Mitutoyo SJ-301 - Mean Spacing of Local Peaks of Profile, S; Developed Profile Length lo

14 - 30 No. 99MBB091A
14.5.31 Mean spacing of local peaks of profile, S
S is the arithmetic mean of peak-to-peak distances of the local peaks. For the ANSI standard,
S is obtained over the evaluation length.
n
i=1
S =
1
n
Si
∑
S1 Si Sn
● Local peaks
If an upward convex portion of an assessed profile has concavities on both sides, the
highest point of the convex portion is called a local peak. However, if the distance (in the
sampling direction) between adjacent convexities is less than 1% of sampling length l, or if
the depth of the concavities is less than 10% of Ry, the convex portion does not qualify as
a local peak.
Ry
10
or more
Ry
10
or more
ᐉ
100
or more
ᐉ
100
or more
Local peak
14.5.32 Developed profile length Lo
If an assessed profile has developed into a line without profile irregularities, the line length
Lo is given by the following formula.
N
i=1
Lo = Yi +X
∑
22
1
2