks of swarf in while it's hot and make a couple muffins for the next one. If you leave enough melt to dunk them they don't create a ton of dross. More than I'd like but better than throwing out all that aluminum potential.

 

[Wizard69]

Wow, nice castings for a first effort! Starting with swarf doesnt make the process easy.

By the way most of my casting experience is from working in a zinc die cast foundry just out of high school. Metal contamination can raise hell with your resultant alloys, id suggest keeping a close eye on what goes in the pot.

In a die cast zinc plant steel falling into a pot {pot metal}of zinc is a bad thing. The way the engineer explained it to me is that the steel in contact with the molten zinc and cast iron creates an acid that eats through the cast iron. Im not going to debate if it is an acid per say but you can clearly see how the steel eats through the cast iron when the pot is drained. I know this pulls the thread off track but i was amazed as a young guy to see how this happened. I found it especially odd because cast iron and steel are so closely related.

 

[Cogsy]

In a die cast zinc plant steel falling into a pot {pot metal}of zinc is a bad thing. The way the engineer explained it to me is that the steel in contact with the molten zinc and cast iron creates an acid that eats through the cast iron. Im not going to debate if it is an acid per say but you can clearly see how the steel eats through the cast iron when the pot is drained. I know this pulls the thread off track but i was amazed as a young guy to see how this happened. I found it especially odd because cast iron and steel are so closely related.

Long ago I worked as a hot-dip galvaniser, which is primarily molten zinc with some small amounts of nickel, lead and aluminium. Our pot (called a kettle in galvanising) was steel and large amounts of steel and cast iron was lost to the bottom of the kettle to be fished out at the next dross removal shift (oh how I hated those shifts but we only did it every few months). Interestingly, we were told that copper in the kettle was a very bad thing and if we tossed in a 1 or 2 cent coin (which were copper back then) they would eat their way through the bottom of the kettle. Sounds like much the same as you were told but obviously different metals - and it's very likely that there was no truth to either story. Some metals don't play well (Gallium and Aluminium for instance) but steel/zinc/copper/cast iron work well together. I think those 'old guys' were pulling our collective legs and we were gullible enough to believe them.

 

[CFLBob]

Do you ever put some sort of flux in while you're melting the aluminum swarf? I've melted silver and we always throw in some borax.

 

[Rndmann9]

Do you ever put some sort of flux in while you're melting the aluminum swarf? I've melted silver and we always throw in some borax.

Light salt ( potassium chloride & sodium chloride. Degass the aluminum with calcium carbonate (washing powder) not to be confused with calcium bicarbonate (baking powder).

 

[Rndmann9]

Correction to earlier statement. Sodium Carbonate not Calcium

 

[CFLBob]

Thanks. I'm looking for plans for a foundry I can build. Lots to choose from.

I already have an acetylene/air torch.

 

[SmithDoor]

I used propane and or fuel oil #2 aka diesil fuel
The old type furnace unit works great just flip of switch and it is running

Thanks. I'm looking for plans for a foundry I can build. Lots to choose from.

I already have an acetylene/air torch.

 

[machinejack]

For non porous castings in aluminum I have always used pool shock for a flux/degasser . A reil type propane burner in a 12" piece of pipe lined with 1" of kaowool. In a home made sch 80 pipe crucible. Been doing this for a few years. I started out using a green sand made with bentonite clay but have since graduated to PetroBond. Now 66 years old "I'm retired from the clock but not from life".

 

[CFLBob]

Isn't pool shock liquid chlorine? I think I've heard of some sort of powder, but the only pool shock I've seen used was liquid chlorine solution.

 

[machinejack]

I only know that before I started using it I had porosity in my castings. I read somewhere about using pool shock to get the hydrogen gas out. I use a forked rod and roll a little bit of the shock in aluminum foil and as soon as I take the melt out of the furnace I plung the rod to the bottom of the crucible slowly stir the pool shock in. It bubbles for a few seconds then I skim off the dross. Don't know the chemistry but it works for me. Stay up wind of use a respirator as chlorine gas is produced.

 

[CFLBob]

Although I've never had a builtin pool, one of my first jobs was working maintenance in a condo with big pools. Pool shock was like the liquid chlorine we dumped in to chlorinate the pool, only supposed to be way more concentrated. Looking around on Google before I saw what looked like some sort of crystals or powder that gets dumped into the water. Do you use the liquid or solid?

 

[machinejack]

You need the powder form. Ace Hardware sells it HTH brand. Most big box stores carry it under different names.

 

[nel2lar]

Oil will burn off. The steel will do as you said and either sink or float up as dross. Ke” View attachment 102755

Rndmann9
The question of melting all your chips is a very good one. What I do when I gather up the chips I place them in a cut open soda or pop can, then I bend over the edges and crush the can down as much as I can. When I melt my other metal and the crucible is molten I will put the can of chips in and hold down until melt is started. I have a lot of chip melt under my belt and it is something that works and the best way to get the biggest bang for what you are doing.
Nelson

 

[Wizard69]

The issue with the loss steel was very interesting to me as you could actially see how a dropped bolt or whatever would eat though the pot when it was drained. In a couple of cases you could see the thread imprint in the cast iron.

Honestly when I left that plant after about 2 and a half years of working there it was the happiest day of my life. Conditions where bad and most of the people employed there where not the types you could trust with being safe. I lost track of how many times I drove into the place to find out that an ambulance had been called yet again to take somebody to the hospital. Now I work at a place where they go overboard with safety, thank fully the only time an ambulance gets called is for someone having a heart attack. Not that that is a good thing mind you but none of them have been job related.

Long ago I worked as a hot-dip galvaniser, which is primarily molten zinc with some small amounts of nickel, lead and aluminium. Our pot (called a kettle in galvanising) was steel and large amounts of steel and cast iron was lost to the bottom of the kettle to be fished out at the next dross removal shift (oh how I hated those shifts but we only did it every few months). Interestingly, we were told that copper in the kettle was a very bad thing and if we tossed in a 1 or 2 cent coin (which were copper back then) they would eat their way through the bottom of the kettle. Sounds like much the same as you were told but obviously different metals - and it's very likely that there was no truth to either story. Some metals don't play well (Gallium and Aluminium for instance) but steel/zinc/copper/cast iron work well together. I think those 'old guys' were pulling our collective legs and we were gullible enough to believe them.

 

[Cogsy]

Honestly when I left that plant after about 2 and a half years of working there it was the happiest day of my life. Conditions where bad and most of the people employed there where not the types you could trust with being safe. I lost track of how many times I drove into the place to find out that an ambulance had been called yet again to take somebody to the hospital.

Another similarity of the jobs, when I began working at the galvanisers I was replacing a 20 year old guy sent to the hospital with 3rd degree burns to 75% of his body (never found out if he survived) yet being young and stupid I didn't think too much about it. While I was there for only around a year and a half, there were many accidents and I had to (literally) run for my life on 2 occasions. I got out with only 1 serious burn and a smashed foot but many close calls. While I was employed we only had 1 fatality at the plant but I don't know how it wasn't more. It's so much nicer doing what I do now...

 

[stuartblack]

Dont melt Aluminium in a steel crucible the Aluminium eats it, there are two groups on face book devoted to metal casting. Any questions you have, will have been answered before. Graphite crucibles are cheep.

 

[TonyM]

Dont melt Aluminium in a steel crucible the Aluminium eats it. Graphite crucibles are cheep.

Although what you say is true, the reaction with steel is so slow that it is not overly important if the crucible has a decent wall section.