Roughness testers are used to measure surface roughness, and their parameters reflect the microscopic geometric characteristics of the surface.
The following are common parameters and their meanings:
- Ra (arithmetic mean roughness)
Definition: The arithmetic mean of the absolute value of the profile deviation.
Meaning: Indicates the overall level of surface roughness. The larger the value, the rougher the surface. - Rz (average peak-to-valley height)
Definition: The average height difference between the five highest peaks and the five lowest valleys within the sampling length.
Meaning: Reflects the degree of fluctuation of the peaks and valleys of the surface. The larger the value, the more obvious the fluctuation. - Rq (root mean square roughness)
Definition: The root mean square value of the profile deviation.
Meaning: Indicates the degree of discreteness of the surface roughness. The larger the value, the more uneven the surface. - Ry (maximum height)
Definition: The vertical distance between the highest peak and the lowest valley of the profile within the sampling length.
Meaning: Reflects the maximum fluctuation of the surface. The larger the value, the more uneven the surface. - Rsk (skewness)
Definition: The degree of skewness of the profile height distribution.
Meaning: Positive skew indicates more peaks, negative skew indicates more valleys, and zero indicates symmetrical distribution. - Rku (kurtosis)
Definition: The sharpness of the profile height distribution.
Meaning: A value greater than 3 indicates a sharper distribution, and less than 3 indicates a flatter distribution. - Rsm (average width of profile unit)
Definition: The average width of the profile unit.
Meaning: Reflects the density of the surface texture. The larger the value, the sparser the texture. - Rmr (profile support length ratio)
Definition: The ratio of the profile support length to the sampling length.
Meaning: Represents the surface support capacity. The larger the value, the stronger the support capacity. - Rc (average height of profile unit)
Definition: The average height of the profile unit.
Meaning: Reflects the average height of the microscopic undulations of the surface. The larger the value, the more obvious the undulations. - Rmax (maximum profile height)
Definition: The vertical distance between the highest peak and the lowest valley of the profile within the evaluation length.
Meaning: Reflects the maximum undulation of the surface. The larger the value, the more uneven the surface. - Rpm (average profile peak height)
Definition: the average height of each profile peak within the sampling length.
Meaning: reflects the average height of the surface peaks. The larger the value, the higher the peak. - Rv (maximum valley depth)
Definition: the lowest valley depth of the profile within the sampling length.
Meaning: reflects the maximum valley depth of the surface. The larger the value, the deeper the valley. - Rz1max (maximum single peak height)
Definition: the maximum height of a single profile peak within the sampling length.
Meaning: reflects the height of the highest peak on the surface. The larger the value, the higher the peak. - Rz1min (minimum single peak height)
Definition: the minimum height of a single profile peak within the sampling length.
Meaning: reflects the height of the lowest peak on the surface. The smaller the value, the lower the peak. - RzJIS (Japanese Industrial Standard Roughness)
Definition: the average peak-to-valley height calculated according to the JIS standard.
Meaning: reflects the average height of the peaks and valleys on the surface. The larger the value, the rougher the surface.
These parameters describe surface roughness from different perspectives, and selecting appropriate parameters helps to accurately evaluate surface quality.
