Metal penetration is a defect that occurs when the metal enters voids between the sand grains of a mold. This paper describes the origins and countermeasures of two kinds of metal penetration defects.

In general, an increase in metallostatic pressure makes it easy to cause metal penetration. However, even if the metallostatic pressure is low, the cast iron penetration occurs. One of the cast iron penetration is caused by the volumetric expansion during eutectic solidification. When the castings has a closed loop of isochronal eutectic solidification, the internal pressure rapidly increases with the eutectic solidification proceeding in this region. If the sand mold is located in the region surrounded by the closed loop, the metal penetration occurs. The penetration defect of camshaft castings could be prevented by making sure of the directional solidification toward the riser with proper casting design.

Another metal penetration defect is greatly accelerated by the coating containing Te. The metal penetration originates in the remarkably lowered surface tension of the molten cast iron which is resulted from its reaction with a small amount of Te. The penetration defect of cylinder head castings could be prevented to control the surface tension with Cu addition.
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