Siemens SINUMERIK 840D Manual page 71

Key functions for 5-axis machining
2
.
Programming
FFWON/
FFWOF
BRISK
SOFT
© Siemens AG All rights reserved. SINUMERIK, Manual, 5-axis machining
. Feedforward control.
In cases where axes are not feedforward-con-
trolled, the following error results in a contour
error whose severity is determined by the
velocity.
in the form of a narrowing of the radius
curved contours. The following error depends
on the servo gain factor that is set (dependent
3
on mechanics) and the axis velocity.
1
The FFWON feedforward control function
brings the velocity-dependent following error
down towards zero during path traversal. Tra-
versing with feedforward control permits
.
higher path accuracy and thus improved
machining results.
.
. Recommendations
CYCLE832 includes the following combina-
tions:
.
FFWON SOFT
The emphasis is on a high path accuracy. This
is achieved using a soft form of velocity control
that is essentially free from following errors.
FFWOF SOFT
The priority is not on achieving a high path
accuracy.
Additional rounding is achieved by means of
following errors. For use with older part pro-
grams/machines.
FFWON BRISK
Not recommended
FFWOF BRISK
For use when roughing and when maximum
velocity is required.
3.6
1 . Generally, this will manifest itself
on
3
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