3D surface measurement (three-dimensional surface measurement) is used by both the industrial sector and scientific community to drive the success of critical research projects, crucial developments, and fundamental productions and process controls. The 3D surface measurement parameters (S parameters) were defined in 1991 by the attendees of the first EC Workshop and have since been developed in accordance with ISO standards to complement the traditional 2D (two-dimensional) metrology R parameters.
Much of the early work to develop standard, worldwide 3D surface measurement parameters was completed by a European consortium. Their work resulted in four general categories: amplitude, spatial, hybrid and functional.
The amplitude parameters are based on overall heights and include the root-mean-square of height distribution, skewness (or the degree of asymmetry of a surface height distribution), the degree of peakedness of a surface height distribution (or kurtosis), and an average of the highest and lowest points.
Spatial parameters are based on frequencies of features and include the texture direction of a surface, texture aspect ratio, and the density of summits.
Based on a combination of height and frequency, the hybrid parameters include the mean summit curvature, developed surface area ratios, and the root-mean-square of surface slopes.
Finally, the functional parameters include several parameters that are based on applicability of particular functions.
The initial resistance to using the techniques of 3D surface measurement was eventually overcome as R&D engineers took the time to fully understand the advantages of three-dimensional surface analysis and a shift became apparent as the S parameters were employed on more and more drawings and suppliers were being held to those specifications.
It was found that 3D surface parameters helped to improve communication and allowed a process control that traditional R parameters could not do alone.
Surfaces with similar or even identical average surface roughness values (Ra) might have vastly different surface topographies. In order to better quanitify and differentiate these types of surfaces, industries have begun to develop three-dimensional (3D) standards.
Modern 3D surface measurement has given engineers, process designers, and quality control professionals a significantly improved toolkit for describing surfaces since three-dimensional measurements uniquely differentiate not only surface shapes but functionalities as well. All of which, ultimately, results in better surface performance.