| Each of the two molding methods has relative
capabilities, advantages, and costs, as shown in the table below. |
|
Target |
Green Sand
|
Shell-Mold
|
As-cast dimensional
tolerance across 1" |
+/-
0.030 |
+/- 0.030 |
+/- 0.008 |
| Nominal surface finish
(RMS) |
500 |
500-900 |
300-500 |
| Minimum Section
Thickness |
0.19
inch |
0.25 inch
|
0.15 inch |
| Heat
Transfer Efficiency |
High |
Low
(Sand) |
High
(Metal Fill) |
| Intricacy of detail |
Fair |
Fair |
Very Good |
| Tool/Pattern Cost |
Medium |
Low
(Wood) |
Medium
(Metal) |
|
Note - The performance
numbers for green sand and shell mold are typical. Actual values for a
given foundry could be higher or lower depending on the equipment and
expertise at the foundry. |
|
Given the
requirements for surface finish, section thickness, and the heat
transfer efficiency for the support rotor, choose an appropriate molding method --
GREEN
SAND , SHELL MOLD |
|
