Evaluation of a Self-Propelled Rotary Tool in the Machining of Aerospace Materials

Abstract

The self-propelled rotary tool (SPRT) incorporating round-shaped cemented carbide cutting inserts exhibits superior wear resistance when machining titanium IMI 318 alloy under finishing conditions involving a low depth of cut of 0.25 mm. The rotary cutting action extends tool life by more than 60 times compared with the rhomboid and round inserts used in single-point turning. Excessive chipping was the dominant failure mode when machining IMI 318 with the SPRT due to thermal and mechanical shocks as well as vibration during machining. When machining nickel-based Inconel 718 alloy with the SPRT tipped with CVD-coated carbide inserts, improvement in tool life was not significant as a result of severe attrition and abrasion wear mechanisms. Component forces recorded with the SPRT were lower than those obtained during conventional single-point turning. An increase in feed rate only had a marginal adverse effect on the surface finish due to increased burnishing action between the tool and the workpiece during rotary cutting. Surface finish improved by reducing inclination angle which leads to a corresponding increase in the effective nose radius of the round cutting tool.