Excerpt from the November/December 2020 Casting Source by Jiten Shah.
The green sand casting process is the most widely used high-volume process because it is versatile and cost effective. In the case of an oil pan for a combine used in the agriculture industry produced by AFS Corporate Member Wabash Castings Inc. (Wabash, Indiana), the green sand process proved it versatility after eliminating some issues in the old design, which was cast in the semi-permanent mold process. Thanks to the flexibility in gating placement and design changes in the green sand process, the new casting reduced cost by using a common core for two cavities inside the part.
Critical wall thickness is maintained repeatedly with horizontally-parted green sand molding using a rugged common core for two mold cavities.
- Critical wall section thickness (1) in the oil pan is controlled with a massive common core that is well supported at the core print. The main body core has an overhang, like a cantilever, and if not designed carefully, it could sag or deform, resulting in uneven wall thickness. This could potentially lead to shrinkage porosities and non-uniform mechanical properties due to uneven cooling rates of thinner and thicker sections within the same casting.