Structural coloration using face turning and variable tool vibration frequency

Abstract The technique of manufacturing surface micro-/nano- structures to colorize metal surfaces by using elliptical vibrating cutting has been continuously developed and has good industrial potential. However, the image rendering is based on a raster scan path and constant variation of cutting velocity. The process efficiency and stability are significantly restricted. In this study, a new approach is proposed to implement the elliptical vibration texturing in a face turning setup, where the image rendering is achieved by an equidistant spiral tool path and modulation of the tool vibration frequency. The basic principle is that, while moving at a constant surface velocity, the tool follows a variable frequency elliptical vibration to machine gratings with different spacings on the workpiece surface. In order to ensure the uniformity in the radial direction and the consistency of the color under the same frequency excitation, a smoothly accelerated equidistant spiral tool path is designed. In addition, since the running speed of the machine tool is not completely synchronized with the signal of the tool vibration, a compensation method through the pre-experimental calibration test is proposed. The machining test on the ultra-precision lathe is performed. It is found that on the compensated machined image, cumulative errors caused by the asynchronous operation of the lathe and vibration tool are eliminated, which validates the feasibility and effectiveness of the method.