Xk10 Straightness Analysis Explained - Renishaw XK10 Manual

XK10 Hardware XK10 Software
Flatness Level
Appendix C: XK10 straightness analysis explained
Deviations from the average
Average level
This is the average deviation along an axis.
Standard deviation (STD) and straightness RMS (root mean squared)
Standard deviation (STD) and straightness RMS both represent the amount
of deviation/spread from the average. Although they are calculated differently,
they both represent the uniformity of straightness, i.e. the smaller the RMS or
STD, the better the straightness. Therefore, an axis with a very small STD or
RMS would be considered very 'straight'.
RMS is a common statistic used for surface roughness, while STD is a
standard statistic for general deviation.
Vertical straightness
0
-0.001
Average
-0.002
-0.003
-0.004
-0.005
-0.006
0 100 200 300
Measurement position (mm)
156 XK10 alignment laser system
XK10 Applications Straightness
Parallelism Coaxiality
400 500 600 700 800
Squareness
Spindle direction
Deviations between points
Waviness
Waviness is used to show if there are any sudden changes or sharp spikes
between points. It is a measure of change between points.
This is useful for machines where smooth transitions are very important.
Unlike STD and RMS, waviness ignores the general straightness deviation
along the axis, and is only concerned with deviations between points.
Straightness results with varying waviness
12
10
8
6
4
2
0
-2
-4
900 0 2
Small waviness
Max waviness
4 6 8 10 12
Sample number
Big waviness
www.renishaw.com/xk10
14 16