Abstract This paper describes an experimental investigation on machining of a difficult-to-cut material, AISI D2 steel of hardness 62 HRC with PCBN tools. It was found that the most feasible feeds and speeds fall in the ranges 0.08–0.20 mm/rev and 70–120 m/min, respectively and that most of the tested PCBN tools reached the end of life mainly due to flank wear. The highest acceptable values of tool life and volume of material removal were obtained at the lowest speed tested (70 m/min), indicating that this speed is more suitable for machining the selected tool/work material combination. While the highest feed used resulted in the highest volume of material removal, lower feeds resulted in higher tool life values. It was also found that the most appropriate feeds for this type of hardened steel are 0.14 mm/rev for finishing operations and 0.20 mm/rev for roughing operations. It is shown that for the considered conditions, the relationship between tool life and cutting conditions can be represented by a Taylor type tool life equation, while that between forces and cutting conditions can be represented by power function type equations.