Most quality professionals working with surface texture/roughness are well familiar with “R” parameters, such as Ra (average roughness). These widely used parameters are derived from 2-dimensional measurements, typically generated by stylus instruments or other 2D measurement technologies.
Confusion may arise when someone begins working with a new instrument or process that requires the use of “S” parameters, which are specific to areal (3D) measurements. This article gives some background into these two sets of parameters and discusses some of the important differences that may arise when transitioning from using one set to the other.
Michigan Metrology’s article, “Surface Roughness Texture: Considerations when Making the Change from R Parameters to S Parameters,” appears in the April 2021 issue of Finishing and Coating Magazine.