Mitutoyo SURFTEST SJ-410 - Motif-Related Parameters; How to Obtain Roughness Motifs

23. REFERENCE INFORMATION
No. 99MBB765A
23-39
23.6 Motif-related Parameters
The motif method is a French standard for evaluating surface roughness. This method
was adopted as an ISO standard (ISO12085-1996) in 1996.
Normally, when wave segments are removed from an evaluation profile, the evaluation profile
becomes distorted. This method is designed to remove waviness without causing distortion.
With this method, an evaluation profile is divided into units called “motifs”, which are based on
the wavelength of a component to be removed, and parameters to evaluate the profile are
calculated from each motif. This chapter briefly explains how to obtain the motif parameters.
23.6.1 How to obtain roughness motifs
Use the following procedure to obtain roughness motifs.
1. In order to prevent small bumps from influencing the procedure, obtain the minimum
height (Hmin) used to determine peaks.
Divide the evaluation data into segments that are half the length of the
roughness-motif maximum length, A. For each segment, determine the distance
between the maximum point and the minimum point, and set the minimum height as
5% of the average of these distances.
Minimum height for determining a peak
∑
=
×
=
n
i
hi
n
H
1
1
05.0
min
n: Number of segments
2. Obtain all of the peaks and valleys for the entire evaluation length.
Peaks are defined as the highest point between two valleys whose height is Hmin or
greater. Valleys are the lowest point between two peaks. These peaks and valleys will
be used for the entire evaluation length.
Peak, valley
A/2
h
1
h
n
P
P
P
P
V
V
V
V
H
min
P: Peak
V: Valley