Got a chance tonight to do one of the coolest things I think I have ever done. As part of joining Tau Beta Pi, a national Engineering Honor Society, we spent a few hours today at the UW-Madison Foundry casting bronze bents. A bent is the symbol of Tau Beta Pi (see the upper left-hand corner of their homepage). The foundry was very cool. I don’t remember the year that it was founded, but it’s been around since long before there was a Materials Science & Engineering program. We spent much of the afternoon packing an oily sand into molds around the forms of our bents, and then extracting the form to leave a hole for the bronze. I understand, in a very vague, naive way, why blacksmiths are as strong as they are. Just smashing sand into a metal frame was pretty tiring on the arms. By the end of the night though, the main event. We melted down a bunch of old bronze (partly flawed castings from previous years, partly bronze scraps) in this big induction furnace thing, which resulted in boiling bronze that glowed very brightly yellow. Definitely something you should see sometime: molten metal. To be perfectly accurate, I shouldn’t say “we” melted down the bronze. One of the three (or so) grad students who run the foundry was doing the actual melting, though the VP of TBP helped him with pouring the metal into the molds.
Here, roughly is the scene:
On a worn brick area in the middle of the shop floor there are 4 metal frames sitting, full of compressed oily black sand. In the middle of the sand are gaps in the shape of TBP bents. To reach those gaps with bronze there is a hole that we cut out, as well as a bit of a funnel-like lip that we carved into the upper surface of the black sand. At the far side of the room, a giant circular heating/furnace element has just been lifted off of a crucible containing molten bronze. Two men in space suits (or close enough… bright aluminum heat suits including helmet/face shield/cape, jacket, pants, and boots) grab the crucible with a distinctly medieval-looking clamp device, and carry it to another yoke with a single handle on one end, and two on the other. They then lift the second yoke, with the brightly glowing crucible several feet from each of them in the middle, and begin pouring bronze into the molds. The bronze flows out like water, at first, bright orange with flashes of even brighter yellow, and then bubbles up when it has filled the mold and oozes just like you would expect lava to once it has begun to cool. After filling our 4 molds, the remainder of the molten bronze is dumped into an iron frame to cool & be stored, and the overflow from this looks just like Hollywood magma… bright orange glowing metal dripping slowly until it cools.
Definitely an awesome experience; it felt like a cross between the middle ages (or even 2000 BC, which is apparently when bronze was discovered) and landing on the moon, what with the spacesuits and all.