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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 75071 - MCSC: collision monitoring axis
Alarm 75071 indicates the collision monitoring function in the SINUMERIK 840D has detected an unexpected force or load condition on the specified axis, triggering the safety-critical overload detection mechanism. This alarm is generated by the NCK servo loop when actual axis current or load feedback exceeds the collision threshold parameters during programmed motion.
75071
Siemens 75071 - MCSC: collision monitoring axis
MCSC: collision monitoring axis
The collision monitor has responded because the deceleration precomputation has detected that the distance between the axes has fallen below the configured distance Control reaction: Alarm display. NC Stop on alarm.
Root Cause Summary
Alarm 75071 indicates the collision monitoring function in the SINUMERIK 840D has detected an unexpected force or load condition on the specified axis, triggering the safety-critical overload detection mechanism. This alarm is generated by the NCK servo loop when actual axis current or load feedback exceeds the collision threshold parameters during programmed motion.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Access Diagnostics menu on 840D operator panel: Navigate to [Diagnosis] → [Servo] → [Axis Monitor] to view real-time load current on axis %2 during manual jogging at reduced feed rate (F100-F200).
Do not jog toward workpiece until baseline current is established.
- 2
Review MD32020 (COLLISION_MONITOR_THRESHOLD_PERCENT) via NCK Parameters menu. Typical values range 80-150% of rated axis current. Verify the threshold is set ≥120% for milling applications; increase to 140-160% if recurring false alarms occur during normal cutting.
- 3
Confirm MD32010 collision mode setting: 0=disabled, 1=enabled with threshold, 2=enabled with load-dependent detection. If mode=1, switch to mode=2 to allow adaptive collision sensitivity that adjusts with spindle load.
- 4
After parameter adjustment, perform a machine warm-up cycle and re-test axis movement. Monitor servo current oscilloscope trace in [Diagnosis] → [Measuring] menu to confirm load peaks remain below revised threshold.
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