The performance of ceramic and cermet cutting tools for the machining of austempered ductile iron

Abstract

In this study, the machinability of austempered ductile iron (ADI) having a ferritic structure was examined. For this purpose, three types of ductile iron materials (as cast, ADI-250, ADI-375) and two different types of cutting tool materials (ceramics and cermet) were used. To emphasize the role of austempering process, ductile iron (DI) specimens are first austenitized in salt bath at 900°C for 120 minutes after which they are quenched in salt bath at 250°C (ADI-250) and 375°C (ADI-375) for 120 min. Machining tests were carried out at various cutting speeds (100–500 m/min) under the constant depth of cut and feed rate. The performance of both ceramic and cermet tools were evaluated based on the workpiece surface roughness and flank wear. Wear conditions of the cutting tools were characterized by scanning electron microscope. The results point out that the lower austempering temperature results in increasing of the cutting forces, while better surface roughness is obtained. Additionally, the results indicate that the tool wear occurs mainly on the flank face. However, higher cutting speed results in chipping formation in cermet cutting tool.