Metal Casting Zone

Hello;

In my limited casting experience I have used the burnout oven of a local studio for wax burnout. I no langer have access. The projects I'm currently working on are all flat work. It would be easy enough for me two use two part investment molds in the same way you do with cuttlefish bones. Looking at the burnout cycles for the investment I see lots of comments like "to fully vaporize the wax" and " in order to remove all wax residue". So, I'm wondering if the the long, high temp burns are really to set the investment or just to remove the wax. Perhaps a 5-6 hour heat soak at 500ºf would be enough to super dry the investment and pre-heat it if the wax was not trapped? Point being that I could make an oven out of refractory brick and old oven elements that could go even 800ºf but not the 1350ºf the investment instructions call for. I'll be casting silver, BTW.

You have to burn out the wax that soaks up in the investment mold.
I have been trying to get around the long burn out myself.

I tryed to use "foam in a can" to make patterns but it don't want it burn out like Lost Foam does. I still have some hope for it.

Also tryed Lost thin shell hot glue, it works fair if you can get it thin.
And I have mixed used blasting sand with RTV rubber and cast Al in it. That shows hope too.

Point being that I could make an oven out of refractory brick and old oven elements that could go even 800ºf but not the 1350ºf the investment instructions call for.
What 800F is just what the oven gos to. The elements themselfs will go much higher.
All the ones I have seen glow orange which is 1800 or so.
You just need a control that will let them heat more or just cut them on/off like a stove top control does(it has a timer heater in the control). This Power Controller is the same as a stove top element uses.
www.budgetcastingsupply.com/Heating_Elements_Controllers.php

I have seen burn out units made with the stove oven elements (useing a high $ digital control) and that was by a guy who did it for a liveing.
This is a pic from his web site, check out the index.
It looks like a ready made kiln and it is, but the elements you see are from a oven just like in a house. He rebuild it and that is what he used.
www.unionsteam.co.uk/gallery/casting/index.cgi?IMGP0469.jpg

from my experience you will need to get over 800 degrees.

the wax will melt out lower but the investment must be completely clean.

the wax residue will stay with the investment and cause problems while pouring.

1000 degrees is close, but the 1350 sounds better.

organic will be burned out at 1000 but not all the wax.

foam also burns out at lower temps.

i hope this helps,

irontwig

Thanks for the replies. It does clarify that The heat is not curing the investment but burning out the wax. Over the long dark winter I may dumpster dive after some oven parts. The insulating fire brick is the only thing I'd have to buy. I did a net search and that was dismal. Where in the US can one find them?

Here are some pixs of "lost hot glue"
I found that if I heated the thin glue shell and let it run out the rest will burn out when poured. I only had to heat it to 300-350F and it was cool at pouring.

This was a 2 piece glue pattern I made in a RTV mold and glued together.
The next trys will be with filling the mold and melting the glue out.
That will save glueing the pieces together and won't leave the bad parting line the glued ones have. (Hopefully)







It looks very much like a die casting but for my know screw-ups.

I dont think I could die cast a shape that intricate. Great job!

Thanks

I want to get the finish as good as what it is around the neck part.
I'm also finding out how to redo the pattern so any after casting finishing will be easyer. Hope to sell them as gear shift knobs.