Wear compensation of tool radius

Grinding a contour

Use tool radius wear compensation (radius compensation) by preference to grind a contour at the same time as tool radius compensation.

Grinding disc wear in the direction of the disc radius can be compensated continuously or discretely.

In the radius compensation processing type, wear is only considered for active tool radius compensation (TRC).

The figure below shows the tool radius wear:

Wear compensation of tool radius
Wear compensation of tool radius



The start-up movement in relation to the equidistant path after selecting TRC (G41/G42) is considered without wear.

Motion after deselecting TRC (G40) is also without wear.

Programing Example


General #OTC programming example

N10 F10000

N20 D1                  (Data set selection for grinding wheel)

N30 G0 X0 Y0 Z0

N40 #OTC[RADIUS, AUTO] (define OTC processing type + mode)

N50 #OTC ON             (select OTC)

N60 G41 G01 X50         (select TRC, wear-free movement)

N70 X1000

N80 G40 X50             (deselect TRC with path motion to reduce TRC)

N90 #OTC OFF            (deselect OTC)

N100 G00 X50

N199 M30

Programing Example


OTC with discrete compensation


N20 G17G90

N22 D1 G25              (Linear transition block)

N40 G1 X0Y0Z0 F600


N55 G42

N60 G1 X2

N70 G1 X102

N80 G26 Y100            (Circular transition block)

N90 X2

N95 Y0

N100 G40 G1 X0


N99999 M30



Path contour with active TRC without OTC offset


Path contour with negative value for OTC radius offset


Path contour with positive value for OTC radius offset

Contour of the NC program wr_quad_disc.nc
Contour of the NC program wr_quad_disc.nc

Explanation to the figure above (the discrete OTC offset applied is 2 mm)

  1. In this corner of the contour, G25 is active. The contour is not continuous. The predefined OTC offset is applied to another axis over several cycles.
  2. The TRC inserts a circular transition because of G26. But the OTC offset is so large that the increase in offset is unable to keep up with the continuous change in the contour.
  3. The OTC offset lags behind considerably.
  4. Increase the OTC offset
  5. Decrease the positive OTC offset and increase the negative OTC offset

The tool radius is influenced by the PLC.

Condition: After the OTCRadiusOffset control unit is active, the OTC radius offset can then be programmed accordingly for the build currently in use. This value is then added to each cycle perpendicular to the programmed contour.

PLC example code

(* Enable the OTC control unit for first channel *)

gpCh[0]^.bahn_mc_control.otc_radius_offset.enable_w := TRUE;

(* write radius offset in the first channel *)

gpCh[0]^.bahn_mc_control.otc_radius_offset.command_w := OTC_Offset;



A continuous contour path is recommended because changing the orientation of the predefined offset is not applied to the axis all at once but is distributed over several cycles.



On selection, the commands G41/G42 and #OTC ON can be swapped. On deselection, the sequence G40 before #OTC OFF must be maintained. The TRC modes G138/G139 make a path motion between the two commands absolutely necessary.
If error 90050 is output, the path motion does not exist when deselected with G138/G139.

The functionality of the RADIUS type is shown by the example of the G17 plane:

Description of RADIUS function
Description of RADIUS function