Shell Mold Casting

Benefits of Shell Mold Casting:
1. Shell molding process offers better surface finish.
2 Shell molding process offers better dimensional tolerances
3 Shell Molding Process offers higher throughput due to reduced cycle times.
A heated metal pattern is covered with a mixture of sand and thermoset plastic. This causes a skin of sand 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.

The materials that can be used with this process are cast irons, and aluminum and copper alloys. Typical parts made with this process are connecting rods, gear housings, lever arms etc.
· The basic process for these molds is,
1. Create two mating patterns of desired shape.
2. Coat the molds with a shell (sand and binders, such as a resin) until desired thickness and other properties are obtained.
3. Cure the molds and remove the patterns.
4. The mold halves are mated and held firm while metal is poured.
5. The final part(s) is removed.

This technique can be very economical.
· Special care must be taken to assure venting for gasses, as the mold media is less porous. · This method can easily use cores and chills to make complex molds.
· Graphite molds can be used for materials that would normally react with other materials used for the molds

Shell molding process offers better surface finish, better dimensional tolerances, and higher throughput due to reduced cycle times.

A fairly high capital investment is required, but high production rates can be achieved. The process overall is quite cost effective due to reduced machining and cleanup costs.

The materials that can be used with this process are cast irons, and aluminum and copper alloys. Typical parts made with this process are connecting rods, gear housings, lever arms etc.
Shell Mold Casting