The Material Ratio, mr, is the ratio of the intersecting area of a plane (i.e., parallel to the mean plane) passing through the surface at a given height to the cross sectional area of the evaluation region. The Areal Material Ratio Curve (aka Bearing Area Curve or Abbot Firestone Curve) is established by evaluating mr at various levels from the highest peak to the lowest valley.
Prior to establishing the Areal Material Ratio Curve, a certain percentage of the peak points (i.e., the Peak Offset) and valley points (i.e., the Valley Offset) are eliminated to minimize the effects of outliers. Typically the Peak Offset and Valley Offset are set to 1%, unless otherwise specified. mr is also referred to as “Percent Data Cut.”
Areal Material Ratio Curve and evaluation of mr. Note that the profiles is shown above for simplicity. When evaluating the 3D (Areal) parameters the analysis applies to the complete 3D dataset.