HEIDENHAIN iTNC 530 (340 49x-02) ISO programming - Manual (Page 242)

242 7 Programming: Miscellaneous Functions
7.
4 Miscellaneous F
unctions f
o
r Cont
our
ing Beha
vior
Feed rate for circular arcs: 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 for circular arcs at inside and outside
contours so that the feed rate at the tool cutting edge remains
constant.
Behavior at circular arcs with M110
The TNC keeps the feed rate constant for circular arcs at inside
contours only. At outside contours, the feed rate is not adjusted.
Effect
M109 and M110 become effective at the start of block.
To cancel M109 and 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. M97 (see “Machining small contour
steps: M97” on page 237) inhibits the error message, but this results
in dwell marks and will also move the corner.
If the programmed contour contains undercut features, the tool may
damage the contour.
M110 is also effective for the inside machining of circular
arcs using contour cycles. If you define M109 or M110
before calling a machining cycle, the adjusted feed rate is
also effective for circular arcs within machining cycles. The
initial state is restored after finishing or aborting a
machining cycle.
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