|
(11) | EP 0 747 149 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||
| (54) | Investment casting method yielding cast articles with enhanced surface finish |
| (57) A modified investment casting process is provided which allows cast articles having
a smooth surface finish to be obtained while using casting patterns made of a photocurable
liquid polymer by a stereolithography process, or by molded thermoplastic materials.
Moreover, the process of the invention eliminates or minimizes the incidence of mold
cracking due to expansion of the casting pattern. The process involves first preparing
a casting pattern through a stereolithography process or through molding a thermoplastic
material. Thereafter, a wax or wax like coating is applied to the casting pattern
and an investment assembly is prepared. A mold is obtained from the investment assembly
by first subjecting the investment assembly to a first temperature range sufficient
to melt and extract the wax or wax like material, leaving behind the casting pattern.
Thereafter, the investment assembly is subjected to an elevated temperature in a second
temperature range that is sufficient to melt and extract the casting pattern. |