5. FEED FUNCTIONS
Feed amount per minute
(mm/min or inch/min)
Fig. 5.3 (b) Feed per minute
No override can be used for some commands such as for
After specifying G99 (in the feed per revolution mode), the amount of
feed of the tool per spindle revolution is to be directly specified by setting
a number after F. G99 is a modal code. Once a G99 is specified, it is valid
until G98 (feed per minute) is specified.
An override from 0% to 254% (in 1% steps) can be applied to feed per
revolution with the switch on the machine operator’s panel. For detailed
information, see the appropriate manual of the machine tool builder.
If bit 0 (NPC) of parameter No. 1402 has been set to 1, feed–per–rotation
commands can be specified even when a position coder is not being used.
(The CNC converts feed–per–rotation commands to feed–per–minute
Feed amount per spindle revolution
(mm/rev or inch/rev)
Fig. 5.3 (c) Feed per revolution
When the speed of the spindle is low, feedrate fluctuation
may occur. The slower the spindle rotates, the more
frequently feedrate fluctuation occurs.
A common upper limit can be set on the cutting feedrate along each axis
with parameter No. 1422. If an actual cutting feedrate (with an override
applied) exceeds a specified upper limit, it is clamped to the upper limit.
D Feed per revolution
D Cutting feedrate clamp