Bremen Castings, Inc. (BCI) is known worldwide for its quality gray and ductile iron machined castings. Casting process simulation at BCI is not only used to optimize casting processes but also to communicate root causes of a defect issue to a customer and to propose design changes to eliminate them.
Foundries commonly quote 200 or more castings per month. This is after they eliminate unfeasible parts. Of the quoted parts, usually 1-2% will eventually be awarded to the foundry. It is unfortunate, but practically unavoidable, that a foundry eventually ends up with some castings that several other foundries have failed to make. Nearly always when this happens, the casting design is at fault and leads to casting defects that cannot be eliminated by any casting process adjustments or only at unreasonably high costs. Casting buyers usually do not volunteer information about this history when they send requests for quotes to yet another foundry. Many foundries quickly “give up” in such cases and cancel the contract, even if this will incur penalties.
Bremen Castings has taken a different approach: in the case described here, it ran the part through MAGMASOFT®, evaluating if cracks showing up in 8% of the castings were caused by the casting process and could be eliminated by changing it. A complete filling, solidification, and stress simulation during the solidification and cooling process revealed that the casting process itself was not at fault. The design of the casting lead to very high stresses not only in sharp corners, but also on surfaces that were bent by distortion during the solidification and cooling process. The simulation results clearly showed how the casting distorts, eventually leading to stresses and strains that exceed the strength of the material at the temperature level at that time.