Siemens alarm 25010: Axis %1 pollution of measuring system
SINUMERIK axis/spindle alarm · Siemens 840D/810D powerline
What it means
The NCK detected degradation of the active measuring system typical of contamination: signal amplitude and mark quality fall below acceptable levels. The alarm warns before total signal loss; the axis is usually stopped depending on the configured alarm reaction.
Likely causes
- chips, oil mist or coolant film on the linear scale or encoder disc
- condensation inside the encoder housing
- weakening LED/light unit or aging encoder electronics
- damaged seals allowing ingress of dirt
- noise injection from broken screening simulating pollution
Triage note: Clean and inspect the measuring system first; recurring alarms usually precede hard encoder faults.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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6FX2001 series encoder
encoder · Common cause
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linear scale sealing wipers per machine builder
encoder · Check if others ruled out
Need the part urgently?
Send us alarm 25010 with your machine details — typical RFQ turnaround is 24–48h.