HEIDENHAIN TNC 640 (34059x-04) Cycle programming - Manual (Page 128)

Fixed Cycles: Tapping / Thread Milling
4.9 HELICAL THREAD DRILLING/MILLING (Cycle 265, DIN/ISO: G265)
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TNC 640 | User's Manual Cycle Programming | 3/2014
Please note while programming:
Program a positioning block for the starting point
(hole center) in the working plane with radius
compensation
R0.
The algebraic sign of the cycle parameters depth
of thread or sinking depth at front determines the
working direction. The working direction is defined in
the following sequence:
1. Thread depth
2. Depth at front
If you program a depth parameter to be 0, the TNC
does not execute that step.
If you change the thread depth, the TNC
automatically changes the starting point for the
helical movement.
The type of milling (up-cut/climb) is determined by
the thread (right-hand/left-hand) and the direction of
tool rotation, since it is only possible to work in the
direction of the tool.
Danger of collision!
Use the machine parameter
displayDepthErr to
define whether, if a positive depth is entered, the
TNC should output an error message (on) or not (off).
Keep in mind that the TNC reverses the calculation
for pre-positioning when a
positive depth is
entered . This means that the tool moves at rapid
traverse in the tool axis to set-up clearance below
the workpiece surface!