Metalcasting

Melting the Metal

The furnace is together, and the blower is blowing! Lots of sparks shot out of it, but they didn't really show up in the picture.

The crucible, loaded with aluminum scraps, in the furnace!

Fire in the hole! The reflective sheeting burning off the aluminum scraps. I was afraid there'd be tons of obnoxious smoke, but it all burned very cleanly.

Another view. You can see glowing spots on the side of the upper can, but the bottom can is not even discolored.

Hot, hot, hot! The crucible is glowing red. The aluminum has softened to the point where it packed down. (What is left of the reflective sheeting is kind of greenish.) Just a few minutes after I took this picture, it was molten! A nice crucible-full of shiny metal that I forgot to take a picture of. I grabbed the crucible with my whiz-bang fancy crucible tongs...

...and dropped it on the ground. What a putz. Here is the spill, after I picked up the crucible and taught the kids some new words. The crucible was lying between the mold and the furnace, pointed away from me; you can just barely make out a black smudge on the gravel where it was. Good thing I had that spatter guard...

Try, try, try again. I returned the crucible to the furnace and reloaded it. After it melted, I poured - sorry, I couldn't figure out how to take pics and pour at the same time and I wasn't about to let the kids off the back porch to play cameraman.

I poured the mold, and was surprised how fast it filled up. I figured I'd poured too cold and the mold had only partly filled.

Then I poured what was left into the ingot mold. As you can see, I kind of missed the hole.

I turned everything off and let it cool - but after about ten minutes, I poked the crud in the crucible with a 1/4" iron rod, and found it was still molten! So... I reloaded the crucible and turned the blower back on! After it all melted down and I skimmed it, I was left with a nice pot of molten aluminum! And this time I rememberd to take a picture of it. Rather than try to whip up another mold, I just covered the ingot with a layer of sand and poured the aluminum on top of it.

Another view, just before the third pour. You can see the first "pour" (when I dropped the crucible) on the ground against the bricks.

Shaking Out the Mold

A shot of the mold. It's been about a half hour since I poured it, and it's still too hot to touch.

But I couldn't wait. I pulled off the cope and found, to my delight, that the mold had filled after all!

Close-up of the casting, still in the mold. Not the best surface quality.

Dumping the cope into the ingot mold.

Tada! There it is!

The EMTs (Emergency Medical Toddlers) who were standing by to call an ambulance in case I screwed up, showing off my screw up.

The final result! The surface quality is weird; on the sprue, it's so smooth it's almost shiny, but it's pretty rough on the pattern. I think this is a result of the sprue being rammed much harder than the rest of the mold. Note the shrinkage in the upper surface.

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© 2003 W. E. Johns