## Material Ratio Curve (Bac)

Material ratio curve shows the curve of load length ratio determined as the cut level c function.

Load length ratio is the ratio (%) obtained by dividing the total lengths of the length of curve data exceeding the cut level by the entire length (rn).

The number of data points N is the smaller of 4096 and (maximum height / Z calibration).
Maximum height is divided by (N-1) to get the pitch, which is then used for the cut level.

Each height is assigned BAC (n) as its load length ratio. n = N is the minimum height.

BAC (N) = 100.0, however BAC (0) does not necessarily equal 0.0.

Load length ratio is displayed as a % on the horizontal axis while cut level is displayed on the vertical axis in μm Mil. (Cut height is in the same range as the profile curve graph.)

## Surface Roughness Parameters

This section explains the main parameters of ISO 4287:1997. Each parameter is classified according to primary profile (P), roughness profile (R), and waviness profile (W) in order to evaluate different aspects of the profile. (When the wavelengths of the waviness and primary profile components are compared, the surface roughness component is the asperity component of that which has the comparatively shorter wavelength.)