SR200
Specifications subject to change
1.2
Note: almost all parameters are defined over one sample length, however in practice more than one sample
length is assessed (usually five) and the mean calculated. This provides a better statistical estimate of the
parameters measured value.
Parameter Definitions
Surface texture is quantified by parameters which relate to certain characteristics of the
texture. The SR200 offers the following parameters:
Ra, Rp, Rsm, Rz, Rt, Rmr, RPc, Rz1max, Rsk, Rda
Additional parameters can be analysed by downloading results to optional software.
Ra:
Universally recognised, and most used, international parameter of roughness. It is the
arithmetic mean of the absolute departures of the roughness profile from the mean line.
Rp:
Maximum profile peak height
Mathematically, the largest peak deviation of the roughness profile from the mean line within a
sampling length.
When more than one sampling length is analysed rp is the mean value of the individual rp
values for each sample.
RSm:
The mean spacing between profile peaks at the mean line, measured within the
sampling length. (A profile peak is the highest point of the profile between an upwards and
downwards crossing of the mean line).
Rz:
Rz = Rp + Rv and is the maximum peak to valley height of the profile within a sampling
length.
When more than one Sampling Length is analysed Rz is the mean value of the individual Rz
values for each Sampling Length.
Rz1max:
Maximum Height of Profile
Highest peak to valley within a sampling length. When measured over several sampling lengths
the largest individual sampling length value is taken.
Also known in the past as Rymax, Ry, Rmax or Rti
Rt:
Total Height of the Profile.
Maximum Peak to Valley Height of the Profile in the Assessment (evaluation) Length (ln).
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