Displacement on the surface mould and metal during the solidification of nodular graphite iron castings

The movement of the casting - mould interface during solidification of nodular graphite cast iron is influencing the occurence of internal volume defects. The final dimensions of a casting are a result of an interaction of the movement of the mould walls and the graphitizing ability of iron. The presented work is devoted to the experimental study of the movement of the casting - mould interface from the aspect of rigidity of moulding material and moulding box. The results of the measurements indicate that the time evolution of the interface movement can be divided into two stages. The course of the first stage is determined by the properties of the mould - the moulding sand strength and the moulding box rigidity. The development of the second stage, characterized by the casting expansion, depends on the graphitizing ability of cast iron, but also on the mould strength and the moulding box rigidity.