Owner's manual

Programming Feedrates
Chapter 18
18-4
To avoid this problem, the system installer must set a minimum feed
reduction percentage (MFR) in AMP. This will set a minimum feedrate to
be used whenever the value of Rc/Rp is very small. If Rc/Rp control will
reduce the tool radius center feedrate no more than the MFR percentage.
In G93 (inverse time feed) mode, the F--word represents the amount of
programmed axis or axes motion that will be completed in a minute
(moves per minute). For example, if a G93 block were programmed with a
move to X20 (from X0) and a feedrate of 0.2, the X axis would move 0.2
of the m ove (to X4) in one minute.
Another way of describing this would be to refer to the F--word as the
inverse
of the a mount of time to complete a programmed move. If it were
desired to complete t he move described above in 2 minutes, then the
F--word value would be 1/2 (program 0.5).
If the programmed move is a circular move (G02 or G03 modes), then the
F--word represents the number of radians of the arc or circle to be moved
per minute (radians per minute).
In G93 mode, an F--word is effective only in the block it is programmed (F
is not modal in G93). Therefore, a ll blocks that call for axis motion when
G93 is active, must
contain a n F--word or an error occurs.
G93 is modal. It remains active until cancelled by a G94 (feed per minute)
or G95 (feed per revolution).
Figure 18.3
Inverse Time Feed (G93)
Programmed
move
Table
Distance moved in 1minute
iffeedrate (F ) value was
0.5 (move perminute)
Cutting
tool
Workpiece
18.1.2
Inverse Time Feed Mode
(G93)