Siemens SINUMERIK 840DE Programming Manual page 258

Feedrate Control and Spindle Motion
7.1 Feedrate (G93, G94, G95 or F..., FGROUP, FGREF)
In order to ensure compatibility with the behavior with no FGREF programming, the factor 1
degree = 1mm is activated on system powerup and RESET. This corresponds to a reference
radius of FGREF=360 mm/(2π)=57.296 mm.
Note
This default setting is independent of the active basic system MD 10240:
SCALING_SYSTEM_IS_METRIC and of the currently active inch/metric G code.
Special situations: With the following programming:
N100 FGROUP(X,Y,Z,A)
N110 G1 G91 A10 F100
N120 G1 G91 A10 X0.0001 F100
the F value programmed in N110 is evaluated as a rotary axis feedrate in deg/min, while the
feedrate weighting in N120 is either 100 inch/min or 100 mm/min depending on the currently
active inch/metric setting.
Path reference factors for orientation axes with FGREF
With orientation axes the mode of operation of the FGREF[ ] factors is dependent on
whether the change in the orientation of the tool is implemented by rotary axis or vector
interpolation.
In the case of rotary axis interpolation, the relevant FGREF factors of the orientation axes
are calculated, as for rotary axes, individually as reference radius for the axis paths.
In the case of vector interpolation, an effective FGREF factor, which is calculated as the
geometric mean value of the individual FGREF factors, is applied.
FGREF[eff] = n-te root of:[(FGREF[A] * FGREF[B]...)]
They are:
A: Axis identifier of 1st orientation axis
B: Axis identifier of 2nd orientation axis
C: Axis identifier of 3rd orientation axis Number of orientation axes
Example: There are two orientation axes for a standard 5-axis transformation, and the
effective factor is thus the root of the product of the two axial factors:
FGREF[eff] = square root of:[(FGREF[A] * FGREF[B])]
Note
With the effective factor for orientation axes FGREF, it is therefore possible to define a
reference point on the tool, to which the programmed path feedrate refers.
7-8
Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals