HEIDENHAIN ND 100 User Manual - Manual (Page 81)

ND 120 QUADRA-CHEK 81
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p Error correction
There are three error correction methods:
 LEC: Linear Error Correction
 SLEC: Segmented Linear Error Correction
 NLEC: Nonlinear Error Correction
All DRO models are equipped with LEC, SLEC and NLEC. Each
method compensates for encoder and machine travel variations with
error correction coefficients. Coefficients are determined by
comparing actual measurements of a standard to the nominal values
imprinted on it.
Linear error correction (LEC) is performed in the LEC setup screen
and compensates for variations along an axis using one correction
coefficient for the entire range of motion on the axis. For example, an
LEC coefficient of 0.0002 per inch applied to a 6 inch measurement
along an axis produces a result of 6.0012 inches.
Segmented linear error correction (SLEC) is performed in the SLEC
setup screen and compensates for variations along an axis by applying
correction values to several individual segments of the measurement
range. The use of multiple segments increases the accuracy of
measurements beyond the accuracy obtained by applying a single
(average) to the entire axis. The correction starting point is mapped to
the axis machine zero MZ Offset) so that the correction coefficients
can be applied to each segment location upon power up.
Nonlinear error correction (NLEC) is performed in the NLEC setup
screen and compensates for variations in the entire measurement
plane created by two axes by applying correction values to a grid of
small areas included by the plane. The correction starting point for
NLEC is mapped to the machine zeroes of the two axes (MZ Offset)
so that the correction coefficients can be accurately applied to each
grid area location upon power up.
NLEC can be performed using one of two methods:
 By measuring points on a certified calibration grid with the target
ND 12x system
 By loading correction data from an NLEC data set generated by
another ND 12x or other systems capable of generating NLEC data.
Notice
A repeatable machine zero, established by crossing
reference marks or defining a manual hard-stop, must be
present prior to performing SLEC or NLEC procedures.