John Greene of FL Sales Inc. talks with us about various methods used to cast metal in foundries.
About this segment of Blackbird TV
Recorded: September 28, 2020
Published: July 13, 2021
Let’s talk about the differences between shell, no-bake, because those are those are really fundamental differences in how things are done. Not so much fundamental. The most widely recognized is what’s called green sand. Green sand, I’ve never seen green sand. Usually it’s full of algae when it’s green and I’m at the beach. What what is green sand? Well, they call it green sand molding. And basically you’re taking silica sand. You’re adding clay and you’re adding water. OK. It never looks green. Don’t ask my why they named it that. Whose idea was that? It confuses me. It becomes black. When you pour metal into it. So don’t ask me. Maybe they named it after me. I don’t know. John Greene says green sand. You should get a… You should get paid for that. There you go. So that’s the most commonly used, basically silica sand, water and clay or bentonite, as they call it, shell sand. Basically, you’re taking a virgin sand. You’re coating it with a resin in a in a resin coating plant. It can either be done in-house or bought outside. Usually it’s bought outside and brought in. What you do is you put the two molds together. They actually call this shell molding, which is shell sand. And you heat that sand with the resin, and it cures. And that’s how it sticks together. So it doesn’t collapse on itself. Correct. All right. So that’s shell. Then you have no-bake and there’s a lot of different binders and different processes, but basically you’re taking, again, a resin coated sand of some sort and you’re forming it into a mold. And either A is using a gas like CO2 is one of a process where you can purge it with CO2 and it hardens the mold automatically or the sand has a resident binder that mixed together over a certain amount of time, whether it be two or three minutes or 15 minutes, that’ll automatically harden. And that’s called no-bake mold. There’s also investment casting where you take a wax impression and you put ceramic coatings over the wax impression multiple times. You coat it with sand, you put a liquid, coat it was sand, put a liquid, go back and forth, then you melt the wax out and that creates your mold impression inside. A lot of that is used for aerospace. Golf. Highly intricate parts are done a lot in investment. There’s also a method called lost foam and lost foam is where you take sand and either use a plastic or a a just a vacuum. And what you do is you you put your impression in and create a vacuum or suction that holds the sand in, take the impression out and you pour your molten metal right into that. The advantage of that is you get a good surface and that sand can be reused again. Because it doesn’t have any binders in it. Right. It doesn’t have to be reclaimed. Interesting stuff. Foundry work, John Greene, FL Sales, Cleveland, thanks for your time. Thanks, David.