July 2013 8.1 Display and operation 1223
Tasks of AFC in each machining section:
Detection of entry into the material by the cutter when the idle load is
exceeded by 2%. Regulate to entry speed until a path corresponding to the
cutter radius has been cleared, but at most 600 ms.
Calculation of the optimum feed-rate factor.
Monitoring for overload and switch-off reaction.
Saving the maximum value of the spindle power for the evaluation.
Detection of exit from the material by the cutter when the power is below
the programmed exit load, and regulation to the exit speed until a path
corresponding to the cutter radius has been traversed.
After detection of traverse in air, regulate to the programmed idle feed rate.
AFC is not in effect when machining at rapid traverse, since FMAX is used
in the IPO, and at times override for FMAX.
As an alternative method for controlling with AFC, you can use the value in
PLC word W632 [value in tenths of percent] as control input variable, instead
of using the spindle power in percent. A spindle power of 50% corresponds
to the value 500 to be entered in W632 (0.1% corresponds to the value 1). This
may be necessary for individual applications (e. g. pecking).
The control input variable in W632 must be calculated in the PLC program,
which can best be done with a fast PLC cycle (e.g. 15 ms). Also, when word
W632 is used, no idle load for the spindle is determined and no transitional
period for the tool entering or leaving the workpiece is considered.
This function must be activated by entering AFC.PLCCONTROL = ON in the
OEM.SYS.
However, the function only works if a value is entered in W632.
Automatic
selection of the
Learning /
Controlling status
If an NC program is selected for machining and started, and if AFC is active,
then it is first checked whether an associated <name>.AFC.DEP file exists in the
same directory as the NC file. If this is the case, then the data in this file are
immediately used as control parameters, and machining is performed with
adaptive feed control. If this file does not exist, the first machining run is used
as the learning phase and the file is created. If the AFC file is determined to be
incomplete during machining, the missing steps are automatically performed
in the Learning mode, thereby generating the missing data.
When Learning is deactivated (M05, manually via soft key, or with FN 17), the
learned data are saved and the status of this data block is set to "Controlling."
During Controlling, the data blocks are read in the same sequence they were
learned, the step numbers are evaluated and other parameters (tool number,
index) are checked to see if they match.
The current status or mode of AFC is stored in PLC Word W348 (inactive = 0,
learning phase = 1, controlling = 2).
W348 = 0: AFC inactive (OFF)
W348 = 1: AFC in learning phase
W348 = 2: AFC is controlling
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