Siemens SINUMERIK 840Di sl Programming Manual page 275

Note
If the path lengths vary greatly from block to block, a new F value should be specified in
each block with G93. The feedrate can also be specified in deg/rev when machining with
rotary axes.
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
Fundamentals
Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
Feedrate Control and Spindle Motion
7.1 Feedrate (G93, G94, G95 or F..., FGROUP, FGREF)
275