Metal Casting Zone

Hello there,

I've succeeded in melting aluminium in my home furnace, and casting ingots into sand, which is very exciting! However, whilst I'm generally pleased with the ingot's shape etc, the surface of the finished ingot is often quite rough and has small indentations. How do I get the ingots to cast with a very smooth, mirror like surface?

Thanks!

Andrew.

Aluminum shrinks and oxidizes as it cools. It will pick up the sand grain pattern in the finish. The best a backyarder can hope for is a smooth surface so it can be polished to a decent finish. Finer sand or a metal mold will help and high Silicon Aluminum alloy like pistons or intake manifolds will give a better finish.

a smooth finish "straight from the pot" is hard to obtain . most sand casting uses a pattern which is oversized to allow for machining which removes all the marks. we strive for as smooth as finish as possible to lessen the task of machining. using metal molds such as industry uses will produce a almost perfect finish but metal molds cost thousands$$$$$$ "a sand castable pattern" is very expensive as well and im amused at times when i see a cnc peice being used as a pattern when the piece doesnt allow for machining.!!so it sounds like you are ready to start making something???please share! we are a bunch of doers here and appreciate the effort involved and when a member doesnt post for a while we know they are casting and way too tired too talk!

I use a piece of 2inch steel channel for an ingot mold. After you polish it up the ingots come out ok.

I'm not really following why you want shiney ingots? Well, I like shiney stuff too.
Are you thinking if you can't get a nice shiney looking ingot then how will you get a shiney part?
It takes a lot more buffing that I thought to get Aluminum to shine up like a mirror.
But, my castings have been rough to start.

oops did you mean to post this in the other thread on micro torches.?? chefs use these torches all the time to seal meat, scorch the top of the microwave pie .

Sorry XL, I moved it to the right thread.

I'm after shiny ingots because I am trying to make nice paperweights; I don't have machining facilities at the moment. I'm very pleased with the size, shape and weight of the cast, but the overall finish lets it down a bit.

Thanks for the tips though; I'll try using a metal mould next time!

Andrew.

You don't have to have a milling machine, just some fine sand paper, a buffing wheel on a drill and some buffing compound. Harbor frieght has Aluminum buffing compound for a couple bucks. Also whole buffing outfits.

When pouring Al into a metal (steel/Iron) mold, does it matter if the mold is cold. I mean, will the Al explode or is it dangerous?