On the one hand, the temperature of the nodular cast iron is reduced on the one hand, and on the other hand, magnesium and rare earth elements form slag in the ladle and pouring system. Therefore, the fluidity of the molten iron/Ductile Iron Castings Manufacturers decreased after spheroidizing treatment. At the same time, if the slag into the cavity, will cause inclusions, pinholes, casting surface roughness and other casting defects.