Machining open contour corners with M98

Application

If the tool performs a machining operation on a radius-compensated contour, then residual material remains at the inside corners. With M98 the control extends the tool path by the tool radius so that the tool completely machines an open contour and removes all residual material.

Description of function

Effect

M98 is in effect blockwise and takes effect at the end of the block.

Application example

Open contour without M98

Open contour with M98

11 L X+0 Y+50 RL F1000

12 L X+30

13 L Y+0 M98

; Completely machine an open contour corner

14 L X+100

; The control maintains the position of the Y axis with M98

15 L Y+50

The control moves the tool along the contour with radius compensation. With M98 the control calculates the contour ahead of time and determines a new path intersection in the extension of tool path. The control moves the tool beyond this path intersection and completely machines the open contour.

In the next NC block the control maintains the position of the Y axis.

Without M98 the control uses the programmed coordinates as limitation for the radius-compensated contour. The control calculates the path intersection so that the contour is not damaged and residual material remains.