lost wax casting

Casting – Lost Wax Process
The lost wax casting process is widely used as it offers asymmetrical casting with
very fine details to be manufactured relatively inexpensively. The process involves
producing a metal casting using a refractory mould made from a wax replica pattern.
The steps involved in the process or the lost wax casting are:
· Create a wax pattern of the missing tooth / rim
· Sprue the wax pattern
· Invest the wax pattern
· Eliminate the wax pattern by burning it (inside the furnace or in hot water). This
will create a mould.
· Force molten metal into the mould - casting.
· Clean the cast.
· Remove sprue from the cast
· Finish and polish the casting on the die.
A general description of the process is as given above, however it might need to be
modified to account for different alloys being used. Cobalt alloys have melting
temperatures between 1250 and 1450oC which is higher than the investment made of
gypsum decomposition temperature. Because of that, the gypsum investment must be
replaced by phosphate or silica bonded type material.
The method of the alloy melting also depends on the alloy used since the temperatures
required are higher than the ones which can be achieved using a torch, or the alloy can
chemically react with gases.