Originally Posted by
gwood
Witbike, In the electrical cabinet listed on you prints is a 3-Phase Contactor labeled "M11". This is energized when the door is closed and de-energized with the door open.
It is inline with the Spindle drive output to the motor. If the door is opened at the end of cycle when the spindle is decelerating it will cause the contacts to ARC and burn.
This will cause the symptoms you speak of at slow RPMs and when in Contouring mode for M19 and Tool changes. With power off and locked out;
I would take the "M11" contactor apart and examine the contacts.