K3: Compensations
4.6 Friction compensation (quadrant error compensation)
Extended Functions
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
287
4.6 Friction compensation (quadrant error compensation)
4.6.1 General function description
In addition to the mass inertia and the machining forces, the frictional forces in the gearing
and guideways of the machine influence the behavior of a machine axis. During the
acceleration of an axis from standstill, especially the transition from static friction to the
significantly smaller sliding friction has a negative affect with regard to the contour accuracy.
The sudden change in the friction force results in a briefly increased following error. With
interpolating axes (path axes), this results in significant contour violations. For circles, the
contour violations occur especially at the quadrant transitions due to the standstill of one of
the involved axis at the direction reversal.
Therefore, an additional setpoint pulse is injected as a compensation value for this friction or
quadrant error compensation when the axis accelerates from standstill, i.e. at the transition
from static to sliding friction. In this way, contour violations can be almost completely avoided
at the quadrant transitions of circular contours.
Acceleration-dependent friction compensation
In most cases, a compensation value independent of the axial acceleration with constant
amplitude is sufficient for the quadrant error compensation. However, if the compensation
value is dependent on the acceleration, an adaptation characteristic can be activated via the
"friction compensation with adaptation" in order to model this behavior.
Circularity test
The easiest way to commission the friction compensation is with the circularity test
integrated in the user interface. A circle is traversed and the circular contour generated on
the machine based on the actual position values of the involved machine axes and the
deviations to the programmed ideal circular contour, especially at the quadrant transitions,
displayed in graphical form.
The circularity test can be found on the user interface under:
SINUMERIK Operate
"Operating area switchover" > "Commissioning" > "Optimization/test" > "Circularity test"
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