Six-directional pseudorandom consecutive unicursal polishing path for suppressing mid-spatial frequency error and realizing consecutive uniform coverage

Planning the polishing path is an important part of the polishing process. Reasonable selection of the polishing path can improve surface quality and reduce the mid-spatial frequency (MSF) error. In this paper, a six-directional pseudorandom consecutive unicursal polishing path and the corresponding generation method are proposed. The proposed path is especially useful for suppressing the MSF error of the surface and realizing consecutive uniform coverage. Compared with traditional polishing paths such as scanning, spiral, and fractal, the proposed path has the following characteristics: multi-directionality, high randomness, smoothness, and consecutiveness. In order to verify that the proposed path has the ability to suppress the MSF error, a group of contrast experiments were conducted and the measurement data was processed by the empirical mode decomposition (EMD) method and the fast Fourier transform (FFT) method. The results show that the fluctuation amplitude of the MSF error and the fluctuation area with MSF error are obviously reduced by using the proposed path. Moreover, the corresponding wavelength of the crests in the spectrum shows multi-values. The experimental results show that the proposed path has high randomness and the ability to suppress the MSF error.