Evaluation of the Performance of CBN Tools When Turning Austempered Ductile Iron Material

The study deals with the machinability properties of austempered ductile iron using cubic boron nitride cutting tools. To emphasize the role of the austempering process, ductile iron specimens were first austenitized in salt bath at $900°C$ for $60min$⁠, after which they were quenched in a salt bath at $250°C$ and $325°C$ for $60min$⁠. Machining tests were carried out at various cutting speeds under the constant depth of cut and the feed rate. Tool performance was evaluated based on the workpiece surface roughness and flank wear. The influence of the austempering temperature and cutting speed on the chip form was also studied. The results point out that the lower austempering temperature results in the increase in the cutting forces, while better surface roughness is attained.