Abstract
Surfaces with different topographies are formed by the various types of manufacturing processes. To express the characteristics of these surfaces, the International Organization for Standardization (ISO) defines two-dimensional (2-D) surface roughness parameters, which are used for geometrical product specification (GPS). 2-D surface roughness parameters are widely used in engineering fields. In contrast, 3-D surface roughness parameters have been standardized with the development of measurement technologies. In the field of tribology, the relationship between the surface roughness parameters and tribological characteristics has been extensively studied. However, surface roughness parameters for the expression of tribological characteristics have not yet been reported. In this research, the fast Fourier transform (FFT) method was applied to evaluate the periodicity of sliding surfaces. Using the 2-D FFT method, the 2-D power spectral density (PSD) was obtained for actual surfaces. The relationships between the 2-D PSDs and the friction characteristics of anisotropic surfaces were examined. From these results, it was determined that all the data from the 2-D PSD are required to determine the optimal direction of sliding. A new 3-D surface roughness parameter to express these relationships was proposed. It was shown that this parameter is able to determine the sliding angle where the lowest or highest friction coefficients are attained for common industrial surfaces. This parameter could be used in the design of sliding surfaces as a GPS parameter to express friction characteristics.
