Statistical behaviour of surface profiles

Since the surface profiles obtained by stylus instruments may be considered as a random process, it is possible to represent these profiles by statistical parameters and functions. The usual geometrical parameters from surface profiles used for the specification of roughness do not completely give the nature of the profile. To obtain a better comparison of the profiles, their statistical similarities may be studied, but the number of such parameters used for the specification of surface profiles should, however, be limited for practical applications. Use of the autocorrelation functions allows the periodic and random nature of the profile to be established, but a simple quantitative value for these functions has yet to be developed. The paper analyses a few statistical parameters obtainable from surface profiles to determine their real significance. An analysis of the statistical behaviour of the profile features is also included. © 1971.