Analysis of tool wear, chip and machined surface morphology in multi-axis milling process of Ni-based superalloy using the torus milling cutter

This article presents an investigation into the life of the torus milling cutter with round cutting inserts when multi-axis milling process in high-speed cutting conditions of Inconel 718 under various of kinematic variants of multi-axis machining. The experiments were performed at varying tool axis orientation parameters of; lead angle: 1.37–20° and tilt angle: −18.86–20°. A new research approach was introduced to evaluate the possibility of extending the life of the torus milling cutter by changing the tool axis orientation in multi-axis machining. The analysis performed includes the tool life, tool wear patterns, and mechanisms as well as its relationship with the chip and machined surface morphology and kinematics variants of multi-axis cutting. The experimental results showed that tool wear has begun with smooth abrasion and chipping around the depth of cut line, which then progressed into flank wear and finally notching and flaking via mechanisms of abrasive and adhesive wears. However, for each of the analyzed kinematic variants of multi-axis cutting, the above processes proceeded in a completely different way. Thus, by changing the tool axis orientation in a controlled manner, it is possible to influence the cutting conditions in the tool-chip and chip-workpiece interfaces; hence, efficiently displace the point of contact and thus offset the negative impact of the concentration of tribological interactions at that point. Consequently, it was possible to slow down the tool wear development and prolong the torus milling cutter life to a maximum 78%. There was also a strong influence of multi-axis cutting conditions and tool wear patterns on the morphology of the chip and the machined surface. In conclusion, the kinematic variant of multi-axis cutting (i.e. axis orientation) using the torus milling cutter of Ni-based superalloys plays an important role in the possibility of extending tool life.