Shell Molding
process offers better surface finish, better dimensional tolerances,
and higher throughput due to reduced cycle times.
A heated (200 ?C / 392 ?F) metal pattern is covered with a mixture of sand and thermoset plastic. This causes a skin of about 3.5 mm (0.125 in) of sand/plastic mixture to adhere to the pattern. This skin is removed from the pattern to form the "shell mold". The two halves of the shell mold are secured together and the metal is poured in the shell to form the part. Once the metal solidifies, the shell is broken.