Foundry Refractory Qualities 2

[edstimator]

So after researching I have come to the opinion that Pearlite and portland cement make an excellent refractory with the major drawback being its inability to withstand heat much over 900 deg. F. If I am wrong about the temp please tell me. That's why I'm posting.
A major plus however is that pearlite and portland is no doubt the cheapest refratory mix available.
So what I plan to do is to buy a small amount of castable refractory to use as a liner and then use the cheaper mix to back that up.
Is that going to work?
The whole furnace is contained within a steel case so cracking should not be an issue?
I live in LA is there furnace cement around here?

 

[edstimator]

I'm surprised no opinions on this subject. seems like there is room for a bunch of difference of opinion on this one but I guess I just have to try it to see if it works. In the end, as long as I don't blow myself up and it works then it's all good.

 

[arunmrao]

edestimator,

Please be careful in your project. In my opinion,seeking assistance of a local technical centre or college will be helpful. Without any disrespect to any of the contributing members in your thread,not all information that you seek are complete. They are mere guidance and you need to weighing the pros and cons,before attempting to proceed further.

Finally,please be patient,if no one has responded . Meanwhile continue using the forums and start contributing too!

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[edstimator]

Will take your advice to heart and go slowly untill I'm sure of what I am about to do. Thanks for taking the time to involve yourself. I appreciate it.
I always TRY to contribute in the arenas that I am an expert in.

 

[Compositepro]

Sealed wood is a very common mold making material, and should work for you. If you cast aluminum molds you still have to make a mold for the aluminum.

 

[edstimator]

Hey composite pro, you are absolutely corect. Hardwood stands up to the rigors of drycast quite well. Combine that with the fact that I know a shopbot owner that could make that mould for me and it starts looking pretty attractive. I am really looking for an excuse to have to build a foundry I know but I really could use one. Ceartainly don't have the time or money to invest though because I'm building a room.
I think I will basically do both since it's taking much longer to make the furnace than anticipated.

 

[Compositepro]

Melting aluminum is extremely easy, I did it in grade school. Charcoal or natural gas will work. A compressor is not a a good air source.You do not need 100 psi or even 0.1 psi. You need a blower. The hardest part is finding a suitable crucible material. Molten aluminum will dissolve steel.

 

[edstimator]

hey composite pro, I believe you are correct in all counts. I plan on buying a commercial crucible and the reason why is that the idea of having 10 pounds of molten aluminum splashing my groin is not going to happen. I don't want to be pulling the crucible out and have it break or something unexpected.
On a high note I just got off the phone with a local supplier of refractory so I believe I am good on that front. I'm going to have to bring my welder down from the cabin to manufacture some tongs and such.
Should be fun. I am a LOUSY welder with a good buzz box.
It may take a little longer to fire it up than I was hoping for but I am moving in the right direction.

 

[edstimator]

BTW Compo, I'm using a hvlp compressor for the air supply. High volume, low pressure and capable of running all day with back pressure or no back pressure without any problems. I think that is an upgrade from anything I have seen online.

 

[slvr]

Hi, what type of furnace are you intending to build? What materials do you wish to melt? What quantity? What do you want to cast?
sorry, lot of counter questions, but I need the answers to give you a tailored answer to your question.

For an example which worked quite well for me to cast small amounts of brass, you can watch this video of my at home casting project:

http://www.youtube.com/watch?v=EBN7SgjeHXI

(a lot of trial and error, but it is the end result that counts!)

We have used a commercially available crucible, and put it in a ciruclated heat furnace (a little gas and forced air), lined with (compacted) glass wool (insulation material). after some initial trial and error, we got things right, and could melt 1 to 2 kg of brass in about half an hour (at temperatures of 1200-1250 degrees Celsius). Different setups of this principle are of course possible. The best results are made when the distance between crucible and furnace lining is relatively small (few cm at most), this way the crucible heats fastest.

Good luck with your furnace project,
BR,
Sylvia

 

[edstimator]

hay ole slvr, whell, I'm trying to build a charcoal briquette furnace to melt aluminum. Saw the furnace you built on you tube. Nice job on both the furnace and on the production. Very professional. The furnace I am building is run on charcoal and forced air of course and it works real well. The advantage of the charcoal is the cost to operate is much less with charcoal than with propane. I have found a local refractory guy and I will no doubt buy some castable refractory from him but I have an apointment with a local aluminum foundry who has offered to teach me how to build an adequate mold and they will cast the parts that I need. This is very attractive on large pieces. I have plans to cast machine parts for the majority of projects at the moment but since I have yet to do it I am keeping an open mind. Brass seems further away down the learning curve so just sticking with al. right now.
I tried it out as it sits and it melted a cup or so of al. like right now. and that was with short bursts as I was trying not to melt or blow up my homemade refractory first time out.
I need a crucible and tongs gloves money to pay for all that crap and a beer and I'm good.