Siemens SINUMERIK 840DE Programming Manual page 182

Programming Motion Commands
4.22 Chamfer, rounding (CHF, CHR, RND, RNDM, FRC, FRCM)
Description
Note
Chamfer/rounding
If the programmed values for chamfer (CHF/CHR) or rounding (RND/RNDM) are too large
for the associated contour elements, then the chamfer or rounding are automatically reduced
to a suitable value.
No chamfer/rounding is inserted, if
No straight or circle contour is available in the plane,
A movement is taking place outside the plane,
A plane change is taking place, or
The number of blocks - which is specified in the machine data - not containing information
for traversing (e.g., only command output), is exceeded.
Note
FRC/FRCM
FRC/FRCM has no effect if a chamfer is being machined with G0; the command can be
programmed according to the F value without error message.
The reference to the blocks, in which chamfer and rounding are programmed and to the
technology is set in machine data.
FRC is operative only if a chamfer/rounding is programmed in the same block or if RNDM
has been activated.
FRC overwrites the F or FRCM value in the current block.
The feedrate programmed under FRC must be greater than zero.
FRCM=0 activates the feed programmed in F for the chamfer/rounding.
If FRCM is programmed, the FRCM value must be reprogrammed, analogous to F, on
changeover G94<->95, etc. If only a new F value is programmed, and if FRCM > 0 before
the feed type changes, error message 10860 (no feed programmed) will be activated.
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Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals