# kiln for heat treating, annealing, melting aluminum??



## jumps4 (Sep 1, 2012)

has anyone ever used a kiln for any of these operations
I was also concidering using endospheric gas for case hardening in the kiln
steve


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## joe_m (Sep 1, 2012)

The current (aug/sep 2012) machinist's workshop magazine has an article on sandcasting an aluminum handle. The author uses a kiln, looks to me like a paragon. I don't remember too many details being given about it except that it does melt aluminum, but slowly.


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## bcall2043 (Sep 1, 2012)

I have thought about using the wife's kiln to heat treat but was told not to get it dirty. I would be afraid to use one to melt metal because if the crucible broke or molten metal was spilled in the kiln I would have heck to pay. Other than that the newer electric kilns have very good controllers that can be programed to ramp up, hold, and ramp down. If the kiln is yours and not the wife's I can't see why it wouldn't be okay to used to heat or melt metals instead of using it to just heat dirt.

Benny


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## jumps4 (Sep 1, 2012)

there was a 3 tier one on craigs list this morning for $75 it looked like brand new
i should have went and got it I'll bet its gone
steve


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## jumps4 (Sep 1, 2012)

this would melt a big chunk of aluminum
he didnt answer i left message
steve


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## DMS (Sep 1, 2012)

I see top loading kilns like that all the time on CL around here. I was recently in the market for a kiln, but was more interested in a front loader due to it's intended uses (enameling, silver clay, heat treating steel). I passed on the top loaders  but one would probably make a pretty decent furnace for melting aluminum/brass. The temp is right, and with a digital controller you can make sure you don't take it too high. 

Heat treating with a top loader seems problematic. If you are using air hardening steels, shouldn't be an issue, but for oil or water hardening steels, you need to get them out and into the quench pretty quick... could be tricky.

Oh, and be careful with shielding gasses in a kiln, I have read that they will drastically reduce the life of your heating elements when using units with exposed elements.


To bcall2043, get her some kiln wash if she hasn't applied any (its a sacrificial coating you put on the floor of the kiln to prevent glass/glaze from fusing to the floor of the kiln or kiln shelf). Then, get yourself your own kiln shelf. Small ones are about about $6. You just need something to set your parts on while they cook. You should be able to keep things really clean. I would also recommend getting some stainless steel bags for heat treat. They reduce decarburization, and should prevent that crud from flaking off in the kiln itself.


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## jumps4 (Sep 1, 2012)

thanks dms
i think i'll buy this if he calls back
cant go wrong for $75  but this is craigslist i have called on things and they would say it was supposed to be $750
craigslist is like walmart you never know what your going to run into ( people i mean )
i'm not ready heat level wise for brass yet i did a few pieces in my gas fired it's a whole new ballgame from aluminum
thank you again
steve


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## pdentrem (Sep 1, 2012)

At the shop we have found that when heat treating tool steels in our annealing furnace, with the belt turned off to keep the steel in the hot zone, that in using straight Nitrogen that we tend to get a dark, blackish scale on the steel. This is not an issue as most of the finish grinding or EDM work still has to be done. Now if we use cracked Ammonia, consist of Nitrogen and Hydrogen, we get a shiny surface with no scale. Now Hydrogen embrittlement could be a problem but we have not had that come up in our finished tooling.
Pierre


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## jumps4 (Sep 1, 2012)

I worked for a heat treating company when i was young and it was really interesting I built and repaired furnaces but i still learned a little from the plant guys, it is really interesting. we had a vacuum furnace that had a 15' enclosure that lifted up off the door to open, it was huge.
 it amazed me how the metalurgist a nice german guy could touch a piece of metal to a grinder and tell you what it was
steve


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## Rbeckett (Sep 2, 2012)

Did you seller ever return the call?  That would be a great tool investment for only 75 bucks.  You could always do pottery to help pay for it and to keep it busy.  The flea market would be a great dumping ground for finished projects to help make it self sustaining or even make a bit of profit to buy more material.    With an accurate timer and ramping you can d o all kinds of heat treating, glazing and melting.  Dont forget Argon or some neutral gas to prevent O2 contamination in aluminum castings.  Just a thought.
Bob


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## jumps4 (Sep 2, 2012)

no he didnt bob thanks i'm going to try him again right now
steve


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## machspace (Mar 3, 2013)

jumps4 said:


> I worked for a heat treating company when i was young and it was really interesting I built and repaired furnaces but i still learned a little from the plant guys, it is really interesting. we had a vacuum furnace that had a 15' enclosure that lifted up off the door to open, it was huge.
> it amazed me how the metalurgist a nice german guy could touch a piece of metal to a grinder and tell you what it was
> steve



I'm a metallurgical engineer (or at least I was in school, and a couple of years in industry).  The first time I opened an electric arc furnace at INCO (then the free world's largest Ni producer) they didn't tell me to hold my breath. The smell of SO2 is now etched into my brain.  Anyway, I was designing computer control systems for the smelting process, and tagged along with an older operator.   In smelting CuNi matte, the operator would slide an iron rod into the converter (melting chamber), pull it out, and tell me the composition from the colour of the streak formed on the iron rod as he pulled it out of the furnace.  He was eerily close to the sensors/subsequent analyses.  Very cool.


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