The commercial foundry I looked at for a potential job placement,
was a steel foundry, they used a large induction steel melter, they
poured into resin bonded sand, and it was gravity pour. Turned out to
be too limited, and I would have gone nuts with boredom.
When you’re dealing with rather small volumes of metal in jewellery
manufacture, some of the casting techniques used are often
impractical for larger operations. Gravity is usually chosen due to
simplicity and cost.
Maybe some of the steel casting sands may be an option. Definitely
not as fine a finish as an investment plaster, but some of the sand
formulation are very fine indeed, only needing minimal clean up.
The two options open to a person using sand are traditional cope and
drag, and lost foam. Lost foam required a very dense foam if you
want jewellery quality results, and any metal heavier than aluminium
needs bonded sand, as opposed to loose sand. The advantage is that
you don’t have any burnout cycle to worry about, but you do have to
worry about the gasses that come of the vaporising polystyrene.
Regards Charles A.