Vmp(p)
Vm(mr), the Material Volume, is the volume of material comprising the surface from the height corresponding to mr to the highest peak of the surface. “mr” may be set to any value from 0% to 100%.
Vmp(p), the Peak Material Volume, is the volume of material comprising the surface from the height corresponding to a material ratio level, “p”, to the highest peak. The default value for “p” is 10% but may be changed as needed.
Vmc(p,q), the Core Material Volume, is the volume of material comprising the texture between heights corresponding to the material ratio values of “p” and “q”. The default value for “p” is 10% and the default value for “q” is 80% but may be changed as needed.
Note: The units for the Vv(mr), Vv(p) and Vvc(p,q) are µm3/µm2 – the void volume normalized by the cross sectional area of the measurement area. The peak offsets and valley offsets are applied prior to analysis.
Application
Vm(mr), Vmp(p) and Vmc(p,q) all indicate a measure of the material forming the surface at the various heights down from the highest peak of surface or between various heights as defined for Vmc(p,q).
For example, a Vm(10%) =0.35µm3/µm2 would indicate (note how the units µm3/µm2 reduce to µm) that a layer 0.35µm thick of material over the measured cross section would account for all the material from the highest peak to the 10% point on the bearing area curve.
The various Material Volume parameters are useful to understand how much material may be worn away for a given depth of the bearing curve (i.e. Vmp(p)) and how much material is available for load support once the top levels of a surfaces are worn away (i.e. Vmc(p,q)). For sealing applications, Vmp(p) may provide insight into the amount of material available for seal engagement whereas Vvc(p.q) (see above) may then provide information about the resulting void volume for fluid entrapment or leakage.