Siemens SINUMERIK 840D sl Turning Operating Manual page 297

Note for selecting the clamp spindle function under ShopTurn
The machine manufacturer also specifies whether ShopTurn will clamp the spindle
automatically if this would facilitate machining, or if you can decide the types of machining for
which the spindle should be clamped.
If you are to decide the types of machining for which the spindle is to be clamped, the following
applies:
You should note that when machining in the end face/end face C and peripheral surface/
peripheral surface C planes, clamping only remains active for contour milling and drilling
operations. On the other hand, when machining in the end face Y/end face B and peripheral
surface Y planes, clamping is modal, i.e. it remains active until the machining plane is changed.
Turning
Operating Manual, 06/2019, A5E44903486B AB
Creating a ShopTurn program
9.4 Fundamentals
297