HEIDENHAIN TNC 620 Programming Station, User Manual

Page: 243 / 695

Approaching and departing a contour 6.3
6
HEIDENHAIN | TNC 620 | ISO Programming User's Manual | 9/2016
243
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
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
G27
after the block in which the last contour element
is programmed: This will be the last block with radius
compensation
G41/G42
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.