Research on key casting process of high-grade CNC machine tool bed nodular cast iron

The bed structure of high-grade large-scale CNC machine tools is crucial for maintaining their long-term service accuracy. This study focused on the key casting process of large nodular cast iron beds. AnyCasting software was employed to simulate and analyze the casting scheme, and then the mold filling and solidification processes were proposed based on the simulation results. The proposed casting scheme indicates that the designed gating system exhibited excellent filling capability. The dual sprue ceramic pipe bottom pouring technique, in conjunction with the chills, not only improved casting efficiency but also met the requirements of sequential solidification design. The castings possessed a dense microstructure characterized by uniform and stable phase composition, primarily comprising lamellar pearlite, with ≤0.5% of phosphorus eutectic and cementite. Furthermore, the microstructure of these materials displayed favorable graphite morphology with a spheroidization rate exceeding 85% and spheroidization grade of 2–3. This study has important academic and application value for the casting process of producing low-stress, high-grade CNC machine tool bed cast iron materials.