Siemens SINUMERIK 840C - Manual (Page 239)

6 NC Machine Data (NC MD), NC Setting Data (NC SD) 09.95
6.4 Axis-specific MD 1 (axial data 1)
The NC activates leadscrew error compensation (SSFK) after reaching the reference point.
The CNC must therefore be informed via MD 316* as to which of the 1000 possible
compensation points represents the reference point for the axis in question.
Separate compensation curves for positive and negative traversing movements are available
for direction dependent leadscrew error compensation, necessitating the use of two
compensation pointers (MD 316* for " + " and MD 320* for " - "). The value refers to the
compensation point which corresponds to the reference point (see Section entitled ”Functional
Descriptions”).
Distance between 2 leadscrew error compensation values 324*
Default value Lower input limit Upper input limit Units
0 +0 32 000 units (MS)
Active on
Power On
The distance between two compensation points depends on:
• the permissible tolerance band
• the maximum gradient of the sumcheck error characteristic of the spindle/measuring
system
• the maximum number of compensation points
(See also Section entitled ”Functional Descriptions”).
Leadscrew error compensation value 328*
Default value Lower input limit Upper input limit Units
0 +0 100 units (MS)
Active on
Power On
The compensation value depends on the permissible tolerance band for the axis position. The
value for the tolerance band or a slightly lower value is entered in order to make use of the full
bandwidth for each compensation procedure (also see Section entitled ”Functional
Descriptions” for details on leadscrew error compensation).
The compensation value entered in NC MD 328* must be less than that entered in NC MD
324*. This MD applies both to rotary and linear axes.
Tolerance band for contour monitoring 332*
Default value Lower input limit Upper input limit Units
1 000 +0 99 999 999 units (MS)
Active for all
channels of
mode group
in STOP
The following error is proportional to the speed after acceleration or deceleration (i.e. in the
steady state), so no fluctuations in the following error may develop during travel at constant
speed, as this would result in contour deviations. Minor fluctuations in the following error which
trigger control processes are, however, allowed.
The definition of a tolerance band is intended to prevent false tripping of the contour monitor
due to slight fluctuations in speed caused by normal control processes.
For a detailed description, see Section entitled ”Axis (Analog) and Spindle Installation”.
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SINUMERIK 840C (IA)