Experimental investigation of the three-component forces in finish dry hard turning of hardened tool steel at different hardness levels

In this paper, the effects of cutting speed, depth of cut, feed, workpiece hardness (51, 55, 58, 62, and 65?±?1 HRC), tool flank wear, and nose radius on three-component forces in finish dry hard turning (FDHT) of the hardened tool steel AISI D2 were experimentally investigated by utilizing the PCBN inserts. Experimental results showed that the feed force is the lowest in three-component forces and influence of cutting parameters on it is less than two others in the FDHT of AISI D2. Values of the radial force are higher than those of the cutting force when cutting speed, depth of cut, and feed range from 75 to 301 m/min, and 0.10 to 0.40 and 0.05 to 0.20 mm, respectively, but lower in the range between 0.8- and 1.6-mm nose radius. Values of the cutting force are higher than those of the radial force as the workpiece hardness varies from 51 to 58?±?1 HRC while lower in the range between 62 and 65?±?1 HRC. Besides, there are relations between the changing laws of three-component forces and the softening effect of chip, cohesion effect in the tool–chip junction zone, and intenerating effect of metal in the workpiece surface. The high flank wear formation increases the contact with workpiece surface and hence induces tearing–drawing and welding effect duo to instantaneous high temperature.