I just need to make a hole in the sand and fill it with iron. How hard could that be??Dazz- Yours is a big order and I admire you for the undertaking of it.
This is DIY. Getting a commercial foundry to do the job here would cost $$$$$$$$$$$$$$$Are you going to pour it yourself or have a Commercial or Art Foundry do it for you ?
The plan is to use cast iron engine blocks. These will already have the right metallurgy for my application.My first comment is you should probably look at Silicon iron and definitely use a Vanadium additive. This will improve fluidity and machining immensely ( Vanadium) . Years ago this additive which is put in just before the pour was called "Hot Shot" as it creates a exothermic reaction ( sparks) and raises the temp of the pour which adds to being able to pour thin walls.
I will need more than luck !!Good luck
After a bit of research, I found that SS can be set with an acid. Any acid would work but you would not want to use something like HCl that would release Chlorine into the metal.A few years ago, I found out that SS can be set using a catalyst, and so I actually purchased some catalyst, but have not tried it yet.
I have found references to using ships bottom coal as an additive to improve surface finish. This is very fine coal that get ground down as a result of the ship's motion. On contact with hot metal it will burn all the oxygen then just form a carbon layer. Fe2O3 (rust) has also been used but modern ceramic powders seem to be the modern approach.The thing to remember is that the bound sand only has to last long enough for the exterior of the metal to solidify.
Resin burns too, and it creates a charred interior of the mold, which I think actually helps with surface finish.
Since the binder is a small percentage of the sand, then the main point of contact between the molten iron and the mold is the face of the grains of sand, not the binder.
Google hot tears and rat tails.If a mold is made of some material that is too hard, supposedly it can cause a casting failure; not sure of the exact mechanics of that.