Selection of cutting parameters based on tool strength

This study aimed to improve the efficiency of free cutting of metals by maximizing tool performance. This was achieved through the selection of cutting parameters based on the safety factor of tools. This work employed the finite element method with a Johnson–Cook constitutive model and an Arbitrary Lagrangian–Eulerian mesh adaptation algorithm to simulate the cutting process and reveal the stress distribution in the tool. The tool material was cemented carbide VK8, while the workpieces were steel 45, aluminum alloy 6061-T6, and titanium alloy Ti-6Al-4V. Model adequacy was confirmed by the agreement between the calculated tensile–compressive stress distributions in the tool and the isochromatic lines observed during cutting of lead with an epoxy resin tool. The study established the influence of cutting regimes, workpiece mechanical properties, and tool edge geometry on tool strength. An increase in the cutting depth from 0.2 to 1.4 mm led to a linear increase in the maximum principal stress σ1макс by a factor of 2.05, thereby reducing tool tooth strength. At a depth of 1.4 mm, σ1макс reached 780 MPa, ree-sulting in tool failure. The influence of cutting speed was shown to follow an exponential relationship. An increase in the rake angle reduced tool strength; for instance, during machining with a rake angle of 20° (σ1макс = 760 МПа), the tool failed to maintain its cutting capacity. The safety factor of the tool when machining aluminum alloy 6061-T6 was found to be 3.1 times greater than during free cutting of steel 45. The computational model and analysis of the relationship between tool strength and technological factors enabled the development of a methodology for assigning free‑cutting regimes that incorporate the safety factor of a tool.