HEIDENHAIN TNC 410 - Manual (Page 128)

115 HEIDENHAIN TNC 410
7.
4 Miscellaneous F
unctions f
or Cont
our
ing Beha
vior
Constant feed rate at the tool cutting edge: M109/
M110/M111
Standard behavior
The TNC applies the programmed feed rate to the path of the tool
center.
Behavior at circular arcs with M109
The TNC adjusts the feed rate at inside and outside contours such
that the feed rate at the tool cutting edge remains constant.
Behavior at circular arcs with M110
The TNC keeps the feed rate constant at inside contours only. At
outside contours, the feed rate is not adjusted.
Effect
M109 and M110 become effective at the start of the block.
To cancel M109 or M110, enter M111.
Calculating the radius-compensated path in advance
(LOOK AHEAD): M120
Standard behavior
If the tool radius is larger than the contour step that is to be
machined with radius compensation, the TNC interrupts program
run and generates an error message. Although you can use M97 to
inhibit the error message (see “Machining small contour steps:
M97”), this will result in dwell marks and will also move the corner.
If the programmed contour contains undercut features, the tool
may damage the contour. —See figure at right.
Behavior with M120
The TNC checks radius-compensated paths for contour undercuts
and tool path intersections, and calculates the tool path in advance
from the current block. Areas of the contour that might be damaged
by the tool, are not machined (dark areas in figure at right). You can
also use M120 to calculate the radius compensation for digitized
data or data created on an external programming system. This
means that deviations from the theoretical tool radius can be
compensated.
Use LA (Look Ahead) behind M120 to define the number of blocks
(maximum: 99) that you want the TNC to calculate in advance. Note
that the larger the number of blocks you choose, the higher the
block processing time will be.
X
Y