Download a PDF version of this Glossary

**2 D (Profile) Stylus Parameters**

**Stylus (X, Y)
Ra, Rt, Rz**

**Stylus X Ra **and **Stylus Y Ra , **the
Average Roughness Along X and the Average Roughness Along Y, are
found from the integral of the profiles along the respective directions:

**Stylus (X, Y) Rt**, the Maximum Profile
Height Along (X,Y),
is determined from the difference between the highest peak and lowest
valley found along the __evaluation__ length.

**Stylus (X,Y) Rz, **the Average
Maximum Profile Height Along (X,Y), is derived from the
average, over all cutoff lengths (i.e. sampling lengths), of the difference
between the highest peak and lowest valley. Note, if the evaluation length
equals the sampling length then the Stylus (X.Y) Rt and Stylus (X,Y) Rz
values are equal.

Note that the value reported in the database is
the average of all **Stylus (X,Y)** **Ra**, **Rt**, **Rz** values
found over the 400+ profiles that comprise the 3D surface in the relevant
direction.

Application

**Stylus (X,Y)** (**Ra**, **Rt**, **Rz)** may
be useful in understanding any directionally dependent surface texture function.
For example, a surface used for sealing may require a larger roughness average
along the leak path direction (e.g. the X direction) and lower roughness average
perpendicular (e.g. the Y direction) to the leak path for proper seal engagement.