Re: Cupola Furnace


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Posted by bpfink on July 04, 19100 at 08:20:38:

In Reply to: Re: Cupola Furnace posted by Lyle Landstrom on July 03, 19100 at 10:12:20:

I agree with Lyle that a cupola for aluminum is overkill.

It would melt it all right, but generally the non ferrous metals at the lower melting temperatures have a tendency to want to absorb gases from their new momentary state of liquid being. A cupola will definitely have more heat than you would want, with more air being blown in directly around the metal before you would tap it off. There would not be any easy way to stir, mix, deslag it (more like descum it), or keep any consistency with it at all.

I do on occasion, though, use a thing similar to a cupola to melt aluminum scrap down into smaller puddles, bars, ingots , or units by feeding it into a 2 1/2 times taller steel drum unit with a blower and hot wood fire at the bottom. The reason is to reduce in volume things like rain gutters, aluminum door frames, tangled curly scrap form Wray's discards, anything found on the side of the road or delivered to me by siding contractors, etc. This is NOT poured into a mold though, just reduced for a later re-melt when ready to use it via a crucible melting furnace so I can get a good 90 lb. or so ready together at one time. (That's a #100 crucible size. not sure of the exact weight in it with aluminum).

The quality of the poured metal from scrap is usually of a slightly unknown and risky nature. I try to always do a melt like that with a goodly amount of near pure aluminum so the resulting alloy is still good to look at. Also try to do the melts with scrap cast pieces that may have another way to control the final properties. I would not risk a melt like this on any machine or mechanical parts that required a known set of properties. So far it has always worked out.

Bottom line for controlled results... I would say that melting aluminum in a cupola is a little like ringing a doorbell with a cannonball.


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