HEIDENHAIN TNC 360 ISO Programming - Manual (Page 168)

8-15
8 Cycles
TNC 360
8.3 SL Cycles
Subcontour list (SL) cycles are very powerful cycles that enable you to mill
any required contour. They are characterized by the following features:
• A contour can consist of superimposed subcontours. Pockets and
islands compose the subcontours.
• The subcontours are programmed as subprograms.
• The control automatically superimposes the subcontours and calculates
the points of intersection of the subcontours with each other.
Cycle G37: CONTOUR GEOMETRY contains the subcontour list and is a
purely geometric cycle, containing no cutting data or infeed values.
The machining data are defined in the following cycles:
• PILOT DRILLING G56
• ROUGH-OUT G57
• CONTOUR MILLING G58/G59
Each subprogram defines whether radius compensation G41 or G42
applies. The sequence of points determines the direction of rotation in
which the contour is to be machined. The control deduces from these
data whether the specific subprogram describes a pocket or an island:
• For a pocket the tool path is inside the contour
• For an island the tool path is outside the contour
• The way the SL contour is machined is determined by MP 7420.
• We recommend a graphical test run before you machine the part. This will show whether all contours were
correctly defined.
• All coordinate transformations are allowed in the subprograms for the subcontours.
• F and M words are ignored in the subprograms for the subcontours.
The following examples will at first use only the ROUGH-OUT cycle.
Later, as the examples become more complex, the full range of possibili-
ties of this group of cycles will be illustrated.
Programming parallel axes
Machining operations can also be programmed in parallel axes as SL
cycles. The parallel axes must lie in the working plane. (In this case,
graphic simulation is not available).
Input
Parallel axes must be programmed in the first coordinate block (position-
ing block, I,J,K block) of the first subprogram that is called with cycle G37:
CONTOUR GEOMETRY. All other coordinates are then ignored.