How to quickly troubleshoot a CNC lathe feed axis that is not moving

I. Preliminary Sensory Inspection (Look, Smell, Listen, Touch)

Look: Check if the control panel displays alarm codes (e.g., "ALM 414" on a FANUC system indicates a Z-axis servo alarm);

Smell: Check for any burning electrical odor, indicating a driver or motor malfunction;

Listen: Check for any clicking or buzzing sounds during startup, reflecting the driver's self-test status;

Touch: After stopping the machine, touch the servo motor to check its temperature. Overheating may be due to overload or poor heat dissipation.

II. Step-by-Step Troubleshooting Process

1. Confirm Basic Enable Conditions

Check if the "Emergency Stop" button is released;

Confirm that the "Machine Lock" or "Z-Axis Lock" functions are not mistakenly enabled;

Check if the system is in servo-enabled mode. Some systems require "Emergency Stop Release + Servo Enable" to drive the motor.

2. Check Power Supply and Voltage
Confirm that the Z-axis servo drive power is on;
Use a multimeter to measure whether the input voltage is normal (usually three-phase 220V or 380V);
If the voltage is abnormal, check the air switch, fuse, or power module.

3. Determine if the Mechanism is Jammed
Manually rotate the Z-axis slide to feel for any jamming;
If the resistance is high, check if the guide rail is lacking lubrication, if the lead screw is blocked by metal filings, or if the brake is not released;
Check if the pneumatic/hydraulic system pressure is normal (generally pneumatic pressure 0.6–0.8MPa).

4. Check Electrical Connections
Check if the servo motor power line and encoder feedback line are loose, broken, or have poor contact;
Pay special attention to the reliability of the encoder CNCPMCJF1 interface connection;
If the encoder filament is broken, it will result in no feedback signal, causing the position loop to malfunction.

5. Check Servo System Status
Observe the status of the servo driver's LED indicators; Check the alarm codes (e.g., alarms 108 and 118 in Siemens systems indicate dirty measuring sensors); If the driver reports "overcurrent" or "overload," the motor may be damaged or the parameters may be incorrectly set.

6. Check Control System Signals
Check if feed commands are issued using the CNC diagnostic function; Check if the PLC output points are properly activating the servo enable signal; Verify system parameters (e.g., FANUC's #1420 and #1422 are acceleration settings) to prevent parameter loss or accidental modification.