Simulation showed that a hotspot is located in a critical area which might be exposed after machining. A number of corrective actions were investigated to eliminate the problems, such as reducing the volume of the area to attain a faster cooling rate, applying a modified tempering system, and adding more overflows to achieve a favorable temperature profile and move the hot spot to an uncritical area which is not machined. In reality, adding more overflows was the most efficient of the three alternatives, as well being the easiest way to modify the existing tooling. After the foundry added the overflows, the scrap rate was reduced to 3 %.
* Courtesy of Dognam Precision, Korea