Analysis of machinability in ductile iron casting

In ductile iron castings factors affecting to solidification are melt composition, Mg-treatment, inoculation and cooling rate which affect graphite structure formation and finally on properties of end casting product. So, care should be taken to achieve better quality product. This work deals with the analysis of variation in machinability of ductile iron casting component, which is usually noticed in industrial production foundries. There is a big challenge to eliminate or minimize these variations. The effect of different process parameters such as carbon equivalent, inoculation and inoculants used, that lead to the variation in microstructure and micro hardness is analyzed. The influence of above process parameters is investigated by mechanical testing (especially micro hardness) and microstructure analysis of the cast component of the regular component produced in the foundry. The basic objective of this work is to analyze the variation in machinability for shock absorber component. The microstructure analysis of the shock absorber component at defective location is carried out. It is observed that average nodularity obtained is 37%, which shows that graphite structure is not nodular. Average micro-hardness measured at defective location is around 346 HV, which is almost double than the required hardness for the component. Thus nodularity and micro-hardness are the two major factors which affect the machinability of the component which require frequent tool change while performing milling operation.