HEIDENHAIN ND 920 - Manual (Page 50)

50
Multipoint Axis Error Compensation
Multipoint Axis Error Compensation
If you want to use the multipoint axis error
compensation feature, you must
• activate this feature with operating parameter P40
(see "Operating Parameters")
• traverse the reference marks after switching on the
display unit
• enter compensation value table
Your machine may have a non-linear axis error due to factors
such as axis sag or drivescrew errors. Such deviations are
usually measured with a comparator measuring system (such
as the HEIDENHAIN VM 101).
For example, you can determine the screw pitch error X=F(X)
for the X axis.
An axis can only be corrected in relation to one axis that has
an error. In each axis, a compensation value table with
64 compensation values can be generated. You can select the
compensation value table with the MOD key and the dialog
"CODE NUMBER".
All necessary entries for multipoint error compensation are
requested in dialogs.
Entries in the compensation value table
• Axis to be corrected: X, Y or Z (Z axis only with
ND 960 or NDP 960)
• Axis causing the error: X, Y or Z (Z axis only with
ND 960 or NDP 960)
• Datum for the axis to be corrected:
Here you enter the point starting at which the axis with
error is to be corrected. This point indicates the absolute
distance to the reference point.
Do not change the datum point after measuring the
axis error and before entering the axis error into the
compensation table.
• Spacing of the compensation points
The spacing of the compensation points is expressed as
2
x
[µm].
Enter the value of the exponent x into the compensation
value table.
Minimum input value: 6 (= 0.064 mm)
Maximum input value: 20 (= 1048.576 mm)
Example: 600 mm traverse and 35 compensation points:
results in 17.143 mm spacing between points.
Nearest power of two: 2
14 [µm] = 16.384 mm
Entry in compensation value table: 14
• Compensation value
You enter the measured compensation value (in
millimeters) for the displayed compensation point.
Compensation point 0 always has the value 0 and
cannot be changed.