Brütsch Rüegger 148 460, Manual

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10 - 21
No. 99MBB079A
10. REFERENCE INFORMATION
10.5.9 Mean width of the profile elements, Sm (JIS, ISO, DIN)
A portion projecting upward over the given upper count level is called a peak, and a portion
projecting downward below the given lower count level is called a valley. The mean of the
profile element (profile peak and the adjacent profile valley) widths within a sampling length
is defined as Sm.
n
i=1
Sm =
1
n
Smi
∑
Count level
Sm1 Smi Smn
Count level
*
*
Dead zone equidistant about the mean line.
●
The following restrictions are provided to determine a profile element:
• Peaks and valleys must appear alternately.
• The intersection of the assessed profile with the mean line immediately before the profile
element is the start point of it and is the end point of the previous profile element.
• At the start point of the sampling length, however, if either the peak or valley is missing,
the profile element width is not taken into account.
●
For ANSI, Sm is defined over the evaluation length.
10.5.10 Peak count, Pc (JIS, ISO, DIN)
The reciprocal of the mean width of the profile elements, Sm, is “Pc”.
Pc = Unit length/Sm (Unit length = 1 cm or 1 inch)
●
For ANSI, Pc is defined over the evaluation length.