Siemens SINUMERIK 840D sl Function Manual page 73

Very pointed outside corners
Where outside corners are very pointed, G451 can result in excessive idle paths. Therefore, the
system switches automatically from G451 (intersection) to G450 (transition circle, with DISC
where appropriate) when outside corners are very pointed.
The threshold angle (contour angle) for this automatic switchover (intersection point →
transition circle) can be specified in the machine data:
MD20210 $MC_CUTCOM_CORNER_LIMIT (Max. angle for compensation blocks with tool
radius compensation).
Figure 2-17
Very flat outside corners
Where outside corners are very flat, the response with G450 (transition circle) and G451
(intersection) becomes increasingly similar. In this case, it is no longer advisable to insert a
transition circle. One reason why it is not permitted to insert a transition circle at these outside
corners with 5-axis machining is that this would impose restrictions on speed in contouring
mode (G64). Therefore, the system switches automatically from G450 (transition circle,
with DISC where appropriate) to G451 (intersection) when outside corners are very flat.
The threshold angle (contour angle) for this automatic switchover (transition circle →
intersection point) can be specified in the machine data:
MD20230 $MC_CUTCOM_CURVE_INSERT_LIMIT (Max. angle for intersection calculation
with tool radius compensation).
Tools
Function Manual, 06/2019, A5E47435126B AA
Example of automatic switchover to transition circle
W1: Tool offset
2.5 2D tool radius compensation
73