The nodular cast iron parts of the split gear box are obtained by machining the upper and lower gear boxes in pairs. The overall dimension of the nodular cast iron parts of the upper gear box is 788 mm × 340 mm × 287 mm, the overall dimension of lower gear box ductile iron is 992 mm × 465 mm × 287 mm, main wall thickness 12 mm, shaft hole wall thickness 50 mm, casting mass 121 kg, upper and lower gearbox joint flange wall thickness 48 mm, ductile iron structure as shown in the figure. The material number EN-GJS-400-15 requires that the quality of nodular cast iron meet the NDT indicators shown in the table.

Nodular cast iron for railway gear boxes are typical thin-walled nodular cast iron with high quality requirements and large demand in casting production. Due to the thin wall thickness and structural limitations of nodular cast iron, it is difficult to feed and easy to shrink and loosen; The spheroidizing element Mg in nodular cast iron liquid iron is easy to oxidize, the improper inoculation treatment is easy to produce MgO slag, and the inoculant is uneven and non-molten, resulting in slag inclusion defects. It is difficult to pass the first batch of certification and enter the qualification of qualified nodular cast iron supplier.

For the thin-walled small nodular cast iron of railway gear boxes, the use of flat cast side dark hot risers can supplement the key areas of the box with molten iron to realize the sequential solidification of molten iron. The MAGMA software is used to assist in the analysis of molten iron flow rate, thermal modulus and shrinkage porosity criteria, so as to realize the accurate feeding of various parts of nodular cast iron, so as to prevent the occurrence of casting defects such as shrinkage porosity and shrinkage porosity.