Performance evaluation of self-propelled rotary tools and fixed round inserts in machining

This study evaluates the analysis of round inserts (Fixed and Self-Propelled Rotary Tools) when machining hardened steel. Self-propelled rotary Tools (SPRTs) exploit the entire perimeter of the insert rather than a specific cutting edge, minimizing insert wear and maximizing insert life. It is considered an environmentally friendly process. Tool and insert geometry have a direct effect on the surface roughness. Previous studies highlighted the significant effects of one inclination angle on surface roughness. Despite previous research that investigated only one inclination angle, in this research, the effect of both inclination angles has been investigated, and a new method for simultaneous application has been used. The optimal use of both inclination angles has significantly improved the quality of the machined surface. Therefore, an optimal holder has been designed and fabricated based on the cutting forces and component shapes, allowing inclination angle changes. The full factorial design of the experiment is adopted, and the effects of the horizontal and vertical inclination angles and feed rate in fixed tool and SPRT turning have been evaluated, each in 3 levels with a total of 54 experiments. The equivalent insert radius is defined using the inclination angles and an analytical model is developed concerning the equivalent insert radius to predict surface roughness. The proposed model accurately estimated roughness in fixed tool turning for an R-square of 0.81 and 0.76 for SPRT turning. In the best condition, the surface roughness has been measured at 0.472 μm in the fixed tool turning and 0.409 μm in SPRT turning.