3D Surface Roughness and Wear Measurement, Analysis and Inspection

Inverse Areal Material Ratio


The Inverse Areal Material ratio, Sdc(mr) is the height, c, which gives the specified material ratio, mr. The height c may be measured from the best fitting least squares mean plane or as a depth down from the maximum point of the Areal Material Ratio Curve.


Sdc(mr) might be used to assure that an optimum crevice volume is produced for a sealing surface to allow for some lubricant entrapment (to prevent running dry) but not be too deep to prevent leakage. For example, a specification such as -0.4 um <Sdc(100%)<-0.8 µm with a 1% peak and 1% valley offset, measured from the mean plane, would assure that the bottom 50% or the surface would extend at least 0.4 um below the mean plane but no greater than 0.8µm.