Adaptive Feed Control (Afc) - HEIDENHAIN iTNC 530 HSCI Technical Manual

8.1.11 Adaptive feed control (AFC)

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With adaptive feed control (AFC, software option 45), the contouring feed rate
is regulated depending on the respective spindle power in percent. This is
done with the help of the feed-rate override factor, which is normally
determined in the PLC by the setting of the override potentiometer. If AFC is
active, then this factor is no longer formed from the potentiometer, but rather
from the spindle power and other process data, and the contouring feed rate
is calculated. The iTNC then automatically changes the value of the feed-rate
override factor, with the goal of maintaining the spindle power at a constant
reference value.
The main benefit of this process control, along with ensuring the quality of the
machining procedure (e.g. detection of cutter breakage or wear), is the
optimization of the machining time, which is intended to ensure or improve
productivity and efficiency. Changes in the material (harder sections),
deviations in oversizes and tool wear lead to the danger of overloading the
spindle. AFC can be effective in counteracting this.
Benefits of adaptive feed control:
Optimizing the machining time:

By regulating the feed rate, the attempt is made to maintain the maximum
spindle power learned over the entire machining time.
The total machining time is reduced by increasing the feed rate in machining
zones where less material is being removed.
Tool monitoring:

The tool life of a tool is increased by reducing the feed rate when the
maximum spindle power learned is exceeded, until the time when this
reference spindle power is reached again.
If it is detected that the maximum spindle power was exceeded and at the
same time the minimum feed rate could not be maintained, a programmed
switch-off reaction is performed. This avoids subsequent damage due to
cutter breakage or wear.
The machine's mechanical elements are protected

Damage to the machine due to overload can be avoided by reducing the
feed rate ahead of time and with appropriate switch-off reactions.
Documentation by capturing and saving the learning and process data.

Limitations regarding the use of AFC:
AFC cannot be used with analog spindles.

AFC cannot be used in volts-per-hertz control mode.

HEIDENHAIN Technical Manual iTNC 530 HSCI