Casting aluminum in ABS

thingiverse

Aluminum cast in ABS mold. Link to an earlier casting project, with pewter, zinc and lead.http://www.thingiverse.com/thing:286521 Instructions I've been doing some more metal casting in ABS molds lately, and on the spur of the moment, decided to try aluminum. I long ago deleted this mold's STL files, and can't post them but they are not important. It's a very simple mold. There's a tall core which forms the inside of the casting and a 2-sided box that forms the outer diameter. The sprue is just a long square hole, feeding from the bottom up. I never intended to use this print as a mold for metal casting. It is a terrible design for the purpose. But it did have thick sections and that's what I was curious about. Aluminum is not at all fluid compared to some alloys and it won't flow and fill thin sections by gravity alone. But thick parts contain so much heat I was not anticipating any sort of success. Aluminum (an unknown alloy) was poured at 1250F. That's hotter than it needed to be, but I wanted to see what would happen. Among other defects due to a high temperature, the surface is rough and might be much better if it were poured cooler. However, it may not be possible since the plastic mold virtually evaporates, and gases may always cause bubbles, roughness and various surface defects. The mold inside diameter was designed to be 1 inch. The casting ID is 0.99 inch. Mold's outer dia was 1.25", and the casting result was 1.215". So it shrunk quite a bit for a small casting. But it did come out nice and round. There was much smoke but no flames. A greyish, stinking smoke but with none of the black soot from setting ABS on fire. I'd estimate about 100+ cigarettes might produce the same cloud volume. After a few moments the very hot, very soft mold was dumped into a bucket of water. It steamed and sizzled for a minute. This was an experiment to explore materials and possibilities. Results are completely unpredictable and therefore it's very dangerous. Do not try this. Don't even think about metal casting unless you have the proper equipment, and know and follow all the safety rules and requirements. One false move and it's ambulances, cops and / or fire engines. PS The ornament STL file uses Imperial measurements. If metric print software imports it as a tiny 2 mm diameter, which is likely, scale it up by a factor of 25.4. Or as big as you like i guess....