Assessment of Machinability of ADI Using Surface Roughness and Resultant Chip Formation as Criteria

The machinability of various grades of austempered ductile iron (ADI) has been investigated by using the surface roughness and the resultant chip formation as criteria. Grade 1 ADI, Grade 2 ADI, and Grade 3 ADI were commercially produced, commercially heat treated and machined under controlled conditions using coated carbide inserts with coolant in the laboratory. The milling performance of the various grades was compared to that of AISI 4340, which has a similar hardness to Grade 2 ADI. Grade 100-70-03 ductile iron was used as a reference material in the drilling study. The results of this study show that the surface finish of ADI and the resultant chip formation give quick indications if proper cutting parameters were used during machining of ADI.