drago_arms

First Foundry, Advice on Castable Refractory

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Hello all, i've done a load of research into making a foundry, I've gone the way of the LPG tank lined with a heat resistant cement. However when i go to buy the cement i get blown away by the sheer variety of products i can buy. I wanted an expert opinion on two products:

 

http://www.morganthermalceramics.com/sites/default/files/datasheets/1_alumor_60.pdfo-

 

and

 

http://www.morganthermalceramics.com/sites/default/files/datasheets/1_alcast_super.pdf

 

The choice is between the Alcast_super which is a castable with max temp. of 1300c and the Alumor_60 which has a service temp of 1650c.

 

I am going to be splitting titanium in a molten salt electrolyte using the Metalysis FFC cambridge process, melting aluminium for casting, melting lead, melting various scrap copper/bronze.

 

What castable would you choose/recommend?

Do i need separate crucibles for different metals or can i re-use one safely?

 

extra info: coke/coal powered furnace, 5cm thick insulation probably, air forced.

 

 

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The first question everyone will ask, do you have any experience working with and handling molten metals?  The proper safety equipment for yourself and anyone helping?  The proper tools for handling the crucible of hot metal?  And the proper material to make molds out of? 

 

We get this question often here.  Molten metals are potentially more dangerous than hot solid metals, and any failure can have lethal or life altering consequences. 

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Hi there, no i have not had any experience with casting before however i am only casting under supervision of a metal fabricator who has had casting experience. They have got a good pouring dolly which keeps you far away from the molten metal and i would only be pouring on dry sand. The moulds will be cuttlefish and plaster of paris for aluminium, pewter and lead. The titanium never actually melts so it's not going to be poured. The hottest thing will actually be the salt at 801c. As for safety, leather gloves, aprons, long tongs, enclosed boots, full face mask and various anti-splatter bits to keep stray metal (god forbid) out of shoes and clothes. I will be using a commercially bought crucible (not one i construct myself). This is not going to be a high temperature foundry but i would like to build it so when i gain more experience i can move on to various other high-temperature bronze and other copper alloys. Hopefully this has quenched (no pun intended) your safety consciousness :) thank you for the response!

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Wow, that got complex in a hurry. Well, you've got one thing going, which is you have an experienced caster to help. And safety gear. And real crucibles. Can't answer all your questions about the commercial refractories, but if you're planning on playing with bronze, the lower temp one is a little too close to the pouring temperature. (2100 or so, vs. your 2350 or so max). A forced air over lump charcoal fire will easily exceed that in a furnace. 5 Cm is probably too thin if by insulation you mean refractory. If you're talking about lining it with something else though between the refractory and the shell, that's different. Be cautious about using something like Kaowool as an insulator, as exposed bits will cause fibers to melt/burn/break off and go into the air/your lungs. Not healthy breathing material. Don't mix crucibles. Also, you will need to talk to your mentor about preheating and checking them, as well as avoiding moisture...pretty much everywhere that you don't want minor steam explosions. Ram carefully with your castable, and heat slowly the first time (see above about minor explosions...). It sucks when an air bubble blows out the wall of your furnace. And remember that good ventilation is key since some metals (lead, brass, zinc) are toxic. And just for good measure, in building your furnace, remember all refractory eventually needs replacing, and plan for catastrophic crucible failure (if it comes apart, how will you get the metal out? A drain hole for starters....) Be CAREFUL, especially when trying anything new in casting, and have fun.

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And may I commend to your attention a forum dedicated to casting like backyardmetalcasting.com

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So, you are going to make titanium?
The process you mentioned is patented world wide.
If you make a dollar of profit you will be un court for the rest of your natural
life. They will pull out the stops to end your prodution.
Don't even begin this fool's errand.
The reason titanium is so expensive FYI
FYI is not because the ore is rare.
Titanium dioxide is the white in every gallon if paint made.
The expense is the cost of production
Understand even if you succeed in your highly dubious goal you can never sell any even in product form.

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What are you trying to make?  Where are you going to get your raw materials?  Buy them as ingots?  Or use questionable scrap?  What are you using for patterns.  Foundry/Casting is a very involved process, different for each type of metal and pattern.  And, as said above, potentially one of the most dangerous forms of metalworking. 

 

I suggest you read past posts on this site and others.  Spend time on line, and maybe even go to a library and read up on casting.

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BTW molten salt does not play nice.  Molten salt and electricity goes to double plus un-nice.  The folks who know the most will be the least likely to share that info due to liability concerns.

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BTW molten salt does not play nice.  Molten salt and electricity goes to double plus un-nice.  The folks who know the most will be the least likely to share that info due to liability concerns.

Yes, the comment about molten salt at 801C degrees was the giveaway.

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Wow ok, thank you all for your answers! 1) nobody special: thank you for the comprehensive response i will be sure to incorporate a drain hole and also be very careful with the castable, I had read about the side effects of Kao-wool and had decided not to use any because of the possible long term health detriments. 2)ThomasPowers thank you for the recommendation i shall check it out! 3)arftist I understand that the Metalysis FFC Cambridge process is a patented process which is why i wrote to them explaining my goals - what i didn't mention in my original post is that this is my final year project for school- completely no intention to sell/profit from using the process! I also understand fully the legal ramifications of selling said metal. Hopefully this 'un-dubifies' the idea :) . The reason i want to smelt titanium is because i have access to it (3rd most common metal element on earth or so i've been told), if i had access to alluvial gold nuggets i'd use a much simpler refining technique!

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Wow ok, thank you all for your answers! 1) nobody special: thank you for the comprehensive response i will be sure to incorporate a drain hole and also be very careful with the castable, I had read about the side effects of Kao-wool and had decided not to use any because of the possible long term health detriments. 2)ThomasPowers thank you for the recommendation i shall check it out! 3)arftist I understand that the Metalysis FFC Cambridge process is a patented process which is why i wrote to them explaining my goals - what i didn't mention in my original post is that this is my final year project for school- completely no intention to sell/profit from using the process! I also understand fully the legal ramifications of selling said metal. Hopefully this 'un-dubifies' the idea :) . The reason i want to smelt titanium is because i have access to it (3rd most common metal element on earth or so i've been told), if i had access to alluvial gold nuggets i'd use a much simpler refining technique!

How do you plan to maintain 801C using solid fuel? 

 

By the way, one could be a master "metal fabricator" and yet know just enough about casting to be extremely dangerous.

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801c is 1473.8f, i assumed that good quality dense compacted coke/coal would be able to keep up at least 801c for say 2 hours? Again i understand the fact that metal casting is possibly the most dangerous form of metalworking. njanvilman my castings will be very small, not working with large amounts of metal here all will probably be all less than 0.5 kgs (1.1 lb)i'm using scrap that i have been given and have bought. Not sure what you mean by patterns as i'm not going to be using green sand, however i will be using and investment lost-PLA (possibly toxic fumes i know)casting in completely dry fired gypsum plaster (for aluminium). and casting in old dry cuttlefish bones for pewter and lead. Any more questions or advice? Arftist what advice would you have to start/learn casting, or would you recommend that i just don't do it? :) thank you for your time :D

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http://www.backyardmetalcasting.com/

 

The Complete Book of Pottery Making by John Kenny

 

The Small Foundry Series by Stephen Chastain 

 

Any book on casting by Dave Gingery

 

Any book on casting you can find

 

Any book on pattern making (even a piece of lost foam is a pattern)

 

Any book on lost wax casting (more representative of how lost foam works)

 

Any book of metallurgy. 

 

It is a huge subject. 

 

There are many ways to hurt/kill yourself.

 

Metal is usually poured at 300F higher than it's melting point. Otherwise it will freeze before filling the mold.

 

Vapor from foam is pure poison as are most metal vapors.  

 

There are many ways a casting can go wrong. 

 

Did you know your pure plaster molds need to be kiln or oven dried for days before use? 

 

That plaster alone is very weak and is often mixed with sand and should be reinforced with metal mesh?

 

No, you will not get two hours burn from solid fuel. Sorry. 

 

I am not trying to dissuade you, simply help you realize the enormity of the task you have set before you. 

 

I would simplify it greatly by ignoring the vast fields of TIO2 in your backyard and worry about mastering zinc alloys by the end of your senior year (which is hopefully next year not this year.)

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arftist, i greatly appreciate your recommendations i am reading multiple books on the subject currently but will make sure to read the ones that you have described. I understand the risks and would not even start a pattern i was not 100% confident in. I am fully aware that plaster moulds are mixed with dried sand then fired until COMPLETELY dry, i was not aware of the metal mesh however i shall look more into it. As to the solid Fuel, i may have to consider gas. Perhaps i could explain the Process of splitting titanium and follow your advice on 'mastering' other 'lesser' (if i may use that term) alloys. I am fully aware of the enormity of the task which is why i chose it, (others in my year are getting pilot licences) Unfortunately it is the end of this year not the next :). Once again thank you all for all of your advice it is massively beneficial!

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Another problem with solid fuel is maintaining a consistent temperature, especially on a small scale. A muffle furnace might be large enough for your purpose, the temp can be controlled with micrometric precision. You probably don't have access to an induction forge but they're pretty darned nice ways to heat.

 

Frosty The Lucky.

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Frosty, I shall look into muffle furnaces, and unfortunately I don't have access to an induction forge however I have seen and read a LOT about them :) I was considering making one of these:

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Cool video, get it just right and you don't need no stingking crucible! There's a pretty long detailed thread about building induction forges here on IFI.

 

Frosty The Lucky.

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