HEIDENHAIN TNC 320 User Manual page 116

4.9 HELICAL THREAD
DRILLING/MILLING (Cycle 265,
DIN/ISO: G265)
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 at front
2 If countersinking is before thread milling, the tool moves at the
feed rate for countersinking to the sinking depth at front. If
countersinking occurs after thread milling, the TNC moves the tool
to the countersinking depth at the feed rate for pre-positioning.
3 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.
4 The tool then moves in a semicircle to the hole center.
Thread milling
5 The TNC moves the tool at the programmed feed rate for pre-
positioning to the starting plane for the thread.
6 The tool then approaches the thread diameter tangentially in a
helical movement.
7 The tool moves on a continuous helical downward path until it
reaches the thread depth.
8 After this, the tool departs the contour tangentially and returns to
the starting point in the working plane.
9 At the end of the cycle, the TNC retracts the tool at rapid traverse
to set-up clearance, or—if programmed—to the 2nd set-up
clearance.
116 Fixed Cycles: Tapping / Thread Milling