HEIDENHAIN TNC 640 (34059x-04) - Manual (Page 220)

Programming: Programming contours
6.4 Path contours - Cartesian coordinates
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TNC 640 | User's Manual
HEIDENHAIN Conversational Programming | 3/2014
Circle CT with tangential connection
The tool moves on an arc that starts tangentially to the previously
programmed contour element.
A transition between two contour elements is called tangential
when there is no kink or corner at the intersection between the
two contours—the transition is smooth.
The contour element to which the tangential arc connects must
be programmed immediately before the
CT block. This requires at
least two positioning blocks.
Coordinates of the arc end point, and if
necessary:
Feed rate F
Miscellaneous function M
Example NC blocks
7 L X+0 Y+25 RL F300 M3
8 L X+25 Y+30
9 CT X+45 Y+20
10 L Y+0
A tangential arc is a two-dimensional operation:
the coordinates in the
CT block and in the contour
element preceding it must be in the same plane of
the arc!