Flux

Where the metal submits. Metallurgy to Melt point.
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Harry
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Re: Flux

Post by Harry »

Mike that comes from my foundry supplier IFSCO. I get it in 50 lbs bags. Same with the Degass tablets and everything else I use it comes in bulk just the way a large foundry would receive it. One of the amazing things is how small the plumbago bag is compared to the non-silica parting bag, both at 50 lbs but the plumbago bag is about 1/4 the size.

I keep everything stored in a plastic trash bags inside of barrels left over that sand had come in.
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barryjyoung
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Re: Flux

Post by barryjyoung »

WOW:
What an education in fluxing. I cannot wait to start casting.

Question 1: Do grain modifiers enlarge the grain size of the aluminum That would make it machine better.?

Question 1.5: By "Machine better" what specifically are you referring to? Gumminess?

Question 2: Can you de-gas and flux at the same time or is there some reason most people do it in two steps?

Question 3 (the dumb question): Degassing decreases porosity or is it to get rid of Nitrogen thereby making the castings stronger?

Question 4: Why do you use paper rather than aluminum foil to bundle your fluxes?

Question 5: Does the amount of flux you use vary with the size of the crucible? I mean ALL of our crucibles are pretty small, do you vary your charge based on crucible size?

Thank you oh learned ones.

Barry
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Harry
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Re: Flux

Post by Harry »

Grain modifiers would be like strontium and tibor like foundryjoe was selling on eBay. Flux is to gather the dross making it easy to remove from the melt and to release metal from it reducing waste.

Degassing is for removing absorbed gas that will cause porosity in the part. For parts that are not machined or polished this really isnt needed if you use good clean metal and keep the atmosphere right. I have found lately since I am now starting to machine parts that I want to try and remove some of the very small porosity I have. My understanding is that aluminum absorbs hydrogen so you want a lean atmosphere so as not to provide it in the first place. Your degasser is plunged into the the bottom of the crucible so the bubbles go all through the melt. Dont have a clue as to any difference in using foil or paper to make up a charge.

Fluxing is done last as the last thing right before pouring. The flux is applied to the top of the melt, I use a piece of 3" thin pipe held over the crucible and just drop it in, the pipe keep it from blowing away. I just use a couple tbl spoons in a #10 crucible.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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4cylndrfury
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Re: Flux

Post by 4cylndrfury »

I have read recently that in order for lite salt (sodium chloride -NaCl, and potassium chloride - KCl)to be most effective as a flux, you must melt the 2 together first, and then cast the molten salt into tablets. Salt melts at pretty low temps, not tough for a caster in terms of energy needed. Im just not sure what you would melt them in...I mean, salt will flux steel pretty badly, but would also absorb into most ceramics, so most of our crucibles are out. You also wouldnt want to cast the salt into sand molds, it will soak right in (I think?), and it will corrode steel pretty fast too. Anyone have any ideas?
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Harry
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Re: Flux

Post by Harry »

Yes you need to first melt the two salts together. That is pretty cool in and of itself, I mean melting salt :twisted: 8-)

I really dont like the salt flux though. When you put it in on top of the melt it will remelt and flow across the top of the metal soaking into a SiC crucible if it reaches the edges. The flux I use does not melt, it burns like some kind of reaction and stays dry, it also makes the dross very dry and crumbly.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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Rocco
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Re: Flux

Post by Rocco »

Hey Harry, have you got an MSDS or technical datasheet for your flux? I'd be interested to know what's in it.
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Harry
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Re: Flux

Post by Harry »

I have been told it is the same stuff that BCS sells rocco and here is the msds. I am going to check again with my supplier on that because that says it melts under 1000* F and I have never seen this melt, like I said it seems to react with the alumina and and the whole mess glows (burns?) very hot.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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Rocco
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Re: Flux

Post by Rocco »

Interesting according to that, it's a salt flux with a few added components. On a somewhat related note, I was just looking at some of the other MSDS's on the BCS website and discovered something interesting, the address on the MSDS for their degassing tablets is close to me, in fact, I drove within a few hundred yards of it a few hours ago, I wonder how receptive they would be to a guy walking in off the street and asking to buy a few small samples.
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4cylndrfury
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Re: Flux

Post by 4cylndrfury »

Rocco, let us know if they are open to outsiders poking around. I think there are a lot of us who would be very interested in what you find out!
"Simplicity is the ultimate sophistication"
-Leonardo Di Vinci

"The future's uncertain and the end is always near...."
-Jim Morrison
Rocco
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Re: Flux

Post by Rocco »

I'm not making any promises but maybe I'll do that some day.
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