Comparative study of 3- and 5-axis CNC centers for free-form machining of difficult-to-cut material

This paper examines the cost effectiveness of 3- versus 5-axis machines for the machining of a turbine blade made of alloy steel EN 34CrNiMo6. The acceptable surface finish cannot be achieved when a free surface is machined on a 3-axis CNC center due to the variation of the tool׳s position in relation to the part׳s surface. A feed-rate adjustment algorithm is proposed in this paper as a way to compensate for that limitation. To that end, the following two research questions are addressed: (1) if the algorithm is used, can the required surface finish be achieved on a 3-axis CNC center, and (2) which of two alternatives: a 3-axis (assuming the algorithm is executed) or 5-axis CNC center (without the algorithm) will be more cost effective?