The discussion on vacuum vs. centrifugal has been very
informative but within this disucssion there seems to be a common
thread regarding proper casting temperatures. My question is: Is
there available anywhere some reference material as to what the
proper temperatures are for the various metals [particularly
sterling], flask sizes, object sizes and types, as well as, their
relationship to the different casting systems [eg. does vacuum
require a hotter or cooler temp. for the same flask as
centrifugal?].
Thanks
Lorne
Dear Lorne:
Most major equipment manufacturing companies and suppliers of
materilas will have this info. Kerr is one of the standards of
the inventment companies. It depends upon both the material you
are casting and the type of item to be cast. Gold-reguardless of
karat content should be cast at about 800 for thick pieces (heavy
men’s rings) and about 1000 for filigree and other fine, lacy
pieces. Sterling at about 1000 to 1200 degrees.
Hope this helps;
Steve
hello Lorne, As far as temp goes for flasks and metal, it is not
easy to explain without seing the item you are casting and
knowing what particular equipment you are using.I have used
probably 60 different casting systems/machines from allsorts of
manufacurers.From a simple neycraft centrifuge to a $65,000
pressurized vac casting system. A pressurized casting system will
cast at a lower flask and metal temperature than any other
machine known to man… and with a good technician operating the
system will give you the best castings you have ever seen. Most
of my castings in sterling ( done on a simple vac system ) are
done at between 900oF to 1050 oF … for very heavy items we have
gone as low as 700oF. Metal temp by eye… this means the metal
is melted and you pour at the moment when you get a nice mirror
finnish on the melted metal. For my metal , this 1850 oF…±
25of I use united precious metals #88 silicone based sterling
alloy. What metal you use also plays an important part in your
castings.So does the location and size of your sprues. If your
items are not filling at 1050of because they are filligree ,or
thin, then increase your flask temperatures until they do fill. We
have cast very fine filigree (80 pieces on a tree) at 1250of and
gotten perfect fills and 0 porosity. If you could email or put up
on a website a picture of an item that you would like to cast and
a description of your machinery, i may be able to give you a
hand. Sincerely, Daniel Grandi http://www.racecarjewelry.com