Rudimentary tilting furnace.

[Amol Gupta]

So I came across a sreertips video of melting silver.



I like the idea of wrapping the ceramic wool around the crucible, makes for a very good candidate for tilting furnace.

A few things I'd like to do differently, firstly I'd like to use an electrical source for heating(kanthal wire most probably) instead of a torch flame, wrapped around with ceramic wool this way the heat source will be consistent during the melt even at the time of pouring, leaving no residue on the crucible which is often the case if the charge is not hot enough.

A set up like this will be easy to mount and pour from, making it a one man job.

Something I cannot figure out is the material for the crucible. I am looking for something that is thermally conductive but electrically insulated. My first choice was using a graphite crucible it has very good thermal properties but it is also electrically conductive which makes it dangerous for handling.
I was thinking of coating the crucible with some material as is shown in this video.



But I guess I'm better of using a suitable material, I have seen furnaces where the heating element is coated with some sort of ceramic being extensively used but I'm not sure of the material.

Any input on the same would be highly appreciated.

Thanks.

 

[4metals]

The issue with a tilting furnace is the crucible tends to want to fall out of the furnace so it has to be secured in place. There are 2 ways I have seen this done. One method uses what are called T crucibles. They have a pour spout built into the crucible. The entire crucible sits in the furnace and a lid secures it in place. These furnaces are heated by heat coils and the entire furnace tilts to pour. One manufacturer of these furnaces is Vcella kilns HERE. The smallest one has a number 16T crucible and they go all the way up to a #400 crucible. Heat up is longer and the max temp is 2300ºF but the crucibles change out quickly. Plus they are a fraction of the cost of an induction furnace of comparable size.

Another route used with induction furnaces is to actually cast the crucible into the furnace and using a moldable refractory make a pour spout to allow the molten metal to pour when titled. There are 2 types of refractory used to set the crucibles one to set the crucible into the furnace which I believe is called grog, and the second to mold the pour spout which which is called shamrock. The down side to this is the maintenance required to cast the crucible in and the set up time as well as the time to change out a crucible.

The video of the gentleman coating his graphite crucibles is interesting. He uses pure graphite crucibles which break down when exposed to oxygen. The coating effectively keeps the oxygen from reacting with the graphite.