Just wondered if anyone can give me an idea on how steel will cast in
a vacum caster ? Is this done very much with jewelry ? Is the melting
temperature a factor ?
Thanks
Brett Garrett
www.brettgarrettstudios.com
Vacuum casting can mean a variety of techniques depending on which
industry you are in. If you are talking about lost wax investment
casting with vacuum assisted pouring you will need a high
temperature investment and most investments used in vacuum casting
jewelry will not stand up the the high temperatures needed for steel
they are all rated for metals with a melting point below 2000F. If
you have access to a centrifuge then use platinum investment but the
platinum investments are too dense for use in vacuum assisted
casting. Most small steel lost wax casting is done by melting with a
crucible furnace and using ceramic shell molds that are gravity
poured.
Your bigger problem may be melting the steel without ruining it. If
you don’t have a induction furnace with a controlled atmosphere or a
gas fired crucible furnace with a properly adjusted flame it will be
very easy to over oxidize the steel when trying to melt it with a
torch.
James Binnion
James Binnion Metal Arts
Hi James,
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.