Aluminum sand casting for Chenery Gnome Rotary

[albd5a]

The remaining aluminum needs to be poured out of the crucible into ingot molds.
I use steel ingot molds that are made from steel angle iron, with the end caps welded on at an angle to allow the ingot to release.
The ingot molds need to be preheated to perhaps 500 F before you pour into them.
I generally place the ingot molds in the exhaust stream of the furnace.
If you don't preheat the ingot molds, the slight amount of moisture on the surface can flash and pop the molten aluminum back into your face.

If you leave metal in the crucible, it could crack the crucible as it cools/contracts, and then expands when heated.
Some folks scrape out their crucible after a pour, but I have never done that, and never had any crucible problems.
All of my crucibles after the first off-brand one have been Morgan Salamander-Super clay graphite; one for each metal type to avoid contamination.

Here is a video of what can happen if the ingot mold is not preheated to about 500 F.
Needless to say, never wear synthetic clothes or shoes when melting/pouring iron, since it will melt onto your skin.

I had this exact thing occur with iron, and I had preheated my ingot molds, but not to 500 F.
I got some 3rd degree burns when some iron splatter ran down inside my gloves.
You want burn photos? I got burn photos.

What is the best type of fire extinguisher to use?

 

[Fidlstyks]

I do not want a cracked crucible!!! So, thank you. How long can a graphite crucible be used for, about 8 kg crucible?

I do not want a cracked crucible!!! So, thank you. How long can a graphite crucible be used for, about 8 kg crucible?

I use no 16 Clay Graphite crucibles for iron casting, they pour around 400# before getting thin, at around 42# per pour.
I use longer lasting Carbon bonded Silicon Carbide for aluminum abd brass. They last alot longer.
What can happen to them is the drawing of moisture. If you even leave one out in the dew of night, they can split off from steam. One must seek dryout advise from a manufacturer.

 

[albd5a]

I use no 16 Clay Graphite crucibles for iron casting, they pour around 400# before getting thin, at around 42# per pour.
I use longer lasting Carbon bonded Silicon Carbide for aluminum abd brass. They last alot longer.
What can happen to them is the drawing of moisture. If you even leave one out in the dew of night, they can split off from steam. One must seek dryout advise from a manufacturer.

If I am understanding this correctly, that would be 10 pours at the most. And that’s the problem, they get thin?

 

[Fidlstyks]

If I am understanding this correctly, that would be 10 pores at the most. And that’s the problem, they get thin?

For running 2,900°< aluminum they can last alot longer. Yes when they melt away and the top ring meltsbrakes out. Time for a new one. One can see it.

 

[Fidlstyks]

Looking at my flasks, half are only 3-1/2" tall on cope or drag side.
For your little piece, that would not be the problem.
The first pour looked like either hot sink, never filled from too cold or steam. But steam usully has other signs. Like it wanted to fill over the pock mark, with a real thin skim.

 

[GreenTwin]

I do not want a cracked crucible!!! So, thank you. How long can a graphite crucible be used for, about 8 kg crucible?

have been using my Morgan Salamander Supers for over 10 years, and they are all in good condition.
I have never scraped one out.
The aluminum film that remains in them after you pour the molten metal out is very thin and flexible.

 

[GreenTwin]

If I am understanding this correctly, that would be 10 pores at the most. And that’s the problem, they get thin?

A good crucible brand will last almost indefinitely at aluminum temperatures.

At brass/bronze/iron temperatures, you may get 30-40 melts on a high quality crucible.

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