Programming technology functions (cycles)
8.4 Milling
Turning
426 Operating Manual, 03/2013, 6FC5398-8CP40-3BA1
8.4.11 Thread milling (CYCLE70)
Function
Using a thread cutter, internal or external threads can be machined with the same pitch.
Threads can be machined as right-hand or left-hand threads and from top to bottom or vice
versa.
For metric threads (thread pitch P in mm/rev), the cycle assigns a value (calculated on the
basis of the thread pitch) to the thread depth H1 parameter. You can change this value. The
default selection must be activated via a machine data code.
Machine manufacturer
Please refer to the machine manufacturer's specifications.
The entered feedrate acts on the workpiece contour, i.e. it refers to the thread diameter.
However the feedrate of the cutter center point is displayed. That is why a smaller value is
displayed for internal threads and a larger value is displayed for external threads than was
entered.
Approach/retraction when milling internal threads
1. Positioning on retraction plane with rapid traverse.
2. Approach of starting point of the approach circle in the current plane with rapid traverse.
3. Infeed to a starting point in the tool axis calculated internally in the controller with rapid
traverse.
4. Approach motion to thread diameter on an approach circle calculated internally in the
controller with the programmed feedrate, taking into account the finishing allowance and
maximum plane infeed.
5. Thread cutting along a spiral path in clockwise or counter-clockwise direction (depending
on whether it is left-hand/right-hand thread, for number of cutting teeth of a milling plate
(NT) ≥ 2 only one rotation, offset in the Z direction).
To reach the programmed thread length, traversing is beyond the Z1 value for different
distances depending on the thread parameters.
6. Exit motion along a circular path in the same rotational direction at programmed feedrate.
7. With a programmed number of threads per cutting edge NT > 2, the tool is fed in (offset)
by the amount NT-1 in the Z direction. Points 4 to 7 are repeated until the programmed
thread depth is reached.
8. If the plane infeed is less than the thread depth, points 3 to 7 are repeated until the thread
depth + programmed allowance is reached.
9. Retract on the thread center point and then to retraction plane in the tool axis in rapid
traverse.
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