Characterizing Surface Quality: Why Average Roughness (Ra) is not Enough

Author: Roger Posusta
Wednesday, September 11, 2024
Bruker Nano Surfaces

Quantification of surface finish is both complex and necessary. Despite surface topography being three-dimensional, the most established surface measurement parameter is average roughness (Ra), a two-dimensional parameter. Ra is easy to measure and can be compared with historical data, but does nothing to describe a surface’s nuances or potential functionality. This application note explores the impacts of using 3D parameters to provide greater insight into surface finish and performance, including two case studies where the use of 3D parameters guided the design and development of high-performance surfaces. Through example and technical explanation, this application note explains 3D measurement parameters (known as S Parameters), what the measurements represent and how the values can be applied to predict surface performance on parts and components.