Siemens Sinumerik 840D sl Programming Manual page 124

Feed control
8.9 Feedrate optimization for curved path sections (CFTCP, CFC, CFIN)
Example: Milling a small outside radius with a large tool. The path that the outside of the milling
tool must travel is considerably longer than the path along the contour.
Because of this, machining at the contour takes place with a very low feedrate. To prevent
adverse effects, the feedrate needs to be controlled accordingly for curved contours.
Syntax
CFTCP
CFC
CFIN
Meaning
CFTCP:
CFC:
CFIN:
124
Constant feedrate on the milling cutter center path
The control keeps the feedrate constant and feedrate offsets are deactivated.
Constant feedrate at the contour (tool cutting edge).
This function is preset per default.
Constant feedrate at the tool cutting edge only at concave contours, otherwise on the
milling cutter center path.
The feedrate is reduced for inside radii.
Programming Manual, 01/2015, 6FC5398-1BP40-5BA2
Fundamentals