Every alarm code on a deep hole drilling machine tells you where to look and what to check. This quick reference is organized by system so operators can find the relevant section fast. Keep a printed copy at the machine.
CNC Axis Alarms
Position and Servo Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| PS 300 | Position deviation too large (axis n) | Following error exceeded alarm threshold | Check mechanical binding, servo tuning, coupling |
| PS 306 | Position deviation at standstill | Axis moved while stopped | Check brake (vertical axis), check for external force |
| PS 310 | Excessive error at stop | Overshoot — axis passes commanded position | Check servo gains, deceleration parameters |
| PS 400 | Servo drive fault (axis n) | Drive alarm detected | Check drive status LED, fault code, power supply |
| PS 410 | Servo motor overheat | Motor temperature exceeded limit | Check cooling fan, load condition, ambient temperature |
| PS 420 | Encoder battery alarm | Battery voltage low for absolute encoder | Replace encoder battery — do not turn off machine |
| PS 430 | Encoder disconnection | Feedback signal lost | Check encoder cable, connector at motor and drive |
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| PS 410 | Axis motor overheat (coolant ingress) | Coolant leaking into motor housing | Check motor seal, dry motor, replace if damaged |
| PS 430 | Encoder signal loss (coolant on encoder) | Coolant contamination of encoder | Replace encoder seal, clean or replace encoder |
| Axis overcurrent | Drive overcurrent fault | Binding + coolant-contaminated way covers | Inspect way covers, clean, lubricate |
Spindle Alarms
Spindle Drive Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| SP 901 | Spindle load exceeded | Cutting load above programmed limit | Check drill condition, feed rate, material |
| SP 902 | Spindle speed deviation | Actual speed differs from commanded | Check spindle drive, encoder feedback |
| SP 910 | Spindle drive fault | Drive internal fault | Check drive status, cooling, power supply |
| SP 920 | Spindle overheat | Bearing or motor temperature high | Check cooling, reduce load, check bearings |
| SP 930 | Spindle orientation fault | Orientation position not reached | Check orientation sensor, encoder, brake |
Spindle Coolant Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| SP 940 | Spindle coolant pressure low | Rotary union seal failure, pump fault | Check rotary union, verify pump operation |
| SP 941 | Spindle coolant flow low | Coolant supply restriction | Check filter, supply line, rotary union |
| SP 942 | Coolant temperature high | Chiller or heat exchanger fault | Check chiller, clean heat exchanger |
Coolant System Alarms
Pressure and Flow Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| CL 001 | Coolant pressure low | Pump fault, clogged filter, system leak | Check pump, check filter ΔP, inspect for leaks |
| CL 002 | Coolant pressure high | Blocked coolant passage, closed valve | Check coolant path, verify valve positions |
| CL 003 | Coolant flow low | Pump wear, blocked line, air in system | Check pump condition, purge air, inspect lines |
| CL 004 | Coolant temperature high | Chiller fault, high ambient, low coolant level | Check chiller, check coolant level, clean tank |
| CL 005 | Coolant level low | Evaporation, leak, insufficient fill | Add coolant, check for leaks |
| CL 006 | Coolant filter clogged | Differential pressure across filter high | Replace or clean filter element |
Coolant Quality Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| CL 010 | Coolant concentration out of range | Evaporation, water addition, coolant degradation | Check concentration, adjust with concentrate or water |
| CL 011 | Coolant pH out of range | Bacterial growth, coolant depletion | Test bacteria, add biocide or replace coolant |
| CL 012 | Coolant tramp oil high | Hydraulic leak, way oil leakage | Identify source, skim oil, investigate |
Chip Evacuation Alarms
Chip System Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| CH 001 | Chip conveyor overload | Chip jam, conveyor mechanical binding | Clear chip jam, check conveyor drive, inspect chain |
| CH 002 | Chip basket full | Chip volume exceeds basket capacity | Empty chip basket, check conveyor timing |
| CH 003 | Chip tube blocked | Chip packing in BTA chip tube | Retract drill, clear chip tube with compressed air |
| CH 010 | Chip separator overload | Excessive chip load, separator mechanical issue | Reduce feed rate, check separator drive |
| CH 011 | Coolant return restricted | Chip blockage in return line | Flush return line with compressed air or water |
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| PR 001 | Chip shape abnormal | Chip breaker geometry, coolant pressure | Check chip breaker on drill, verify coolant pressure |
| PR 002 | Chip packing detected | Spindle load + coolant pressure change | Stop feed, retract drill, clear chips |
| PR 003 | Drill torque exceeded | Overload condition | Reduce feed rate, check drill condition |
Safety System Alarms
Interlock and Guard Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| SF 001 | Safety door open | Door not closed or interlock fault | Close door, check interlock switch |
| SF 002 | Light curtain interrupted | Object in protected zone | Clear zone, check light curtain alignment |
| SF 003 | Emergency stop activated | E-stop button pressed | Release E-stop, reset circuit |
| SF 004 | Safety relay fault | Internal safety relay failure | Check safety relay, replace if faulty |
| SF 010 | Coolant hose whip sensor | Coolant hose movement detected | Secure coolant hose, check whip restraint |
System Protection Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| SF 020 | Air pressure low | Compressor off, line leak, regulator fault | Check air supply, verify minimum pressure |
| SF 021 | Hydraulic pressure low | Hydraulic pump fault, leak | Check hydraulic system, pressure setting |
| SF 030 | Lubrication system fault | Lubrication pump failure, low oil level | Check lubricator, refill oil, prime pump |
| SF 031 | Way lubrication interval exceeded | Lubrication cycle not completed | Check lubricator function, verify distribution |
PLC and System Faults
PLC Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| PLC 001 | PLC I/O module fault | Module failure, loose wiring | Check I/O module status, reseat or replace |
| PLC 002 | Remote I/O communication lost | Network cable fault, node failure | Check communication cable, verify node power |
| PLC 003 | PLC program error | Logic error, corrupted program | Note alarm code, contact machine builder |
| PLC 010 | Unconditional alarm (custom) | Machine-specific condition | Check machine builder alarm documentation |
Communication Alarms
| Alarm Code | Description | Likely Cause | Corrective Action |
|---|
| CM 001 | CNC – PLC communication error | Data bus fault, cable damage | Restart system, check communication cables |
| CM 002 | Servo link communication error | Fiber optic cable fault | Check fiber optic cables at servo drive |
| CM 010 | MES / DNC communication lost | Network outage, server down | Check network connection, verify host system |
Alarm Handling Procedure
General Alarm Response
| Step | Action | Detail |
|---|
| 1 | Note alarm code and description | Record exact code from CNC display |
| 2 | Check alarm category | Axis, spindle, coolant, safety, or system |
| 3 | Check machine condition | Is cutting stopped? Is it safe to investigate? |
| 4 | Look up corrective action | Use this reference or machine manual |
| 5 | Perform corrective action | Follow specific steps for the alarm |
| 6 | Reset alarm | Clear alarm from CNC (if cause is resolved) |
| 7 | Return to safe operation | Re-start cutting cycle from appropriate position |
| 8 | Log the alarm | Date, time, code, cause, corrective action |
Alarm Reset After Deep Hole Drilling Interruption
| Condition | Recommended Action | Reason |
|---|
| Alarm while drilling (mid-hole) | Retract drill before resetting | Drill is in the hole — restarting without retracting can cause damage |
| Alarm at hole completion | Normal retract — inspect hole | Confirm hole is not damaged before next cycle |
| Alarm at machine idle | Safe to reset — no cutting in progress | Verify cause is addressed |
| Alarm with drill in workpiece | Manual retract before power cycle | Power cycle with drill in hole may lose position reference |
FAQ
What is the most common alarm on deep hole drilling machines?
Coolant pressure low (CL 001) and position deviation too large (PS 300) are the most common alarms. Low coolant pressure is typically caused by clogged filters, pump wear, or system leaks. Position deviation is typically caused by mechanical binding, chip ingress into way covers, or loose couplings. Both are addressed by systematic inspection — check the simple things first.
How do I clear an alarm on a deep hole drilling machine?
First, identify and correct the root cause of the alarm — never clear an alarm without addressing the condition. Then press the alarm reset button on the CNC panel (typically labeled RESET or ALARM RESET). If the alarm persists, the root cause has not been resolved. Some alarms require a power cycle to clear. Refer to your machine-specific manual for alarm reset procedures.
What should I do if the coolant pressure low alarm activates during drilling?
Stop feed immediately (feed hold). Do not retract the drill yet. Check the coolant pressure gauge — if pressure is zero, the pump may have failed. If pressure is low but not zero, check the filter differential pressure gauge — a clogged filter is the most common cause. If the filter is clean, check coolant level in the tank. Once the cause is identified and addressed, retract the drill and inspect the hole before continuing.
Why does my machine show axis overload alarms repeatedly?
Repeated axis overload alarms indicate a mechanical problem — not an electrical problem. Check: guideway lubrication (dry ways cause high friction), way cover condition (damaged covers allow chip ingress), ball screw condition (wear or damage creates mechanical binding), and gib adjustment (overtightened gibs cause binding). Electrical servo problems rarely cause repeated overload alarms — they cause immediate faults, not gradual overloads.
Where can I find the alarm code list for my specific deep hole drilling machine?
The machine-specific alarm code list is in the maintenance manual provided by the machine builder. Fanuc, Siemens, Heidenhain, and Mitsubishi each publish standard alarm code lists for their CNC controls. This quick reference covers common alarms across most deep hole drilling machines — but always verify alarm codes and corrective actions against your machine-specific documentation.
This quick reference covers common alarm codes found on typical deep hole drilling machines. Always verify alarm codes against your machine-specific manual. Post this reference at the machine and review during shift handover so all operators respond consistently to alarm conditions. This article reflects industry practice as of 2026.
