HEIDENHAIN TNC 320 User Manual page 108

4.7 THREAD
MILLING/COUNTERSINKING
(Cycle 263, DIN/ISO: G263)
Cycle run
1 The TNC positions the tool in the tool axis at rapid traverse FMAX
to the programmed set-up clearance above the workpiece surface.
Countersinking
2 The tool moves at the feed rate for pre-positioning to the
countersinking depth minus the set-up clearance, and then at the
feed rate for countersinking to the countersinking depth.
3 If a set-up clearance to the side has been entered, the TNC
immediately positions the tool at the feed rate for pre-positioning
to the countersinking depth.
4 Then, depending on the available space, the TNC makes a
tangential approach to the core diameter, either tangentially from
the center or with a pre-positioning move to the side, and follows
a circular path.
Countersinking at front
5 The tool moves at the feed rate for pre-positioning to the
countersinking depth at front.
6 The TNC positions the tool without compensation from the center
on a semicircle to the offset at front, and then follows a circular
path at the feed rate for countersinking.
7 The TNC then moves in a semicircle to the hole center.
Thread milling
8 The TNC moves the tool at the programmed feed rate for pre-
positioning to the starting plane for the thread. The starting plane
is determined from the thread pitch and the type of milling (climb
or up-cut).
9 Then the tool moves tangentially on a helical path to the thread
diameter and mills the thread with a 360° helical motion.
10 After this, the tool departs the contour tangentially and returns to
the starting point in the working plane.
11 At the end of the cycle, the TNC retracts the tool at rapid traverse
to the set-up clearance, or—if programmed—to the 2nd set-up
clearance.
108 Fixed Cycles: Tapping / Thread Milling