A new procedure for characterizing textured surfaces with a deterministic pattern of valley features

Abstract

In recent years there has been the development of a high number of manufacturing methods for creating textured surfaces which often present deterministic patterns of valley features. Unfortunately, suitable methodologies for characterizing them are lacking. Existing standards cannot in fact properly characterize such surfaces, providing at times unreasonable values. In this paper, a new procedure for characterizing such surfaces is proposed, relying on advanced filtering and feature recognition and separation. Existing advanced filtering methods do not always eliminate all distortions, therefore some modifications are investigated. In particular the robust Gaussian regression filter has been modified providing an envelope first-guess in order to always fit the mean line through the plateau region. Starting from a filtered and aligned profile, the feature thresholds recognition and separation is therefore made possible. In particular the plateau and valley regions can be detected, separated and independently analyzed according to their function. The example of a multifunctional profile is presented. The profile is analyzed using the new procedure, which demonstrates outputting a correctly aligned roughness profile and permitting comprehensive feature analyses.

Distinguishing the Plateau and Valley Components of Profiles From Various Types of Two-Process Textures

“…Godi et al determined the lower threshold as 25−50% of the total profile height from the lowest profile point depending on irregularity of the valley distribution [22,23]. We propose a different method of determining this threshold.…”

“…As a result of this procedure, a correct plateau separation is achieved. The details are given in [22,23]. This approach can be promising also for two-process profiles of a random character.…”

“…A problem arises in determining the lower threshold. Godi et al [22,23] recommended a special procedure for random-deterministic two-process surfaces.…”

“…It is rotated counter-clockwise by an angle being the slope of the line passing through the first and last points of the material probability curve, then the point of the maximum ordinate of this curve can be treated as the plateau-valley transition point [27]. Godi et al [22,23] modified marginally this method. In their proposal the transition point has the largest perpendicular distance to the straight line connecting the first and finishing points of the material probability curve.…”

“…In their proposal the transition point has the largest perpendicular distance to the straight line connecting the first and finishing points of the material probability curve. The lubrication capability of valleys was evaluated on the basis of a new parameter called EQF (equivalent film thickness), being the ratio of the linear volume of oil pockets and the profile evaluation length [22,23].…”