Siemens SINUMERIK 840D sl Programming Manual page 297

Traversing behavior
When G450 is activated and with acute contour angles and high DISC values, the tool is lifted
off the contour at the corners. In the case of contour angles equal to or greater than 120°,
there is uniform travel around the contour:
When G451 is activated and with acute contour angles, superfluous non-cutting tool paths
can result from lift-off movements. A parameter can be used in the machine data to define
automatic switchover to transition circle in such cases.
Fundamentals
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
10.3 Compensation at the outside corners (G450, G451, DISC)
Tool radius compensation
297