Die Casting

[holmsy]

by ceramic i assume you mean some kind of high temp ceramic not just one used for vases and pots and things.
brett

 

[Stacy E. Apelt - Bladesmith]

I've been casting for a living for 30 plus years now.The material is called casting investment,and is a plaster looking material made from christobalite (and other things). When mixed with water it dries to a plaster like state. Then when fired in a burnout oven (same one as used for knife HT) it burns out the wax model and bakes the plaster into a sort of porous ceramic state. The metal is injected by several possible methods(vacuum, centrifuge, pressure, )and allowed to solidify while the casting pressure is still applied. Once cooled down the "mold" is dunked in water or acid and broken apart and dissolved. The casting is recovered,cleaned up and polished. The casting will be an exact replica of the model, with only the shrinkage of cooling. Models are made about 10% larger than the finished product to allow for shrinkage and finishing losses.You can cast one wax or a hundred in one mold at a time.To make multiple copies of an item,the original prototype casting,made from a hand carved wax, is placed in a rubber mold that is vulcanized and after hardening ,cut in half to release the model. The mold can then be injected with wax or plastic and thousands of copies models made.
Stacy