Many castings are doomed to failure before they ever leave the drawing board. This is because the designer failed to take the foundry aspects of the casting process into account during the design of the casting.  Once a design is fixed, it is difficult and costly to make alterations or concessions.

Modern casting processes and techniques have reached a highly advanced state. As a result, it is now possible to routinely achieve high quality castings, that are based on sound design principles, and produced in a modern well equipped and well managed foundry.

Walls Fillets and Ribs:

NOTE: The following is not to be considered an Engineering Standard but rather a guide to good casting design.

A production problem of fundamental importance to foundries is establishing a sequence of progressive solidification that will compensate for the change in unit volume as the cast shape solidifies. The designer should, wherever possible, use sections that are tapered to increase in thickness toward points accessible to feed metal. If it is necessary to join light and heavy sections, a gradual increase in thickness is most desirable. If tapered sections are not practical or the increased expense of building the pattern or mold is not warranted, a uniform section should be maintained. Intersecting surfaces forming junctions of metal thickness should be joined with fillets in order to obtain improved foundry characteristics and a more uniform distribution of stress in service.

The primary concern in designing these sections is a fillet radius that neither concentrates stresses nor promotes the development of hot spots due to heavy concentrations of metal.

Sand Casting Tolerances
The sand casting process is relatively inexpensive, acceptably precise and above all, highly versatile. It can be utilized for castings ranging in size from a few ounces to many tons.

Dimensional control and consistency in sand castings ranges from about +/-0.030 to +/-0.125 inches. Within this range,the more generous tolerances apply