HEIDENHAIN TNC 620, User Manual

Page: 294 / 521

Testing and running | Running CAM programs
6
Please note the following for CAM programming
Adapting chord errors
Programming notes:
For finishing operations, do not set the chord error
in the CAM system to a value greater than 5 μm. In
Cycle
32
, use an appropriate tolerance factor
T
of 1.3
to 3.
For roughing operations, the total of the chord error
and the tolerance
T
must be less than the defined
machining oversize. In this way you can avoid contour
damage.
The specific values depend upon the dynamics of your
machine.
Adapt the chord error in the CAM program, depending on the
machining:
Roughing with preference for speed:
Use higher values for the chord error and the matching tolerance
value in Cycle
32
. Both values depend on the oversize required
on the contour. If a special cycle is available on your machine,
use the roughing mode. In roughing mode the machine generally
moves with high jerk values and high accelerations
Normal tolerance in Cycle
32
: Between 0.05 mm and 0.3 mm
Normal chord error in the CAM system: Between
0.004 mm and 0.030 mm
Finishing with preference for high accuracy:
Use smaller values for the chord error and a matching low
tolerance in Cycle
32
. The data density must be high enough for
the control to detect transitions and corners exactly. If a special
cycle is available on your machine, use the finishing mode. In
finishing mode the machine generally moves with low jerk values
and low accelerations
Normal tolerance in Cycle
32
: Between 0.002 mm and
0.006 mm
Normal chord error in the CAM system: Between
0.001 mm and 0.004 mm
Finishing with preference for high surface quality:
Use small values for the chord error and a matching larger
tolerance in Cycle
32
. The control is then able to better smooth
the contour. If a special cycle is available on your machine, use
the finishing mode. In finishing mode the machine generally
moves with low jerk values and low accelerations
Normal tolerance in Cycle
32
: Between 0.010 mm and
0.020 mm
Normal chord error in the CAM system: Approx. 0.005 mm
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HEIDENHAIN | TNC 620 | User's Manual for Setup, Testing and Running NC Programs | 01/2022