Fundamentals

Application

Adaptive Feed Control (AFC) saves time when processing NC programs and reduces wear on the machine. The control regulates the contouring feed rate during program run depending on the spindle power. In addition, the control responds to overloading of the spindle.

Requirements

  • Adaptive Feed Control (AFC, software option 45)
  • Enabled by the machine manufacturer
  • The machine manufacturer uses the optional machine parameter Enable (no. 120001) to define whether you can use AFC.

Description of function

If AFC is active in the teach-in cut or in control mode, the control displays an icon in the Positions workspace.

Positions workspace

Detailed information about the function is provided by the control on the AFC tab of the Status workspace.

AFC tab (option 45)

Benefits of AFC

  • Adaptive feed control (AFC) has the following advantages:
  • Optimization of machining time
  • By controlling the feed rate, the control tries to maintain the previously recorded maximum spindle power or the reference power specified in the tool table (AFC-LOAD column) during the entire machining time. It shortens the machining time by increasing the feed rate in machining zones with little material removal.

  • Tool monitoring
  • If the spindle power exceeds the taught-in or specified maximum value, the control reduces the feed until the reference spindle power is reached. If the minimum feed rate is exceeded, the control executes a shutdown response. AFC can also use the spindle power to monitor the tool for wear and breakage without changing the feed rate.

    Monitoring tool wear and tool load

  • Protection of the machine’s mechanical elements
  • Timely feed rate reduction and shutdown responses help to avoid machine overload.

Tables related to AFC

  • The control offers the following tables in conjunction with AFC:
  • AFC.tab
  • In the AFC.TAB table, you can enter the feed rate control settings to be used by the control. This table must be saved in the TNC:\table directory.

    Basic AFC settings in AFC.tab

  • *.H.AFC.DEP
  • With a teach-in cut, the control at first copies the basic settings for each machining step, as defined in the AFC.TAB table, to a file called <name>.H.AFC.DEP. The string <name> is identical to the name of the NC program for which you have recorded the teach-in cut. In addition, the control measures the maximum spindle power consumed during the teach-in cut and saves this value to the table.

    AFC.DEP settings file for teach-in cuts

  • *.H.AFC2.DEP
  • During a teach-in cut, the control stores information for each machining step in the <name>.H.AFC2.DEP file. The string <name> is identical to the name of the NC program for which you are perfoming the teach-in cut.

    In control mode, the control updates the data in this table and performs evaluations.

    Log file AFC2.DEP

You can open and, if necessary, edit the tables for AFC during program run. The control offers only the tables for the active NC program.

Editing tables for AFC

Notes

 
Notice
Caution: Danger to the tool and workpiece!
As soon as Adaptive Feed Control (AFC) is deactivated, the control immediately switches back to the programmed machining feed rate. If AFC decreased the feed rate (e.g., due to wear) before it was deactivated, the control accelerates the feed rate up to the programmed value. This behavior applies regardless of how the function is deactivated. This feed acceleration may result in damage to the tool and/or the workpiece!
  1. If the feed rate falling below the FMIN value is imminent, stop the machining operation without deactivating AFC
  2. Define the overload response for cases in which the feed rate falls below the FMIN value
  • If adaptive feed control is active in Control mode, the control executes a shutdown response independent of the programmed overload response.
    • If, with the reference spindle load, the value falls below the minimum feed factor
    • The control executes the shutdown response from the OVLD column of the AFC.tab table.

      Basic AFC settings in AFC.tab

    • If the programmed feed rate falls below the 30% threshold
    • The control executes an NC stop.

  • Adaptive feed control is not intended for tools with diameters less than 5 mm. If the rated power consumption of the spindle is very high, the limit diameter of the tool may be larger.
  • Do not work with adaptive feed control in operations in which the feed rate and spindle speed must be adapted to each other, such as tapping.
  • In NC blocks containing FMAX, the adaptive feed control is not active.
  • With the machine parameter dependentFiles (no. 122101), the machine manufacturer defines whether the control displays dependency files in the file management.