As a child of the 1970s, my friends and I played with a LOT of toys that were die-cast. Most of us didn’t know what that meant; we just knew that we had to try REALLY hard to break them. Turns out, the ruggedness of those toys – and their widespread availability to the first crop of Gen-X kids – is directly related to the casting process. Metal casting produces stronger products than welding pieces together, and it’s WAY more cost-effective than machining parts that don’t necessarily need to hold tolerances measured in thousandths of inches.
One of the more popular methods for parts & products like this is called green sand casting. Basically, they add a specific amount of water to the sand so that it’ll hold its shape – that’s why the best sand castles on the beach are made closer to the surf – and make a mold. Then they pour in molten metal, let it cool, remove the cast part, and repeat for as many parts as they need to make. Fun fact: they call it “green sand” because of the moisture content – like “green wood” gets its name because of the sap content – not because of the color (it’s NOT green colored).
Anyway, the mixing process for the sand & water blend is kind of an exact science. Too much water, and the mold won’t hold its shape, and too little will make it brittle. It’s also easier and quicker to mix if the water is sprayed, as opposed to dumping or pouring it in.
The reason I know all this is that I had the pleasure of talking with a caller who runs a specialty casting foundry. They make parts that weigh a couple of ounces, a couple of hundred pounds, and anything in between. They, of course, keep the molds they’ve made for repeat customers, so they’re ready to go when a new order is placed, but they’re also making new molds all the time, and wanted to improve the sand/water mixing process. They didn’t need the extremely fine droplet size of an Air Atomizing Spray Nozzle, nor did they want something whose flow was measured in gallons per hour. They were actually looking for about one gallon per minute from a compact device that could spray a wide round pattern into a rotary drum that looked an awful lot like a small concrete mixer. They chose Model FL1010SS FullStream Cone Nozzle.
As the sand in the mixer turns, the conical spray is evenly, and quickly, is soaked into the sand. This reduced the time it took to get a consistent mixture, and eliminated clumps they’d occasionally get when the water was poured in, which they’d have to break up by hand after stopping the mixer, which saved even more time…and operator frustration!
If you need to spray liquid in a consistent, repeatable manner, EXAIR has an enormous range of flow rates & spray patterns. If you’d like to find out more, give me a call.
Russ Bowman, CCASS
Application Engineer
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