The Conditions to Apply the Phase Corrected Filter to Traced Profiles for Roughness Profiles (1st Report)

Application of the Gaussian High-pass Digital Filter

Abstract

The surface roughness parameters in ISO are obtained according to the mean-line system based on the high-pass digital Gaussian filter called the phase-corrected-filter. As the discrete data are used, the transmission characteristics of filter have the error caused by the inadequate range of convolution integral and space of data. This paper deals with an optimum condition of the high-pass digital filter for the roughness profile. The new knowledges of this paper are as follows. (1)The allowable error of transmission characteristics is determined as 2% at the point where the fluctuation of roughness parameters increase radically. (2)The range of convolution integral is given by 0.9 times the cut-off length. (3)The condition applied to the filter by this paper is compared with that recommended by ISO. (4)The roughness parameters by the mean line system differ little from those by the center line system which is a traditional method except S_k and S_m.