Contour Programming - Siemens SINUMERIK 840D Programming Manual

3
Milling Cycles
3.15 Pocket milling with islands – CYCLE73, CYCLE74, CYCLE75

3.15.3 Contour programming

Pocket edge and island contours must always be closed, i.e. the
start and end points are identical.
The start point, i.e. first point on a contour must always be
programmed with G0, and all other contour elements via G1 to
G3.
When the contour is programmed, the last contour element
(block with label or block number at end of contour) must not
contain a radius or chamfer.
The tool may not stand at a starting position of the programmed
contour element before CYCLE73 is invoked.
The necessary programs must always be stored in one directory
(workpiece or parts program). It is permissible to use the
subroutine memory for pocket edge or island contours.
Workpiece-related geometric dimensional data may be
programmed in either metric or inches. Switching between these
units of measurement within individual contour programs will
causes errors in the machining program.
When G90/G91 are programmed alternately in contour
programs, care must be taken to program the correct
dimensional command at the start of the program in the
sequence of contour programs to be executed.
When the pocket machining program is calculated, only the
geometries in the plane are taken into account.
If other axes or functions (T.., D.., S.. M.. etc.) are programmed in
contour sections, they are skipped when the contour is prepared
internally in the cycle.
All machine-specific program commands (e.g. tool call, speed, M
command) must be programmed before the cycle commences.
Feedrates must be set as parameters in CYCLE73.
The tool radius must be greater than zero.
It is not possible to repeat island contours by offsets implemented
by suitable control commands (e.g. zero offset, frames, etc.).
Every island to be repeated must always be programmed again
with the offsets calculated into the coordinates.
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SINUMERIK 840D/840Di/810D Programming Guide Cycles (PGZ) – 11.02 Edition
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