HEIDENHAIN TNC 620 (340 56x-02) ISO programming - Manual (Page 157)

HEIDENHAIN TNC 620 157
6.3 Cont
our Appr
oac
h
and Depar
tur
e
Tangential approach and departure
With G26 (figure at center right), you can program a tangential approach
to the workpiece, and with G27 (figure at lower right) a tangential
departure. In this way you can avoid dwell marks.
Starting point and end point
The starting point and the end point lie outside the workpiece, close
to the first and last contour points. They are to be programmed
without radius compensation.
Approach
U G26 is entered after the block in which the first contour element is
programmed: This will be the first block with radius compensation
G41/G42
Departure
U G27 after the block in which the last contour element is
programmed: This will be the last block with radius compensation
G41/G42
X
Y
A
R
S
G41
G40
X
Y
G41
G40
E
R
B
The radius for G26 and G27 must be selected so that the
TNC can execute the circular path between the starting
point and the first contour point, as well as the last contour
point and the end point.