Siemens SINUMERIK 840DE Programming Manual page 257

Unit of measurement for synchronized axes with limit speed FL
The unit of measurement set for F by G command (G70/G71) also applies to FL. If FL is not
programmed, rapid traverse velocity is used. FL is deselected by assignment to MD
$MA_AX_VELO_LIMIT.
Unit of measurement for rotary and linear axes
For linear and rotary axes, which are combined with FGROUP and traverse a path together,
the feed is interpreted in the unit of measurement of the linear axes. Depending on the
default for G94/G95: mm/min or inch/min and mm/rev or inch/rev.
The tangential velocity of the rotary axis in mm/min or inch/min is calculated according to the
following formula:
F[mm/min] = F'[degrees/min] * π * D[mm]/360[degrees]
F: Tangential velocity
F': Angular velocity
π: Circle constant
D: Diameter
Traverse rotary axes with path velocity F, FGREF
For machining operations, in which the tool or the workpiece or both are moved by a rotary
axis, the effective machining feedrate is to be interpreted as a path feed in the usual way by
reference to the F value. This requires the specification of an effective radius (reference
radius) FGREF for each of the rotary axes involved.
The unit of the reference radius depends on the G70/G71/G700/G710 setting.
All axes involved must be included in the FGROUP command, as before, in order to be
evaluated in the calculation of the path feed.
Fundamentals
Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Feedrate Control and Spindle Motion
7.1 Feedrate (G93, G94, G95 or F..., FGROUP, FGREF)
F
F'
7-7