EVALUATION OF A SELF-PROPELLED ROTARY TOOL IN THE MACHINING OF AEROSPACE MATERIALS

The self-propelled rotary tool (SPRT) incorporating round-shaped cemen ted carbide cutting inserts exhibits superior wear resistance when mac hining titanium IMI 318 alloy under finishing conditions involving a l ow depth of cut of 0.25 mm. The rotary cutting action extends tool lif e by more than 60 times compared with the rhomboid and round inserts u sed in single-point turning Excessive chipping was the dominant failur e mode when machining IMI 318 with the SPRT due to thermal and mechani cal shocks as well as vibration during machining. When machining nicke l-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 record ed with the SPRT were lower than those obtained during conventional si ngle-point turning. An increase in feed rate only had a marginal adver se effect on the surface finish due to increased burnishing action bet ween 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.