Siemens SINUMERIK 808D ADVANCED Programming And Operating Manual page 170

Sequence
Position reached prior to cycle start:
Starting position is any position from which the contour starting point can be approached at the height of the retraction plane
without collision.
The cycle generates the following sequence of motions when roughing:
The depth infeeds are distributed equally with the maximum possible value of the specified parameters.
● Traversing to the starting point for first milling with G0/G1 (and FF3). This point is calculated internally in the control
system and depends on the following factors:
– Contour starting point (first point in the subroutine),
– Direction of the contour at the starting point,
– Approach mode and its parameters
– Tool radius
The cutter radius compensation is activated in this block.
● Depth infeed to the first or next machining depth plus programmed safety clearance with G0/G1. The first machining
depth results from the following data:
– Total depth
– Finishing allowance
– The maximum possible depth infeed
● Approach of the contour vertically with depth infeed _FFD and then in the plane at the programmed feedrate _FFP1 or
3D with the feedrate programmed under _FAD according to the programming for smooth approach
● Milling along the contour with G40/G41/G42
● Smooth retraction from the contour with G1 while continuing feed for the surface machining by the retraction amount
● Retraction with G0/G1 (and feedrate for intermediate paths _FF3), depending on the programming
● Retraction to the depth infeed point with G0/G1 (and _FF3).
● This sequence is repeated on the next machining plane up to finishing allowance in the depth.
Upon completion of roughing, the tool stands above the point (calculated internally in the control system) of retraction from
the contour at the height of the retraction plane.
The cycle generates the following sequence of motions when finishing:
During finishing, milling is performed at the relevant infeed along the base of the contour until the final dimension is reached.
Smooth approach and retraction of the contour is carried out according to the existing parameters. The appropriate path is
calculated internally in the control system.
At the end of the cycle, the tool is positioned at the contour retraction point at the height of the retraction level.
Note
Contour programming
When programming the contour, observe the following:
● No programmable offset may be selected in the subroutine prior to the first programmed position.
● The first block of the contour subroutine is a straight line block containing G90/G0 or G90/G1 and defines the start of the
contour.
● The starting condition of the contour is the first position in the machining plane which is programmed in the contour
subroutine.
● The cutter radius compensation is selected/deselected by the higher-level cycle; therefore, no G40, G41, G42 is
programmed in the contour subroutine.
170
Programming and Operating Manual (Milling)
6FC5398-4DP10-0BA1, 01/2014