HEIDENHAIN TNC 640 (34059x-02) - Manual (Page 357)

Miscellaneous functions for path behavior 10.4
10
TNC 640 | User's Manual
HEIDENHAIN Conversational Programming | 5/2013
357
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.
Caution: Danger to the workpiece and tool!
On very small outside corners the TNC may increase
the feed rate so much that the tool or workpiece can
be damaged. Avoid
M109 with small outside corners.
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.
If you define M109 or M110 before calling a
machining cycle with a number greater than 200, the
adjusted feed rate is also effective for circular arcs
within these machining cycles. The initial state is
restored after finishing or aborting a machining cycle.
Effect
M109 and M110 become effective at the start of block. To cancel
M109 or M110, enter M111.