How to Quickly Diagnose a CNC Lathe's Feed Axis Blockage

I. Check Alarm Information and System Status (Complete within 1 minute)

1. First, observe whether the operation panel displays a servo alarm code, such as "ALM 414" for FANUC systems or "108/118" for Siemens systems, directly indicating a driver or encoder malfunction.

2. Confirm that the emergency stop button is released and the "machine lock" function is not enabled. Check the LED indicator status of the Z-axis servo drive: if it is off, the power supply may not be on; if it is flashing, there is usually a communication or feedback problem.

II. Check Basic Enable Conditions and Mechanical Status (Complete within 2 minutes)

1. Power Supply and Voltage: Confirm that the Z-axis servo drive is powered normally. Use a multimeter to measure whether the input voltage is a standard three-phase 220V or 380V.

2. Mechanical Jam Judgment: Manually rotate the Z-axis slide. If it cannot move or the resistance is too high, check whether the guide rail is lacking lubrication, whether the lead screw is blocked by iron filings, or whether the brake is not released.

3. Pneumatic Pressure and Lubrication: Check if the pneumatic system pressure is within the range of 0.6–0.8 MPa, and ensure that the clamping mechanism and tool changer are in the released state.

4. Wiring Connections: Focus on checking whether the servo motor power line and encoder feedback line (such as the CNCPMCJF1 interface) are loose, broken, or oxidized.

III. Modular Isolation and Signal Verification (Complete within 2 minutes)

1. Servo System Detection: Check if the driver has alarms such as "Overcurrent (OC)" or "Overload (OL)," and try resetting and re-enabling it.

2. Control System Verification: Enter the CNC diagnostic interface and check whether feed commands are issued and whether the PLC output point activates the servo enable signal.

3. Parameter Verification: Check whether key parameters such as acceleration and gain (such as FANUC's #1420 and #1422) are missing or mistakenly modified.

4. Replacement test: Temporarily replace the X-axis driver with the Z-axis driver. If the Z-axis resumes movement, the original driver is faulty; otherwise, the problem lies with the motor or control side.