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**3D Functional Parameters **

Vv(mr) (Void Volume), Vvv(p) (Dale Void Volume), Vvc(p,q) (Core Void Volume)

**Vv(mr), **the Void Volume**, ** is
the volume of space bounded by the surface texture from a plane at a
height corresponding to a chosen “**mr**” value
to the lowest valley. “**mr**” may be set to
any value from 0% to 100%.

**Vvv(p)**, the Dale Void Volume, is
the volume of space bounded by the surface texture from a plane at a
height corresponding to a material ratio (mr) level, “**p**” to
the lowest valley. The default value for “**p**” is
80% but may be changed as needed.

**Vvc(p,q)**, The Core Void Volume**, **is
the volume of space bounded by the texture at 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%.

Application

**Vv(mr)**, **Vvv(p)** and **Vvc(p,q)** all
indicate a measure of the void volume provided by the surface between various
heights as established by the chosen material ratio(s) values. Thus
these three void volume parameters indicate how much fluid would fill the
surface (normalized to the measurement area) between the chosen material
ratio values. For example, a **Vv(25%)** = 0.5 µm3/µm2 in (note
how the units µm3/µm2 reduce to µm) that a 0.5 µm
thick film over the measurement area would provide the same volume of fluid
as needed to fill the measured surface from a height corresponding to mr=25%
to the lowest valley.

The void volume parameters are useful when considering
fluid flow, coating applications and debris entrapment. A new surface may
be specified by **Vv(0%)** which
would indicate the total initial void volume provided by the texture. The
Core Void Volume , **Vvc,** may be useful to establish how
much core space is available once a surface has been run-in resulting in
decreased peak heights . The Dale Void Volume, **Vvv(p)** may
be useful in indicating the potential remaining volume after significant
wear of a surface has resulted.