Siemens SINUMERIK 808D ADVANCED Programming And Operating Manual page 207

Function
By using the cycle CYCLE90, you can produce internal or external threads. The path when milling threads is based on a
helix interpolation. All three geometry axes of the current plane, which you define before calling the cycle, are involved in this
motion.
Sequence for external thread
Position reached prior to cycle start:
The starting position is any position from which the starting position at the outside diameter of the thread at the height of the
retraction plane can be reached without collision.
This start position for thread milling with G2 lies between the positive abscissa and the positive ordinate in the current level
(i.e. in the first quadrant of the coordinate system). For thread milling with G3, the start position lies between the positive
abscissa and the negative ordinate (namely in the fourth quadrant of the coordinate system).
The distance from the thread diameter depends on the size of the thread and the tool radius used.
The cycle creates the following sequence of motions:
● Positioning on the starting point using G0 at the height of the retraction plane in the applicate of the current plane
● Infeed to the reference plane brought forward by the safety clearance for swarf removal, using G0
● Approach motion to the thread diameter along a circle path opposite to the direction G2/G3 programmed under CDIR
● Thread milling along a helix path using G2/G3 and the feedrate value FFR
Programming and Operating Manual (Milling)
207
6FC5398-4DP10-0BA1, 01/2014