Wife sent me a video of casting large pots from recycled cans.  They seem to have it down to a science.  The sprues are just enough to suck down flat when they chill.  Any ideas on what the moulds might be made of.  Must have a fair bit of preheat in the mould to get the even fill.

 

 

cans are not made from a castable alloy, and there is a lot of dross.  There are much better alloys to use for Aluminum casting,  read more.

True Steve but if you live in a land where the foundry crew wears ONE high heel shoe aluminum cans might be what they have. More than not being a casting alloy it's the anodizing and ink that makes all the dross, a fair % of the exterior of an aluminum can is aluminum oxide and ink. For what they're doing she's doing it right by shoving the can under the surface as quickly as possible to minimize atmospheric oxidization of the can before it melts. Thin had more surface to volume than does the top of the flask so it looses a much higher % to oxides.

The mold looks to be light weight "concrete" or similar and casting that thin they can probably get away with virtually and furnace cement or mortar on the contact surfaces. Heck it could be mortar soaked rags to make the molds. If so it would hardly take any preheat if they get the al temp right and it looks good to me, just a BIT warmer than chunky for thin section.

Speaking of using an extrusion alloy for casting, I don't know I only tried al cans one time and spent more time feeding the pot than casting. We used to melt cans over the camp fire in the field though, did a couple open molds for funsies. Regular casting alloys work better for thin sections I know for sure. 

I haven't heard back from the guy who offered a veritable trove of aluminum for anyone in the club wanting to cast aluminum. He was offering for SALE a whole pickup truck bed full of bagged aluminum cans and one lawn mower engine. The cans weren't even crushed. I'm betting he took them to the recycling center and discovered they don't pay anything for uncrushed al cans.  Insensitive lout that I am I responded that it looked like a dump run to me, call and ask the recycling center what uncrushed or crushed al cans are worth. 

I haven't seen any howls of injured outrage. Maybe the poster decided to just take it to the dump. Nobody's shown interest after the first couple replies before I saw and commented. Of course somebody may have bought it.

Frosty The Lucky.

 

I shred the cans and compress that into 4”wx2”h discs to slow the smelt.. I also mix 1/2 & 1/2 with old aluminum window and door frames even strips of old school bus body Al.  It creates a tolerable cast with sharp edges and few bubbles. Reduces polishing and filler welds needed after the cast and cleanup.

Cars are full of castable aloy, pistons, brackets, manifolds, transmition housings etc. cans and window frames are extrusions unfortunantly not thick enough for use for forging but the thicker bar stock you buy forges well (aluminum horse shoes...) 

Never figured it would be the most efficient way to cast but they do seem to be rather good at what they do.  I've done just enough casting to know there are better starting materials to work with.  At any rate thanks for the insight into the moulds Frosty.

My pleasure Michael it brought back memories of casting aluminum in shop class. We didn't have to pay for aluminum if we brought in good casting stock, transmissions were popular and everywhere. We'd come in early or stay late to bust them up with sledge hammers. Fun times. 

Last time I visited, my Sister has the ash tray I cast for Dad in jr. high on a shelf with some of Dad's things. Dad hadn't smoked in 25+ years when he passed but he had that ash tray on his desk. Frosts don't seem to throw anything away. 

The video was good watching provided you don't take your PPE cues from them. 

Frosty The Lucky.