Effects of tool wear on surface micro-topography in ultra-precision turning

In ultra-precision turning of large optical components, the surface quality deterioration caused by tool wear has severely restricted the optical performance of these components. To investigate the effects of tool wear on surface micro-topography, this paper conducts an experimental study on the ultra-precision turning of copper. The wear characteristics of the diamond tool and the micro-topography of the ultra-precision turned surface at different cutting distances are discussed and evaluated. The plastic deformation behavior of the workpiece material is investigated at various cutting parameters and tool wear conditions. Furthermore, the power spectral density (PSD) and the diffraction optical characteristics of the machined surface are achieved and analyzed quantitatively. The experimental results show that during diamond turning of copper, the tool wear is mainly characterized by the micro-breakages on the tool edge when the cutting distance is less than 24km. With the increase of the cutting distance, the micro-breakages gradually develop into the continuous wear land, and the enlarged wear area is attributed to the cumulative cleavage fractures and uniform mechanical wear. Moreover, the increased tool wear can result in more pronounced periodic surface micro-topography and greater height of the material pile up, which will deteriorate the optical performance and enhance the diffraction effect of the ultra-precision turned surface.