Coolant strategy influence on tool life and surface roughness when machining ADI

Austempered ductile iron alloys (ADI) are an interesting class of materials because of their unique microstructure and mechanical properties. When subjected to austempering treatment, ductile iron transforms to a microstructure consisting of ferrite and stabilized austenite rather than ferrite and carbide as in austempered steels. Because of the presence of stabilized austenite, austempered ductile iron (ADI) exhibits an excellent combination of strength and ductility together with good fatigue and wear properties. Accordingly, there is a growing interest in using ADI in several applications due to its mechanical properties. However, as with difficult-to-cut materials, the machinability rating of ADI is low and there is still a need to understand the impact of the cutting process parameters. Machinability of a material depends not only on its properties and microstructure, but also on the proper selection and control of process variables. The current work is focused on performing a machinability analysis of ADI in order to understand the effect of the cutting process parameters on the machined surface quality and tool life. It also studies the effect of different coolant strategies. Thus, the motivation of this study is to develop a better understanding of the influence of cutting parameters and cooling strategy to be able to machine ADI directly with acceptable tool life and cycle time. The design of experiments technique and response surface methodology is employed to analyze and model the measured responses. In addition, the cutting tool wear mechanisms are identified and discussed.