The interaction between the high-temperature molten metal and porous mould leads to various types of defects in castings. In a severe case, metal or metal oxides may fill the voids between sand grains. The penetration of molten metal appears as a surplus of metal adhesion, containing sand from the moulding material. The removal of this adhesion and the correction of the shortcomings of surface quality require additional machining, cleaning, or repair. This also draws major yield losses, environmental load and extra noise pollution. Studying the origins of penetration defects is important for foundries to avoid the formation of this type of defects. There are tools developed for this purpose those can be utilized in both laboratory and industrial conditions. A special type of penetration particular for cast iron, the metal expansion penetration will be discussed.

In this webinar, we will discuss how one can suppress the penetration of molten metal into the porous medium, especially penetration of molten cast iron into the sand mould, based on a simple theory. The valuable X-ray image movie of the penetration will also be shown, and you will see how the penetration takes place. The most prevalent test method to study penetration defects will be introduced through a particular case study.