Effect of graphite nodules on the EDM machinability of ferritic SG cast irons

This investigation examines how graphite nodule counts and average nodule diameter affects the material removal rate (MRR) of Electrical Discharge Machining (EDM). Experimental results indicate that the MRR increased with a decreasing average graphite diameter and increasing graphite nodule count. This phenomenon was attributed to a rigged EDMed surface with a higher ridged density produced. However, the ridged density increased continuously with the number of graphite nodules, thus increasing the material removal rate. Furthermore, there is an essential relationship between MRR and pulse on time for all specimens with a pulse on time for the maximum MRR of 100 μs. The agreement correlation in the quantitative data of ridged density suggests that while the EDM surface feature is similar depends on both pulse on time and graphite nodule counts.