Graphite crucible breaking down quickly

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Messerbr
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Graphite crucible breaking down quickly

Postby Messerbr » Wed Dec 13, 2017 7:53 pm

So we're working on updating our casting method to use a vacuum machine and a smelter for more controlled temperatures. We're running into an issue of the graphite crucible breaking down rather quickly and I was wondering if anyone else has run into something similar. it seems that we are having some graphite pieces fall into the flask as we pour the metal in. Picture of the crucible is below. I dont have a before and after, but before the latest melt the graphite walls were pretty smooth and this is what it looks like now. The other two we have are a lot worse.
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Chalamba
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Re: Graphite crucible breaking down quickly

Postby Chalamba » Wed Dec 13, 2017 8:31 pm

Poor quality graphite, that is it.
I found a rather good producer from China and I am happy with their quality and price 2kg cruicable is if I remember correctly 18$.
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Messerbr
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Re: Graphite crucible breaking down quickly

Postby Messerbr » Wed Dec 13, 2017 9:07 pm

Do you remember the name of the producer?
Chalamba
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Re: Graphite crucible breaking down quickly

Postby Chalamba » Wed Dec 13, 2017 10:33 pm

Here you are:
Look what I found on AliExpress
http://s.aliexpress.com/BV7vYzyE
rkundla
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Re: Graphite crucible breaking down quickly

Postby rkundla » Thu Dec 14, 2017 1:20 am

I bought a small one to try to make metal shot from my scrap silver and after the first time I fired it with a torch, it started to disintegrate. Bought it on eBay so it isn't top of the line, but it really surprised me.
eg123
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Re: Graphite crucible breaking down quickly

Postby eg123 » Thu Dec 14, 2017 3:04 am

"I bought a small one to try to make metal shot from my scrap silver and after the first time I fired it with a torch, it started to disintegrate."

Looks normal to me.
They are "not" meant to be used with a torch.
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Re: Graphite crucible breaking down quickly

Postby rkundla » Thu Dec 14, 2017 3:06 am

eg123 wrote:"I bought a small one to try to make metal shot from my scrap silver and after the first time I fired it with a torch, it started to disintegrate."

Looks normal to me.
They are "not" meant to be used with a torch.


Well that explains it! I read somewhere you could do it, but it struck me odd how quickly it broke apart. :p
Chalamba
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Re: Graphite crucible breaking down quickly

Postby Chalamba » Thu Dec 14, 2017 6:36 am

Tourch - no, no!
It is not ment for that, take a cley cruicable for tourch melting or if tou need to melt bigger ammounts, or you need it for vacuum casting get an electric furnace.
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Re: Graphite crucible breaking down quickly

Postby ken3dcad » Thu Dec 14, 2017 10:29 pm

I'm surprised your torch stayed lit while heating inside that deep crucible.
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Messerbr
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Re: Graphite crucible breaking down quickly

Postby Messerbr » Fri Dec 15, 2017 3:15 pm

About how many casts should be expected when using graphite crucibles with a smelter? The one that is broken down the worst was used maybe 10 times

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