Generation mechanism of irregular microstructures on the machined surface in single-point diamond turning.

Polycrystalline copper is widely applied to the manufacture of optical components. Our previous experiments found that some irregular microstructures appeared on the machined surface; however, it had lacked sufficient studies about generation mechanism. The present research conducted a theoretical and experimental study on the generation mechanism of irregular microstructures. Firstly, the appearance and distribution of irregular microstructures on the machined surface was studied. Secondly, the effects of crystal orientations on the generation of irregular microstructures were investigated. Finally, the cutting performances were investigated by both molecular dynamics simulations and experiments. Theoretical and experimental results show that (1) material properties under different grain orientations are the major cause of the appearance of irregular microstructures; (2) with the changes of crystal orientations, the force signal, chip morphology, shear slip of material, and subsurface defect are also different; and (3) higher cutting velocities have the suppression effect on the generation of irregular microstructures. The present research provides a deep insight into the generation mechanism and suppression method of irregular microstructures in single point diamond turning polycrystalline copper. [ABSTRACT FROM AUTHOR]