Feedrate Optimization For Curved Path Sections (Cftcp, Cfc, Cfin) - Siemens SINUMERIK 828D Programming Manual

Feed control

7.9 Feedrate optimization for curved path sections (CFTCP, CFC, CFIN)

7.9 Feedrate optimization for curved path sections (CFTCP, CFC, CFIN)
Function
With activated offset mode G41/G42, the programmed feedrate for the milling cutter radius
initially refers to the milling cutter center path (see the chapter titled "Coordinate
transformations (frames)").
When you mill a circle (the same applies to polynomial and spline interpolation) the extent to
which the feedrate varies at the cutter edge is so significant under certain circumstances that
it can impair the quality of the machined part.
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
Significance
CFTCP
CFC
CFIN
146
: 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, 07/2010, 6FC5398-1BP40-0BA0
Fundamentals